MGE UPS Systems 3.5 to 21 kVA N+1 Owner`s manual

3.5 to 21 kVA N+1
Inverter
Owner's Manual
I M P O R TA N T S A F E T Y I N S T R U C T I O N S
SAVE THESE INSTRUCTIONS
This manual contains important instructions for all static
inverters, that must be followed during installation, operation, and maintenance of the equipment.
WARNING
Opening enclosures expose hazardous voltages.
personnel only.
Always refer service to qualified
ATTENTION
L'ouverture des cabinets expose des tensions dangereuses. Assurez-vous toujours que
le service ne soit fait que par des personnes qualifiees.
WARNUNG!
Das öffnen der Gehäuse legen gefährliche Spannungen bloss. Service sollte immer nur
von qualifizierten Personal durchgeführt werden.
WARNING
As standards, specifications, and designs are subject to change, please ask for
confirmation of the information given in this publication.
ATTENTION
Comme les normes, spécifications et produits peuvent changer, veuillez demander
confirmation des informations contenues dans cette publication.
WARNUNG!
Normen, Spezifizierungen und Pläne unterliegen Anderungen. Bitte verlangen Sie eine
Bestätigung über alle Informationen, die in dieser Ausgabe gemacht wurden.
NOTE
This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to part 15 of the FCC rules. These limits are designed to provide
reasonable protection against harmful interference when the equipment is operated in a
commercial environment. This equipment generates, uses, and can radiate radio
frequency energy and, if not installed and used in accordance with the instruction
manual, may cause harmful interference to radio communications. Operation of this
equipment in a residential area is likely to cause harmful interference in which case the
user will be required to correct the interference at user's own expense.
WARNING
To reduce the risk of fire or electric shock, install in a temperature and humidity
controlled indoor area free of conductive contaminants.
This equipment is intended only for installations in a RESTRICTED ACCESS LOCATION.
ATTENTION
Pour réduire le riske d'inccendie ou d'électrocution, installer dans une enciente
intérieure contrôlée en température et humidité et sans contaminants conducteurs.
Ce matériel est destiné seulement pour des installations dans un EMPLACEMENT
RESTREINT d'cAccès.
WARNUNG!
Um die Gefahr von Feuer und elektrischem Schock zu reduzieren, muss das Gerät in
einem temperatur - und feuchtigkeitskontrollierten Raum, frei von leitungsfähigen
Verunreinigungen, installiert werden. Dieses Gerät ist nur für die Installation an einem
Ort mit eingeschränkter Zugangserlaubnis vorgesehen.
Diese Ausrüstung ist nur für Anlagen in einem EINGESCHRäNKTEN ZUGRIFF
STANDORT bestimmti.
WARNING
HIGH LEAKAGE CURRENT. Earth connection essential before connecting supply.
ATTENTION
COURANT DE FUITE ELEVE.
raccordement au reseau.
Raccordement a la terre indispensable avant le
WARNUNG!
Hoher Ableitstrom Vor Inbetriebnahme Schutzleiterverbindung herstellen.
3.5 to 21 kVA N+1 Inverter
page ii
Owner’s Manual
This manual covers these models:
Product:
List number:
64034
64074
64104
64144
64174
64214
Comcode reference:
Rating:
407-607-853
3.5 kVA
7.0 kVA
10.5 kVA
14.0 kVA
17.5 kVA
21.0 kVA
3.5 kVA to 21.5 kVA Inverter
Owner's Manual
For service call
1-800-523-0142
86-153460-01 X1 03/02
Copyright © 2002 MGE UPS Systems, Inc.
All rights reserved. Printed in U.S.A.
MGE UPS Systems, Inc.
1660 Scenic Avenue
Costa Mesa, CA 92626
(714) 557-1636
page iii
3.5 to 21 kVA N+1 Inverter
3.5 to 21 kVA N+1 Inverter
Owner ’s Manual
Warranty
The liability of MGE UPS Systems, Inc. hereunder is limited to replacing or repairing at MGE UPS Systems, Inc.’s factory
or on the job site at MGE UPS Systems, Inc.’s option, any part or parts which are defective, including labor, for a period of 12
months from the date of purchase. The MGE UPS Systems, Inc. shall have the sole right to determine if the parts are to be
repaired at the job site or whether they are to be returned to the factory for repair or replacement. All items returned to MGE
UPS Systems, Inc. for repair or replacement must be sent freight prepaid to its factory. Purchaser must obtain MGE UPS
Systems, Inc.’s Return Materials Authorization prior to returning items. The above conditions must be met if warranty is to be
valid. MGE UPS Systems, Inc. will not be liable for any damage done by unauthorized repair work, unauthorized replacement
parts, from any misapplication of the item, or for damage due to accident, abuse, or Act of God.
In no event shall the MGE UPS Systems, Inc. be liable for loss, damage, or expense directly or indirectly arising from the
use of the units, or from any other cause, except as expressly stated in this warranty. MGE UPS Systems, Inc. makes no
warranties, express or implied, including any warranty as to merchantability or fitness for a particular purpose or use. MGE
UPS Systems, Inc. is not liable for and Purchaser waives any right of action it has or may have against MGE UPS Systems,
Inc. for any consequential or special damages arising out of any breach of warranty, and for any damages Purchaser may
claim for damage to any property or injury or death to any person arising out of its purchase of the use, operation or
maintenance of the product. MGE UPS Systems, Inc. will not be liable for any labor subcontracted or performed by Purchaser
for preparation of warranted item for return to MGE UPS Systems, Inc.’s factory or for preparation work for field repair or
replacement. Invoicing of MGE UPS Systems, Inc. for labor either performed or subcontracted by Purchaser will not be
considered as a liability by the MGE UPS Systems, Inc.
This warranty shall be exclusive of any and all other warranties express or implied and may be modified only by a writing
signed by an officer of the MGE UPS Systems, Inc. This warranty shall extend to the Purchaser but to no one else.
Accessories supplied by MGE UPS Systems, Inc., but manufactured by others, carry any warranty the manufacturers have
made to MGE UPS Systems, Inc. and which can be passed on to Purchaser.
MGE UPS Systems, Inc. makes no warranty with respect to whether the products sold hereunder infringe any patent,
U.S. or foreign, and Purchaser represents that any specially ordered products do not infringe any patent. Purchaser agrees to
indemnify and hold MGE UPS Systems, Inc. harmless from any liability by virtue of any patent claims where Purchaser has
ordered a product conforming to Purchaser’s specifications, or conforming to Purchaser’s specific design.
Purchaser has not relied and shall not rely on any oral representation regarding the Product sold hereunder and any oral
representation shall not bind MGE UPS Systems, Inc. and shall not be part of any warranty.
There are no warranties which extend beyond the description on the face hereof. In no event shall MGE UPS Systems,
Inc. be responsible for consequential damages or for any damages except as expressly stated herein.
Service and Factory Repair - Call 1 - 800 - 523 - 0142
Direct questions about the operation, repair, or servicing of this equipment to MGE UPS Systems, Inc. Technical Support
Services. Include the part number and serial number of the unit in any correspondence. Should you require factory service for
your equipment, contact MGE UPS Systems, Inc. Technical Support Services and obtain a Return Materials Authorization
(RMA) prior to shipping your unit. Never ship equipment to MGE UPS Systems, Inc. without first obtaining an RMA.
Proprietary Rights Statement
The information in this manual is the property of MGE UPS Systems, Inc., and represents a proprietary article in which
MGE UPS Systems, Inc., retains any and all patent rights, including exclusive rights of use and/or manufacture and/or sale.
Possession of this information does not convey any permission to reproduce, print, or manufacture the article or articles
shown herein. Such permission may be granted only by specific written authorization, signed by an officer of MGE UPS
Systems, Inc.
IBM, PC-AT, ES/9000, and AS/400 are trademarks of International Business Machines Corporation. MGE and MGE UPS
Systems are trademarks of MGE UPS Systems, Inc. Other trademarks that may be used herein are owned by their respective
companies and are referred to in an editorial fashion only.
Revision History
3.5 to 21 kVA N+1 Inverter Owner’s Manual
86-153460-01
Copyright © 2002 MGE UPS Systems, Inc.
Revision: X0
Revision: X1
RND-000999
page iv
All rights reserved
12/2001
03/2002
Printed in U.S.A.
Owner’s Manual
Contents
section
description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page
Important Safety Instructions . . . . . . . . . . . . . .Inside Front Cover
Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Service & Factory Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Property Rights Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v
How to Use This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ix
Chapter I -
Introduction
1.0
1.1
1.2
1.3
1.3.1
1.3.2
1.3.3
1.3.4
1.3.5
1.3.6
1.3.7
1.3.8
1.3.9
1.3.10
1.3.11
1.3.12
1.4
1.5
1.6
1.7
1.7.1
1.7.2
1.7.3
1.7.4
1.7.5
1.7.6
1.7.7
1.7.8
1.7.9
1.7.10
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Standard Product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
DC Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
AC Output (per module) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
Power Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Total Harmonic Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Line Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Load Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Output Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Short Circuit Current (SCC) . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Overload Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Transient Deviation and Recovery . . . . . . . . . . . . . . . . . . . . . .1-4
EMI Emission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Indicators and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Remote Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
Mechanical Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Environmental Specification . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Shipping Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Operating Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Operating Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Audible Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Thermal Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Safety Approvals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Contents
page v
3.5 to 21 kVA N+1 Inverter
section
description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page
Chapter II - Installation & Operation
2.0
2.1
2.1.1
2.1.2
2.2
2.2.0
2.2.1
2.3
2.3.0
2.3.1
2.3.1.1
2.3.1.2
2.3.1.3
2.3.2
2.3.3
2.3.3.1
2.3.3.2
2.3.3.3
2.3.4
2.3.5
2.3.5.1
2.3.5.2
2.3.6
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Receiving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Prerequisites to Installation . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Mechanical Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
Common Installation Procedure . . . . . . . . . . . . . . . . . . . . . . .2-5
Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
Input and Output Cable Connections . . . . . . . . . . . . . . . . . . . .2-5
AC Input Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
DC Input Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6
AC Input/Output Voltage Selection . . . . . . . . . . . . . . . . . . . . .2-7
Software Configuration Set-Up . . . . . . . . . . . . . . . . . . . . . . . .2-7
Dual Processor Set-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7
System Personalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8
Redundant Controller Set-Up . . . . . . . . . . . . . . . . . . . . . . . . .2-8
Power Module Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8
Start-Up Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8
Power-Up Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9
Powering Up the Inverters . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9
De-Energizing the System . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9
Chapter III - Maintenance
3.0
3.1
3.2
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.3
3.4
3.4.1
3.4.2
3.4.2.1
3.4.2.2
3.4.2.3
3.4.2.4
3.4.2.5
3.4.2.6
3.4.2.7
3.4.2.8
3.4.2.9
3.4.2.10
page vi
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Safety Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Preventative Maintenance Procedures . . . . . . . . . . . . . . . . . .3-1
Dust Removal and Exterior Cleaning . . . . . . . . . . . . . . . . . . . .3-1
Air Intake Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2
AC Fan Replacement Procedure . . . . . . . . . . . . . . . . . . . . . . .3-2
DC Fan Replacement Procedure . . . . . . . . . . . . . . . . . . . . . .3-2
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
Troubleshooting and Servicing . . . . . . . . . . . . . . . . . . . . . . . .3-3
Installation Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
Inverter System Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
DC Input Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
AC Output Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Cable Connection and Static Switch Module . . . . . . . . . . . . . .3-4
ON-LINE Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
OFF-LINE Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Inverter Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Battery Booster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Dual Half-Bridge Inverter . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5
Average Current Mode Control . . . . . . . . . . . . . . . . . . . . . . . .3-5
Contents
Owner’s Manual
section
description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page
Chapter IV - Theory of Operation
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.7.1
4.7.1.1
4.7.1.2
4.8
4.8.1
4.8.1.1
4.8.1.2
4.8.1.3
4.8.1.4
4.8.1.5
4.8.1.6
4.8.1.7
4.8.1.8
4.8.1.9
4.8.1.10
4.8.1.11
4.8.2
4.8.2.1
4.8.3
4.8.3.1
4.8.3.2
Glossary
Scope
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
“Receiver” Cabinet “Controller” . . . . . . . . . . . . . . . . . . . . . . . .4-1
LCD “Display” Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
Alarm Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
Installation “Set-Up” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
DC Input Power Connections . . . . . . . . . . . . . . . . . . . . . . . . .4-4
Inverter AC Output Distribution . . . . . . . . . . . . . . . . . . . . . . . .4-4
Power Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
Power Module Configuration . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
Battery Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
4.7.1.1.1 Battery Booster Operstion . . . . . . . . . . . . . . . . . . . .4-7
Inverter
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.7.1.2.1 Dual Inverters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.7.1.2.2 Inverter Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.7.1.2.3 Inverter Control . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
4.7.1.2.4 Average Current Mode . . . . . . . . . . . . . . . . . . . . . . .4-9
4.7.1.2.5 Inverter Sweep Generator . . . . . . . . . . . . . . . . . . . .4-9
4.7.1.2.6 Fault Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-9
4.7.1.2.7 Internal Power Supply . . . . . . . . . . . . . . . . . . . . . .4-10
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10
“Controller” Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10
“Controller” Input Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11
DC Current Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11
Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11
Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12
Alarm Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12
“Watch Dog” Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-12
High Voltage Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13
Under Voltage Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13
Sine Wave Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13
“Display” Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13
“Controller” Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13
Static Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13
Static Switch Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-14
Current Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-14
Output Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-14
Back-Feed Current Sensor . . . . . . . . . . . . . . . . . . . . . . . . . .4-14
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .g-1
Figure
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page
1-1
2-1
2-2
2-3
System Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2
Installation Drawing, 7 kVA Inverter System . . . . . . . . . . . . . .2-3
Front View, 7 kVA, System Component Description . . . . . . . . .2-4
Static Switch Jumper Positions . . . . . . . . . . . . . . . . . . . . . . . .2-6
Contents
page vii
3.5 to 21 kVA N+1 Inverter
page viii
Figure
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page
3-2
4-1
Dual Inverter and Waveform Diagram . . . . . . . . . . . . . . . . . . .3-5
Block Diagram of the 21 kVA Inverter System . . . . . . . . . . . . .4-2
4-2
4-3
4-4
Block Diagram of the S4 Inverter Power System . . . . . . . . . . .4-3
Block Diagram of Power Module . . . . . . . . . . . . . . . . . . . . . . .4-5
Voltage and Current Waveforms of DC/DC Battery Booster . . .4-6
Table
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page
1-1
1-2
1-3
1-4
1-5
3-1
3-2
Inverter System Characteristics . . . . . . . . . . . . . . . . . . . . . . . .1-2
Inverter Module Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
S4 AC Output Current Ratings . . . . . . . . . . . . . . . . . . . . . . . .1-3
Alarm Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
S4 Receiver Cabinet Mechanical Dimensions and Weights . . .1-6
Installation Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4
Contents
Owner’s Manual
How To Use This Manual: This manual is designed for ease of use and easy location of information.
To quickly find the meaning of terms used within the text, look in the Glossary.
To quickly find a specific topic, look in the Index.
This manual uses Noteboxes to convey important information. Noteboxes come in four varieties:
WARNING
A WARNING
notebox
indicates
i n fo r m a t i o n
provided to protect the
user
and
service
personnel against safety
hazards and/or possible
equipment damage
IMPORTANT
An IMPORTANT notebox
indicates
i n fo r m a t i o n
provided as an operating
instruction, or as an
operating tip.
CAUTION
A C AU T I O N n o t e b o x
indicates infor mation
provided to protect the
user
and
service
personnel
against
possible
equipment
damage.
NOTE
A
N OT E
notebox
indicates infor mation
provided
as
an
operating tip or an
e q u i p m e n t fe a t u r e .
page ix
3.5 to 21 kVA N+1 Inverter
(This page left blank intentionally.)
page x
Owner’s Manual
Introduction
WARNING
An AC output will be present at the output terminals
immediately when AC input is energized.
ATTENTION
La tension alternative de sortie appara ît dès la mise sous
tension de l'entrée.
WARNUNG
Eine Ausgangsspannung liegt an den Ausgangsklemmen,
sobald der Netzeingang angeschlossen wird.
1.0
Scope
This manual provides technical information for installation, operation, and maintenance of MGE UPS Systems’
modular inverter systems series ranging from 3.5 kVA to 21 kVA. Please read this manual thoroughly before
installing and operating the system. Please retain this manual for future reference.
The manual is divided into four sections:
Section I — Introduction
This section introduces the S4 3.5 to 21 kVA static inverters, including a general description of the
inverter and its components, and inverter specifications.
Section II — Installation & Operation
This chapter describes installation of the inverters, including receiving, handling, and storage procedures; prerequisites to the installation; installation procedures; and start-up procedures.
Section III — Maintenance
This section describes maintenance of the inverters, including preventive maintenance routines, and
recommended spare parts.
Section IV — Theory of Operation
An appendix provides a glossary of technical terms at the end of this manual provides definitions of
terms used within the text. An index makes it easy to quickly locate topics of interest.
1.1
General Description
This static, modular inverter system series provide stable, distortion-free AC power from a DC input source at a
selectable output voltage and frequency prior to shipment, for sensitive equipment which must be operated in
Introduction
page 1 — 1
3.5 to 21 kVA N+1 Inverter
locations where commercial AC power is not available. With a built-in static transfer switch, the inverter also forms
a reliable and economical part of uninterruptible power supply systems in either on-line or off-line mode. See
chapter 8, Theory of Operation, for detailed information on inverter characteristics. This series employed modular
design to provide N+1 redundancy, and twin controller cards to double reliability. There are three distinctive parts
in these tower inverter systems. The top part is a built-in module that houses the twin controller, alarm cards, LCD
unit, and LED indicators. The center part is a built-in module that houses a static transfer switch, and where input
and output connectors are located. It is easily recognized by twin fan front panel. Above and below this static switch
module are individual inverter modules rated 3.5 kVA/3kW each (those with single fan front panel).
Topaz S4 systems are available in six receiver cabinet configurations housing 1 to 6 inverters, a static transfer
switch console and redundant microcontroller modules.
Figure 1-1: System Configurations
3.5 kVA
7 kVA/3.5 kVA
N+1
10.5 kVA/7 kVA
N+1
14 kVA/10.5 kVA
N+1
17.5 kVA/14 kVA
N+1
21 kVA/17.5 kVA
N+1
1.2 Standard Products
Consult table 1 below for the system(s) you are working on.
Table 1-1: Inverter System Characteristics
Part
Number
Power
rating
(kVA)
Nominal
Input
Voltage
(VDC)
Input
Voltage
Range
(VDC)
Maximum
Input Current
@ -40VDC
(Amperes)
64034
3.5
(-48)
(-40 to -60)
88
29
16
15
64074
7
(-48)
(-40 to -60)
176
58
32
30
29
51 or 60
64104
10.5
(-48)
(-40 to -60)
265
87
48
45
43.5
52 or 60
64144
14
(-48)
(-40 to -60)
353
116
64
60
58
53 or 60
64174
17.5
(-48)
(-40 to -60)
441
145
80
75
72.5
54 or 60
64214
21
(-48)
(-40 to -60)
529
174
96
90
87
55 or 60
page 1 — 2
Introduction
Nominal Output
Amperes at selectable
output voltage of:
120
220
230
240
14.5
Selectable
Output
Frequency
Hz
50 or 60
Owner’s Manual
Table 1-2: Inverter Module Dimensions
Inverter Module
HEIGHT (in/cm)
DEPTH (in/cm)
WIDTH (in/cm)
WEIGHT (lb/kg)
5.18 / 13.3
15.12 / 38.85
15.76 / 40.5
46 / 20.44
64004-9MSK1
Note: Weight: 1 six-mod receiver = 135 lbs. 1 UPS Module = 46 lbs.
Total System Weight, 21 kVA system = 411 lbs.
1.3
Electrical Specifications
Electrical Specifications are subject to revision without notice.
1.3.1
DC Input
Nominal: -48Vdc; Operating Range: -39.5Vdc to -60 Vdc
NOTE
An external DC circuit breaker or fuse should be used at the DC source.
1.3.2
AC Output (per module)
Voltage:
Current:
Frequency:
120Vrms
25Arms
50Hz
or
or
or
240Vrms
12.5Arms
60Hz
Table 1-3: S4 AC Output Current Ratings
UNIT
3.5 kVA
AC AMPERES)
7 kVA
(AC AMPERES)
10.5 kVA
4 kVA
(AC AMPERES) (AC AMPERES)
17.5 kVA
(AC AMPERES)
21 kVA
(AC AMPERES)
VAC
100*
27.3
54.5
81.8
109.1
136.4
163.6
110
27.3
54.5
81.8
109.1
136.4
163.6
115
26.1
52.2
78.3
104.3
130.4
156.5
120
25.0
50.0
75.0
100.0
125.0
150.0
200
15.0
30.0
45.0
60.0
75.0
90.0
220
13.6
27.3
40.9
54.5
68.2
81.8
230
13.0
26.1
39.1
52.2
65.2
78.3
240
12.5
25.0
37.5
50.0
62.5
75.0
* 100VAC version needs to be derated.
1.3.3
Efficiency
85% minimum, 88% typical (on-line mode); 97% typical (off-line mode) at full kVA/Watt load.
Introduction
page 1 — 3
3.5 to 21 kVA N+1 Inverter
1.3.4
Power Factor
Rated kVA is available over a power factor range of 0.6 lagging to 0.6 leading at nominal voltage. Watt rating should
not be exceeded.
1.3.5
Total Harmonic Distortion
Less than 1% for linear load conditions, 3% maximum for crest factor loads up to 3:1.
1.3.6
Line Regulation
System output voltage variation, less than 1% over the DC voltage range.
1.3.7
Load Regulation
System output voltage variation, less than 1% from zero to full load at nominal DC input.
1.3.8
Output Frequency
User-selectable, 50Hz or 60Hz. Free run frequency stability shall be within +/-0.02% of the selected frequency.
1.3.9
Short Circuit Current (SCC)
300% minimum of rated load current for four cycles. A SCC is defined as a current that exceeds 150% of rated
current.
1.3.10 Overload Capability
Continuous overload up to 108% of rated VA/watts at 40°C maximum.
1.3.11 Transient Deviation and Recovery
Within 20% of average value for any change in output current or step change in input voltage within specified limits.
Recovery within 1millisecond from zero to full load
1.3.12 EMI Emission
Less than 30dBrnc.
1.4
Indicators and Controls
See Figure 2-2 on page 2—4 for the location of indicators and control switches.
There are six LED indicators divided into three groups – DS1 and DS2, DS3 and DS4, DS5 and DS6 - on the
“Display” front panel. DS1 and DS2 are indicators of controller A; DS3 and DS4 are indicators for controller B; DS5
and DS6 are for output capacitors’ fuse indicators. Failure of output capacitors will trip output fuses, and will activate
DS5 and/or DS6 indicators
At power-up, one of the two controller units will be up quicker than the other and will take control the system.
Consequently either DS1 (if controller A is in charge) or DS3 (if controller B is in charge) will be on blinking green,
signaling that the system output is ready to be turned on.
The inverter output voltage is turned ON and/or to Stand-by via switch SW1 located on the left side of the LCD
“Display” Panel. Pushing it up is to turn the inverter ON, and pushing it down is to turn the inverter OFF. WARNING:
In the “Stand-by” position, if AC power is applied to the AC input terminal block, AC power will be on the output of
the unit. When the output voltage is on, DS2 (or DS3) indicator will be on green steadily, signaling that every thing
is normal.
page 1 — 4
Introduction
Owner’s Manual
The system measurement information is displayed on the LCD “Display” panel. Switch SW3 is pushed down (or up)
to scroll the LCD’s screens for more information. Individual inverter module has only one control, an ON/OFF circuit
breaker, located at the upper left corner of the front panel. This breaker is used to energize (or de-energize) the
inverter module.
Note: The module circuit breakers must be turned on prior to turning the system output voltage on.
LCD Readout
The LCD unit displays two lines (out of a total of seven lines) of information at a time. Each line can be scrolled
up (or down) independently by toggling switch SW3. Typical seven lines of information are shown below:
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
1.5
INV:
BYP:
LOAD:
AC IN:
DC IN:
LOAD:
INV:
off
static
120V
120V
48.0V
03000 W
1 of 6
normal
normal
100%
60 Hz
073.5A
025.0A
60 Hz
Inverter off/on
Static bypass on/normal operation
Load % on nominal
AC input voltage/frequency
DC voltage/DC current
Load Power (W)/Current (A)
Inverter(s) in operation/frequency
Remote Alarm
The system provides three alarm signals, namely, Utility alarm, Minor alarm, and Major alarm.
5.1 Utility alarm – Utility alarm is ON when utility input voltage is lost/out of tolerance.
5.2 Minor alarm – The system sends out this signal to indicate something is not functioning properly, but inverter
can still maintain the load.
5.3 Major alarm – Whenever load is lost power and the system is energized.
For alarm connection, see Table 1-4.
Alarm Relays
There are three alarm relays. All relays are “form C” type, that is, the relay has a normally open and a normally
closed contact set.
The “Major Alarm” relay will be energized when the system is operating properly, that is, power is being supplied to
the load either from the Inverter or from the Utility. There are two sets of “form C” contact sets on the “Major Alarm”
relay.
The “Minor Alarm” relay will be de-energized, and will be energized for the “alarm” condition. A “Minor” alarm will
be issued if the system is not operating properly. Such an alarm will be issued during over load, battery voltage not
within specified limits, power modules over temperature and module fault.
The “Utility Alarm” relay will be de-energized during normal operation and will be energized for the “alarm” condition.
This alarm will be issued if the utility voltage is not within specified limits or the input frequency is not within proper
limits.
The table below shows the “alarm” and the “non-alarm” terminal block connections. This terminal block is located
in the top, left side of the receiver cabinet. The small front panel must be removed to gain access to the terminal
block.
Introduction
page 1 — 5
3.5 to 21 kVA N+1 Inverter
Table 1-4: Alarm Connections
J21 terminal block screw position
MAJOR ALARM
MAJOR ALARM
No Major Alarm
No Major Alarm
Minor Alarm
No Minor Alarm
Utility Alarm
No Utility Alarm
-------------------
1
2
X
X
X
3
X
4
X
5
6
X
X
7
8
9
X
X
X
X
10
11
12
X
X
X
X
X
“X” indicates a short circuit between J21 terminal block points.
1.6
Mechanical Specification
Table 1-5: S4 Receiver Cabinet Mechanical Dimensions and Weights
MODEL
3.5 kVA
7 kVA
10.5 kVA
14 kVA
17.5 kVA
21 kVA
HEIGHT (in/cm)
15.75 / 40.5
21 / 54
26.25 / 67.5
31.5 / 81
36.75 / 94.5
42 / 107.9
DEPTH (in/cm)
18.5 / 47.5
18.5 / 47.5
18.5 / 47.5
18.5 / 47.5
18.5 / 47.5
18.5 / 47.5
WIDTH (in/cm)
17 / 43.7
17 / 43.7
17 / 43.7
17 / 43.7
17 / 43.7
17 / 43.7
RECEIVER WEIGHT (lb/kg)
67 / 30.4
88 / 39.9
100 / 45.4
111 / 50.3
122 / 55.3
136 / 61.7
RECEIVER + MODULES
WEIGHT (lb/kg)
114 / 51.7
182 / 82.6
241 / 109.3
299 / 135.6
357 / 161.9
418 / 189.6
RECEIVER SHIPPING
WEIGHT (lb/kg)
78 / 35.8
100 / 45.4
112 / 51.6
123 / 55.8
134 / 60.8
148 / 67.1
1.7
Environmental Specifications
1.7.1
Operating Temperature
All models operate to specifications from 0 to +50° C (+32° F. to +122° F).
1.7.2
Shipping Temperature
-40° C to +75° C (-40° F. to +192° F.) for shipping;
Not recommended for storage.
1.7.3
Storage Temperature
-40°C to +60°C (-40°F to +166°F)
1.7.4
Operating Humidity
0 to 90% relative, without condensation.
1.7.5
Operating Altitude
200 feet below to 10,000 feet above sea level
page 1 — 6
Introduction
Owner’s Manual
1.7.6
Audible Noise
Less than 65 dBA per Type 2, IEC and ANSI SI.4, when measured in a 40 dBA environment at a distance of 4 feet
from any surface. At nominal ambient (+23C) and 75% load, typical audible noise is 50 dBA in the ON-LINE mode,
56 dBA in the OFF-LINE mode.
1.7.7
Cooling
Forced air. Air intake is through the front of the unit, exhaust out the sides.
1.7.8
Thermal Dissipation
Heat rejection: 602.28 BTU/Hr for each rated KW of the inverter system. This is based on an inverter efficiency of
85% at full load and does not include load dissipation.
1.7.9
kVA rating
3.5
7
10.5
14
17.5
21
Watts
529
1059
1582
2118
2647
3177
BTU/Hr
1807
3614
5421
7227
9034
10841
Est. A/C, TONS
0.151
0.301
0.452
0.602
0.753
0.903
Safety Approvals
Meets UL/CSA 60950 (listed) and European Standard EN60950.
1.7.10 Reliability
Calculated MTBF at 25° C ambient temperature
Introduction
page 1 — 7
3.5 to 21 kVA N+1 Inverter
(This page left blank intentionally.)
page 1 — 8
Introduction
Owner’s Manual
Installation & Operation
2.0
Scope
This chapter describes installation of the inverters, including receiving, handling, and storage procedures; prerequisites to the installation; installation procedures; and start-up procedures.
2.1
Receiving
Before accepting the shipment from the freight carrier, inspect the exterior surfaces of all shipping containers or
packaging used, and the equipment, for damage that may have occurred during transit. If the shipping containers
or equipment shows evidence of damage, note the damage on the receiving document (bill of lading) prior to signing
for receipt of equipment.
ALL CLAIMS FOR SHIPPING DAMAGE MUST BE FILED DIRECTLY WITH THE CARRIER. Replacements for
damaged components should be ordered through MGE UPS Systems.
2.1.1
Handling
The equipment can be lifted from the top, using the eye-bolts; however, a spreader bar must be used to avoid bending
the bolts or the side panels. The equipment may also be handled using a forklift or pallet mover.
2.1.2
Storage
If the equipment is to be stored prior to installation, it should be stored in a cool, dry, well-ventilated location that is
protected from rain, splashing water, chemical agents, etc. The equipment should be covered with a tarpaulin or
plastic wrapper to protect it against dust, dirt, paint, or other foreign materials.
2.2
Prerequisites to Installation
An efficient installation depends on careful planning and site preparation. Installation of the equipment must be
handled by skilled technicians and electricians familiar with the special requirements of high-voltage electrical
equipment. The installation must comply with the requirements of the National Electrical Code (ANSI/NFPA 70,
latest issue) and local codes as applicable.
We strongly recommend contracting MGE UPS Systems for system start-up. Do not allow unqualified personnel to
handle, install, or operate MGE UPS Systems static inverter systems.
NOTE
The inverter can be mounted close to a rear wall, because there is no rear
access to the unit. All input DC, output AC, and input AC wiring to the inverter
enters through the top or left side of the rack assembly. Service to the inverter
rack is through the front. If a maintenance bypass unit is installed, rear access
is required for this unit.
Installation & Operation
page 2 — 1
3.5 to 21 kVA N+1 Inverter
2.2.0
Mechanical Mounting
The equipment can be either mounted on a floor, or rack-mounted in a 19”, 23”, or 25” rack. Optional
mounting bracket kits can be ordered for rack mounting in a 19” or 23” rack. Ordering information is as
follows:
All receivers and inverter power modules are shipped separately from the factory. Receivers will be shipped
on a pallet. These receivers can be secured to a floor or to some other permanent base using one-half inch
bolts through the four holes in the base supports. The inverter modules will be shipped based on customer’s
discretion on power configuration or the size of the receiver they are using. Modules will be shipped separately
from exterior chassis. Refer to Figure 2-2 on page 2—4.
page 2 —2
Installation & Operation
Owner’s Manual
Figure 2-1: Installation Drawing, 7 kVA Inverter System
FOR 1", 1-1/2"
CONDUITS (4 PLACES)
8.870
6.270
2.825
16.060
FOR 1", 2", 3"
CONDUITS (2 PLACES)
TOP VIEW
12.210
1.650
3.250
FOR 1/2", 3/4"
CONDUITS (2 PLACES)
xxxxx
xxxxx
8.925
11.675
15.775
LEFT SIDE VIEW
Installation & Operation
page 2 — 3
3.5 to 21 kVA N+1 Inverter
Figure 2-2: Front View, 7 kVA, System Component Description
Microcontroller
Power Switch
WARNING:
Communications
Port
WARNING:
Disconnect AC (Mains) and DC supply before removing this cover.
Disconnect AC (Mains) and DC supply before removing this cover.
CONTROLLER
Redundant
Microcontroller
Panel
B
STATUS
INVERTER
BYPASS
AC RACEWAY
FUSE
Primary
Microcontroller
INVERTER
GREEN = NORMAL
YELLOW = WARNING
RED = FAULT/OPEN
STEADY = PRIMARY SOURCE
FLASHING = ALTERNATE SOURCE
ON
S4 INVERTER
CONTROLLER
A
STATUS
BYPASS
COM1
Controller
Status LEDs
!
OFF
SCROLL
LED Scroll
Button
LCD Panel
DC INPUT
!
WARNING!
Cooling Fan
Assembly
OPEN BREAKER BEFORE
REMOVING MODULE
POWER MODULE
3.5 kVA Inverter
Module
GREEN = NORMAL
YELLOW = WARNING
RED = FAULT
STATUS Micro controllerTEMPERATURE
Inverter Module
Status LEDs
S4
WARNING:
Disconnect AC (Mains) and
DC supply before removing this cover.
Static Transfer
Switch Cabinet
DC INPUT
Inverter DC
Input Switch
Thumb Screw
!
WARNING!
OPEN BREAKER BEFORE
REMOVING MODULE
3.5 kVA Inverter
Module
POWER MODULE
GREEN = NORMAL
YELLOW = WARNING
RED = FAULT
STATUS
TEMPERATURE
S4
Receiver Cabinet
Chasis
NOTE: Modules are shipped separately to reveiver cabinet.
page 2 — 4
Installation & Operation
Owner’s Manual
2.2.1
Location
The equipment is designed for installation in a protected environment. Factors to be considered in selecting a
location include ventilation, temperature, humidity, and accessibility. Install the unit in a clean, dry location with an
unrestricted air flow. The equipment is cooled by forced air. Allow at least 6 inches of air space around the
equipment for proper cooling.
2.3
Common Installation Procedure
Note: The installation procedure is common with all units.
2.3.0
Grounding
For safety and proper operation of the unit, including maximum attenuation of electrical noise, suitable grounding is
required. A separate grounding electrode conductor should be connected from the ground (GND) terminal to a
nearby grounding electrode, and should be sized per National Electrical Code Article 250-94. The grounding
electrode should be grounded structural metal, a metal water pipe, or a suitable ground rod (National Electrical Code
250-26). The grounding electrode should be as near as possible to the unit. The S4 will accommodate two 1/0
gauge wire. Customer provides grounding system.
Move the “receiver” cabinet to its intended location, using one of the suggested handling methods. After it is in its
final position, remove the blank panels from the front of the “receiver” cabinet. Blank panels are supplied with the
unit so as to prevent damage to the unit during shipment. Remove these blank panels, but do not discard them.
Remove top cover panel on the receiver’s “static switch” (cover of the panel with two fans) for access to the wiring
area. The connections to be made are the DC input connections, load connections, AC input connections, and
optional remote alarm connections. The connection terminals and buss bars are located at the static switch area,
which is in the center of the receiver cabinet. For safety, the DC safety ground connection should me connected
first, then DC positive (+) connection made next, then the DC negative (-) last.
2.3.1
Input and Output Cable Connections
2.3.1.1 AC Input Circuit Breaker
WARNING
If utility line voltage is connected to the system, an appropriately rated AC
circuit breaker MUST be installed between the supplying AC source and the
inverter plant. Installation must comply with local/national electrical
installation requirements.
Suggested circuit breaker ratings:
Inverter rating
3.5 kVA
7 kVA
10.5 kVA
14 kVA
17.5 kVA
21 kVA
AC breaker rating
30A
60A
100A
125A
150A
200A
2.3.1.2 DC Input Circuit Breaker
Due to tremendous amounts of short circuit current available (in excess of 1000Amps for as long as several
minutes!) from bank(s) of batteries, that supply electrical power to inverter systems, it is extremely important to
connect a properly sized DC circuit breaker at the DC input cable that feeds the inverter system. The following table
is provided as a guide for selecting the proper circuit breaker.
Installation & Operation
page 2 — 5
3.5 to 21 kVA N+1 Inverter
Figure 2-3: Static Switch Jumper Positions
Suggested DC circuit breaker ratings:
Inverter rating
3.5 kVA
7 kVA
10.5 kVA
14 kVA
17.5 kVA
21 kVA
DC breaker rating
125A
250A
375A
500A
650A
750A
2.3.1.3 Connections
All DC input connections are made through the “knock-outs”, located in the top or left side panel. Refer to Figure
2-1. Make sure that the upstream source DC circuit breaker and AC circuit breaker (if applicable) supplying the
inverter are in the off (or open) position. DC input power cables should be sized such that the maximum voltage
drop between inverter bus bar terminals and battery terminals is less than 1.0 volt at the breaker current rating. See
paragraph 2.3.1.2 for breaker rating verses kVA rating. The inverter can accommodate three positive wires and
three negative wires. Two hole lugs, compression dipc with hole spacing of 1: should be used. All ground connections should be made first, then positive (+) DC input cable should be connected, then the negative (-) connection
last. The DC input landings are marked (+) and (–). Insert the input DC power cable through the selected top or
side panel “knock-out”. Connect the positive (+) cable to the upper terminal connection and the negative (–) cable
page 2 —6
Installation & Operation
Owner’s Manual
to the lower terminal connection landing. Note that there is room for three lugs with two holes spaced one inch
apart. Cables and terminal lugs are not furnished with the inverter and must be ordered separately for the 3.5 kVA
to 145 kVA units. The 17.5 kVA and 21 kVA inverter require the super flexible (fine strand) wire, which is supplied
as an option with the Maintenance Bypass unit.
The utility input and output cables are connected to a screw type terminal block. Connect the ground wires first,
then the white neutral wires, then connect the black AC input wire (if applicable) and the black AC output wire. A
separate, optional “Maintenance Bypass” unit and a “Power Distribution” panel (200A Square D “QO” type of circuit
breakers) is available.
2.3.2
AC Input/Output Voltage Selection
The inverter is preset at the factory for 120VAC input, ON-LINE, 120 VAC, 60 Hz output.
If the input voltage or for your installation is different (200VAC to 240VAC), the following procedure MUST be
followed. In the “Static Sw” area, there is a printed circuit board mounted to the right side panel. A multi-pin
connector is located on the printed circuit board, close to the “Static Switch” front panel, identified as J23. This
connector has 13 pins. Its mating plug has 12 positions, with interconnecting wires. This allows the jumper plug
(P13) to be installed in one of two positions. When this jumper plug is in it most forward position (closest to the front
panel), the unit is set for 100-120VAC operation. Removing the plug and installing it in its rear most position selects
200-240VAC operation. Verify that this plug is in the proper position before applying any voltage to the inverter
system. See Figure 2-2.
EMI filer wiring. There are two separate inverter AC output EMI filters. Each filter provides one half of the output
power to the system. These filters must be connected in parallel for 100-120VAC output or connected in series for
200-240VAC output. There are only two wires connected to these two filters. The “Neutral” wire, with the white
band, is connected to the lower EMI filter left-hand stud. The “AC output” wire is connected to the upper EMI filter
right-hand stud. In the 100-120VAC configuration, the left-hand studs of the EMI filters are connected together by
a copper bus bar strap and the two right-hand studs of the EMI filters are connected together by a bus bar strap.
To change to the 200-240VAC connection, remove the wires and bus bars from the output terminals of the EMI filter.
Install the copper bus bar between the lower EMI filter right-hand stud to the upper EMI filter left-hand stud. Reconnect the white “Neutral” wire to the lower EMI filter left-hand stud and the “AC output” wire to the upper EMI filter
right-hand stud. Replace the hardware (flat washer, lock washer, and nut) and tighten the 10MM nuts to the
prescribed torque, 35.4 inch-lbs (4 Nm). Refer to the decal on the cover plate of the static switch for strap positions.
Again, verify that P23 plug on the “Static Switch” printed circuit board (located on the right side panel, is in the
240VAC, rear most position before applying any voltage to the inverter system. The extra copper bus bar may be
discarded. Replace the top cover of the “Static Switch” and secure it with the three previously removed 6-32x1/4”
“Phillips” head screws.
2.3.3
Software Configuration Set-Up
A “Lap-Top” Personal Computer (PC) with the “Field Service Set-up” software for the S4 inverter family needs to be
available and connected to the DB-9 connector of the “Display” panel via the appropriate cable. In systems that do
not have the redundant controller printed circuit board, there is no need to open the “Display” panel or remove the
redundant controller. Go directly to step 3.3.2.
2.3.3.1 Dual Processor Set-Up
The following procedure should be followed for systems that contain a redundant (second) microprocessor. Using
a #2 “Phillips” screw driver, remove the two screws securing the “Display” panel to the “Receiver” rack. Swing the
panel forward, but do not detach it from the rack. Using the “Phillips” screw driver, remove the two screws holding
the microprocessor boards in place. The circuit board securing bracket is also a circuit board extractor. Using this
bracket, pull the top microprocessor circuit board out slightly so that it is disengaged from its 70 pin edge plated
Installation & Operation
page 2 — 7
3.5 to 21 kVA N+1 Inverter
connector. Swing the “Display” panel back to its vertical position and install the two screws to hold the panel in
position. Do not tighten the screws very much, since they will be removed again.
2.3.3.2 System Personalization
Before installing the power modules into the receiver rack, apply the 48 DC input voltage (44 to 56VDC). The
controller (microprocessors) within the unit should become activated. The “Status” indicators on the “Display” panel
should sequence through their self test mode, changing from “red” to “yellow” to “green”, then momentarily off in
approximately 4 seconds. After this, ignore all the LED displays. Using the “Lap-Top” PC, call up the “Filed Service
Set-up” program. In the “Windows” menu, select the desired AC output voltage, frequency, and modes of
operation*. The “Windows” menu will appear similar to the following:
TYPICAL “WINDOWS SET-UP MENU
AC output voltage
100
110
115
120
AC output voltage
200
220
230
240
Output frequency
50 HZ
60 HZ
Restart
AUTOMATIC
MANUAL RESTART
AC bypass available
YES
NO
After the selections are complete, click on the “GO” box. The data will be sent to the appropriate address in the
controllers “EEROM”. Data will be fed back as text to the screen so as to verify that the “EEROM” was set up
properly. Verify that data sent is correct, or repeat this step until the correct data is obtained. Remove the applied
48VDC to the system by turning off the main DC feed circuit breaker.
*Note: This software has not been developed at present.
2.3.3.3 Redundant Controller Set-Up
After making sure the 48VDC power has been removed from the unit, remove the two “Phillips” head screws from
the “Display” panel as above. Re-install the top “controller” printed board that was previously partially removed.
Using the circuit board retaining bracket, disengage the bottom “controller” board from its connector. Replace the
“Display” panel and secure it with the two “Phillips” head screws previously removed. Repeat step 3.3.2 for this
second “controller”. When the set-up is complete, remove the 48VDC applied to the system. Again open the front
“Display” panel and reseat the bottom “controller” circuit board. Replace the circuit board retaining bracket and
secure it in its final position using the two 6-32 “Phillips” head screws. Replace the “Display” panel and secure it to
the rack using the two 8-32 x 3/8” “Phillips” head screws. Set up is complete.
2.3.4
Power Module Installation
The power modules are designed to be “hot swap”. However, for initial start up, all of the power modules should be
installed. In a system where all of the module positions are not used, reinstall the previously removed blank panels in
these locations. Install the “power modules” and tighten the four thumbscrews on each module. Before turning on the
main source DC circuit breaker and utility AC circuit breaker (if used), make sure that all of the “power module” circuit
breakers (upper left-hand corner) of each module is OFF. Also verify the ON/Stand-by” switch on the “Display” panel
is in the OFF (down) position. The inverter plant usually supplies power to some type of distribution circuit breaker
panel. Confirm that all of these circuit breakers (loads) are OFF before starting up the inverter. After the DC input cable,
utility line cable, and output cable are properly connected and secured, the inverter system is ready to be turned ON.
2.3.5
Start-Up Sequence
Confirm that all power modules’ ON/OFF circuit breakers are set to the OFF position. On the LCD “Display” panel,
be sure inverter switch SW1 is set at OFF position.
page 2 — 8
Installation & Operation
Owner’s Manual
2.3.5.1 Power-Up Procedure
Turn the main source DC input circuit breaker ON to apply 48VC to the system. The “controller” boards and LCD
“Display” panels are now energized. The following message will be displayed (paragraph 4 of chapter 1 gives full
details of LCD readout):
Line 1:
Line 2:
INV:
BYP:
off
static
normal
AC LOW
If the system is equipped with two controllers, one controller will take control of the system, the other will be a backup. Assuming “Controller A” takes control of the system, the BYPASS Status LED (DS1) will be red, Inverter Status
LED (DS2) will be out, “Controller B” Bypass and Inverter LEDs (DS3, DS4) will alternately blink On and Off, red for
Bypass, green for Inverter. If “Controller B” takes control, its Status LEDs will be as for “Controller A” above.
If an external AC power source is used, turn on the source AC circuit breaker. After about 20 seconds the LCD
should display the following information:
Line 1:
Line 2:
INV:
BYP:
off
static
normal
normal
The “Status” LEDs will be as above, except the “Bypass” will be green if the AC input voltage is within proper limits
(voltage and frequency).
2.3.5.2 Powering Up the Inverters
DO NOT turn on the inverter switch SW1 yet! Turn the circuit breaker on each power module to the ON position.
The LCD “Display” panel is still displaying the above two lines. Now, everything is ready and the inverter switch,
SW1, can be turned ON (push-up). The “Status” LEDs will be as above, except that the “Inverter” indicator that was
out will now be green if the system is functioning properly. The inverter is now supplying the power to the system.
Using a voltmeter, verify that the proper voltage (100, 110, 115, or 120VAC) exist at the Power Distribution panel,
or 200, 220, 230, 240VAC exist if set for the higher output. System circuit breaker may now be turned ON.
2.3.6
De-Energizing the System
If the system is equipped with an AC input, turn off the main feed circuit breaker. Then turn switch SW1 to the
“Standby” position (push down). Next, turn all the power modules front panel circuit breakers OFF. Lastly, turn the
DC input supply circuit breaker OFF.
Installation & Operation
page 2 — 9
3.5 to 21 kVA N+1 Inverter
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page 2 — 10
Installation & Operation
Owner’s Manual
Maintenance
3.0
Scope
This chapter describes maintenance and service of MGE UPS Systems Modular Inverter System, including safety
instructions, preventive maintenance, descriptions of replacement kits, and service.
3.1
Safety Instructions
IMPORTANT SAFETY INSTRUCTIONS FOR INVERTER SERVICING SHOULD BE PERFORMED OR SUPERVISED BY QUALIFIED PERSONNEL ONLY.
WARNING
IMPORTANT SAFETY INSTRUCTIONS FOR INVERTER SERVICING SHOULD BE
PERFORMED OR SUPERVISED BY QUALIFIED PERSONNEL ONLY.
WARNING
DC input power to the inverter is normally from a bank of batteries with
potentially high short circuit current capability. Accidental welding and
severe burns are highly possible if mistake occurs during connecting or
disconnecting these conductors.
WARNING
The green grounding wire at the TB1-4 to E1 ground lug needs to be
removed, If the inverter is to be attached to AC input power, instead of an
AC free environment.
3.2
Preventative Maintenance
3.2.1
Preventative Maintenance Procedures
The following preventive maintenance routines should be considered as a minimum requirement. Your installation
and site may require additional preventive maintenance to assure optimal performance from MGE UPS Systems
static inverter system and its associated equipment. We strongly recommend a contract with MGE UPS Systems
Electronics Customer Support Services for preventive and remedial maintenance.
The technician or electrician performing preventive maintenance on the inverter must be familiar with the indicators,
control methods, and operation of the inverter as described in this manual. All power to the inverter must be removed.
3.2.2
Dust Removal and Exterior Cleaning
Ensure that all equipment is clean and free of loose dust, dirt, and debris. The exterior of all enclosures may be
cleaned with a mild solution of soap and water (only when unit is safely powered down), lightly applied with a lint-free cloth.
Maintenance
page 3 — 1
3.5 to 21 kVA N+1 Inverter
3.2.3
Air Intake Cleaning
Inspect the air intake and exhaust openings for blockage. Verify that air flows freely through the equipment. Clean
the air intake and exhaust openings with a vacuum and a soft brush.
3.2.4
AC Fan Replacement Procedure
Every five years, replace the two AC fans on the “Static Switch” front panel, (MGE UPS SYSTEMS part number 0422130). This is accomplish by removing all the DC and AC power to the unit by turning OFF the main AC and DC
source circuit breakers. Then perform the following steps.
3.2.5
◗
Remove the front panel from the “Static Switch” (panel with two fans), by using a #2 “Phillips” screw
driver to take out the four screws securing the panel to the “Receiver” rack. Unplug the two fan wires
at the “Static Switch” printed circuit board. Observe the position of the connectors on the fans and the
fan guard orientation. It is important that the new fans be installed in the same position as the old fans.
Remove the fans from the panel. Disconnect the wiring harness from the old fans, as it will be used
for the new fans.
◗
Install the new fans onto the panel, making sure the fan guard orientation is proper and the connector
location is correct. Install the wiring harness removed from the old fans.
◗
Install the fan assembly onto the “Static Switch”, making sure to plug fan’s back into the “Static Switch”
printed circuit board connectors. Secure the front panel in place by using the four “Phillips” head
screws previously removed.
◗
Power up the system in the normal way by making sure the “Display” panel ON/Standby switch is in
the “Standby” position, all of the power module circuit breakers are OFF before AC or DC power is reapplied to the system. Apply the 48VDC and the AC (if applicable), then turn ON each of the DC circuit
breakers on the power modules, then activate the system by turning ON the ON/Standby switch on
the “Display” panel.
DC Fan Replacement Procedure
Every five years, replace the DC fan in each power modules (MGE UPS SYSTEMS fan part number 43-153645-00).
This is accomplished by removing the power module from the receiver. Then perform the following steps.
page 3 — 2
◗
Remove the front panel from the power module by removing the six “Phillips” head screws securing
the front panel to the chassis, the two screws securing the top cover to the front panel (6-32 x _”
“Phillips” head screws), and the two screws hold the DC circuit breaker to the front panel. It should
not be necessary to remove the top cover.
◗
Remove the front panel, being careful to unplug the fan from the printed circuit board.
◗
Observe the orientation of the fan wires and the fan guard so that it will appear like all other power
module front panels. Remove the fan from the front panel by removing the four screws holding the fan,
panel, and fan guard together.
◗
Install the new fan in the reverse order of disassembly. When installing the front panel onto the
chassis, care must be taken to ensure the three LEDs project through the front panel. Install all ten flat
head screws.
◗
Make sure the circuit breaker on the front panel is in its OFF position.
◗
Install the module back into the receiver rack.
Maintenance
Owner’s Manual
3.3
Replacement Parts
Replacement parts are available from MGE UPS Systems. Contact MGE UPS Systems Customer Support Services
for ordering replacement parts. Having replacement parts on hand will prevent unnecessary delays in critical
service times.
3.4
Troubleshooting and Servicing
Should you encounter a problem in the operation of the inverter and need MGE UPS Systems to service your
equipment, it is recommended to leave the unit in its current state. Record message (if any) and color signals on
the LCD display and LED indicators on the “Display” panel, then call MGE UPS Systems Customer Support
Services at 1-800-225-7822 for assistance. Leaving the unit in its current state will facilitate Tyco field engineers to
troubleshoot and bring your equipment back on line more easily. If you cannot wait, you may want to consider the
following troubleshooting tips.
3.4.1
Installation Check
Often, operation problems are caused by incorrect installation or setup. Before turning the system on, review
Chapter 2 for instructions pertaining to your particular system. Use the checklist in Table 4-1 in this review. If the
system fails to operate properly after being turned on, all items in Table 4-1 need to be rechecked and verified to
make sure things are connected correctly.
Table 3-1: Installation Checklist (Installed item to be verified)
3.4.2
◗
Inverter System included static transfer switch
◗
DC input terminals have correct voltage polarity
◗
Utility input terminals have correct voltage connections
◗
AC output terminals voltage connections
◗
Input conductor size correct ampacity
◗
Output conductor size correct ampacity
◗
Correct output voltage selected in personalizations
◗
Correct frequency selected
◗
On/Off Line Inverter is on-line
◗
Automatic or manual start is selected
Inverter System Basics
AC Input Circuit Breaker Ratings
Inverter rating
AC breaker rating
3.5 kVA
7 kVA
10.5 kVA
14 kVA
17.5 kVA
21 kVA
30A
60A
100A
125A
150A
200A
3.4.2.1 DC Input Circuit Breaker
Due to tremendous amounts of short circuit current available (in excess of 1000Amps for as long as several
minutes!) from bank(s) of batteries, that supply electrical power to inverter systems, it is extremely important to
connect a properly sized DC circuit breaker at the DC input cable that feeds the inverter system. The following table
is provided as a guide for selecting the proper circuit breaker. Refer to 2.3.1.2 for DC input specifications.
Maintenance
page 3 — 3
3.5 to 21 kVA N+1 Inverter
Inverter rating
3.5 kVA
7 kVA
10.5 kVA
14 kVA
17.5 kVA
21 kVA
125A
250A
375A
500A
650A
750A
DC breaker rating
3.4.2.2 AC Output Circuit Breaker
It is not required, but highly recommended. A power “Distribution” panel is available from MGE UPS Systems at a
nominal cost. Order part number XXXXXXXXX, which will accommodate up to 24 single-pole circuit breakers,
“Square-D” QO type.
3.4.2.3 Cable Connection and Static Switch Module
All input and output connection terminals are mounted inside the built-in “Static Switch”. It is very easy to identify
this module by looking at a front panel that has twin cooling fans. This front panel can be opened with a #2 “Phillips”
screw driver. When making connection, always double check to make sure that DC cable goes to DC bus bars,
identified as (+) and (-). The utility cables go to a terminal block, 120/240VAC connects to TB1-2, NEUTRAL to TB1-4.
AC output is from TB1-1 (120/240VAC), NEUTRAL to TB1-3. One of the best ways to verify continuity is to use a DMM.
3.4.2.4 ON-LINE Mode
ON-LINE mode is the mode in which the load is powered by the invert system, not the utility. It will get clean,
transient free electrical power from the inverter system, which is producing the AC power from a DC power source.
3.4.2.5 OFF-LINE Mode
OFF-LINE mode is the mode in which the load is powered from the Utility power line (external AC input power). In
the event of a power failure, a static transfer switch will connect the system output to the inverter and activate the
inverter so as to provide continuous power to the load with no interruptions of power to the load.
3.4.2.6 Troubleshooting Guide
After having thoroughly reexamined the installation and setup of the system, and still found it un-operational, user
can follow Table 3-2 to identify a problem, its cause, and recommendations for fixing it.
Table 3-2: Troubleshooting
Problem
Possible Cause
Possible Solution
Display panel not illuminated
No power to system
Check AC % DC power sources.
No output voltage
SW1 not ON
Turn SW1 ON
System starts, then shuts
down almost immediately
Overload, or shorted
output.
Remove some of the load and
restart the inverter.
Power module LED turn red
Module faulted
Reset by recycling circuit breaker
Module temp. indicator on
Module fan failure
Replace module or cooling fan
3.4.2.7 Inverter Configuration
3.4.2.8 Battery Booster
Battery booster is a push-pull type converter on which average current-mode control scheme was employed for
better dynamic response. The circuit utilizes a high frequency transformer for obtaining a pair of +213.5/-213.5Vdc
output and for galvanic isolation as well.
page 3 — 4
Maintenance
Owner’s Manual
3.4.2.9 Dual Half-Bridge Inverters
In or to provide more choices of output voltage, two identical half-bridge inverters are used to produce either
120VAC or 240VAC depending on parallel or series connection of the outputs. A network that consists of a coupled
inductors and high frequency capacitors form a second-order low pass filter and is connected across at each
inverter’s output for removing PWM signal. See figure 4-4.
3.4.2.10 Average Current Mode Control
A microprocessor is employed in the inverter system to generate a reference sine wave via one of its three PWM
outputs. The PWM signal is filtered to make a clean sine wave. This sine wave is applied to a voltage error
amplifier.
Maintenance
page 3 — 5
3.5 to 21 kVA N+1 Inverter
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page 3 — 6
Maintenance
Owner’s Manual
Theory of Operation
This chapter describes the theory of operation of the S4 inverter system.
4.0
SCOPE
The following is a brief description of the mechanical configuration and how the S4 inverter system functions. It is not
intended to provide complete details of all of the circuits within the unit, but gives some details as to the function of each
block. The system is a modular 48VDC to 120/240VAC inverter, which consists of 3.5 kVA/3KW modules housed in a
“Receiver” cabinet. Inverter systems can be ordered with one to six power modules (3.5 kVA to 21 kVA). Inverter
systems are available in the following power levels: 3.5 kVA/3KW, 7 kVA/6KW, 10.5 kVA/9KW, 14 kVA/12KW, 17.5
kVA/15KW, and 21 kVA/18KW. The inverter is designed to be a N+1 redundant system. Redundancy, or increased
power capability can be added at a later date by adding more power modules. Figure 4.1 is a block diagram of a 21 kVA
inverter. Figure 4.2 is an electrical block diagram of the “Inverter” system.
“Receiver” Cabinet Configuration
See Figure 2-2 for System Component Descriptions of the 7 kVA. On the top left-hand side of the “Receiver” cabinet,
two “Controllers” printed circuit boards are installed, one on top of the other. On top left-hand side of the “receiver” is
an alarm relay printed circuit board. The top part of the “Receiver” cabinet is common to all power level configurations.
In a 21 kVA system, immediately below the “Controller” are three 5.25” high “Power Module” chassis. Below the three
power modules is a 5.25” high “Static Switch”. The “Static Switch” in an integral part of the “Receiver” as are the inverter
output EMI filters, AC input/output terminal block, AC output and back-feed current sensing transformers, and DC input
termination bus bars. Three more “Power Modules” are installed immediately below the “Static Switch”. In the “Static
Switch” area, provisions are made for the user to select either 120VAC or 240VAC output. This is accomplished via bus
bar strap selection on the output terminals of the EMI filter and positioning a jumper plug on the Static Switch gate driver
PCB, which is located on the side of the receiver.
4.1
“Receiver” Cabinet “Controller”
In the “Receiver” cabinet is a printed circuit board called a “Controller” which has a microprocessor (Intel 80C198KC),
Read Only Memory (Waferr Scale “PDS301), and other associated electronics. This “Controller” is the “brain” of the
system and operates the power modules and “Static Switch”. As an option, two “Controller” boards can be installed
which will provide redundancy. The “Controller” circuit boards are located in the top right hand side of the “Receiver”
cabinet. If the redundant option is selected, only one processor operates at a given time. If the operating micro should
“get lost”, that is, not go through the code string properly in the allotted 250 micro-seconds, its hardware “watch dog”
timer will expire, issue a reset signal, at which time the faulty micro will be disconnected from the system. The redundant
micro will become activated. The microprocessors has eight analogue inputs, thus it inspects the AC input voltage, AC
load voltage, AC output current, AC back-feed current, DC input voltage, DC input current, number of power modules
installed, and number of power modules operating.
4.2
LCD “Display” Panel
The processor front panel, called a “Display” panel has a two line, twenty character “Liquid Crystal Display” (LCD) and
a scroll switch. This will allow the operator to “scroll” through the display for reading the AC input voltage, frequency, AC
load voltage, DC input voltage, DC input current, output watts, percent load (higher of VA or Watts), number of power
modules installed, and number of power modules operating. Each processor has “STATUS” LEDs associated with it,
each LED being tri-colored. One STATUS LED is for Utility power, the other for inverter. Two red “blown fuse” indicators are located on the top right-hand side of the “Display” panel, which give the status of the output filter capacitor fuses.
These LEDs will be illuminated if a fuse is blown. There is a DB-9 connector for the RS-232 communication, and a
master inverter ON/Standby switch. This switch is a rocker switch and is recessed in the front panel so as to require
deliberate action by the operator to turn the system “ON” or to “Standby.
Theory of Operation
page 4 — 1
3.5 to 21 kVA N+1 Inverter
Figure 4-1: Block Diagram of the 21 kVA Inverter System
page 4 — 2
Theory of Operation
Owner’s Manual
Figure 4-2: Block Diagram of the S4 Inverter Power System
4.3
Alarm Relays
Located just to the left side of the “Controller” printed circuit board card cage is the “Alarm” relay board. This is a
plug in circuit board with a terminal block located on the front of the card. Wire routing to the card will be through a
knock out located near the DC input, AC input/output knock out landings. A small hole in the “receivers” sheet metal,
with a grommet that can be used to feed the wires up to the front of this printed circuit board. The board can be
pulled out part way so as to make easy connections to the terminal block and then slid back into its connector. An
optional alarm circuit board (pending) which will allow the board to “talk” to the processor board via the RS-232
communications port.
4.4
Installation Set-Up
A lap top personal computer (PC) is needed to set the system up when it is installed at the customer sight. Set up
involves selecting the AC output voltage for either 120VAC or 240VAC via copper bus bar strapping on the EMI filter
and jumper plug position selection on the “Static Switch” printed circuit board, which is located on the left-hand side
panel in the “Static Switch” area. Each power module has two inverter outputs of 120VAC each, which can be
connected in parallel for 120V or series for 240VAC. The PC is needed to tell the processor the output voltage
strapping so that it can calculate output power correctly. In addition, the output voltage level can be programmed,
either 100, 110, 115, or 120VAC. The 240V connection will be twice this level, that is, 200, 220, 230, or 240VAC.
In addition, the ON-LINE or OFF-LINE, 50Hz/60Hz, AUTOMATIC or MANUAL restart mode can be selected. The
customer MUST use the lap top PC and service software set up program to input the number of power module
positions available in the receiver rack so as to obtain the correct display readings. The correct “Burden” resistor
set is set at the factory. In addition, the DC current sensor used to measure the DC input current changes from
model to model, thus the “Controller” must be programmed to match the kVA rating of the “Receiver” cabinet.
Theory of Operation
page 4 — 3
3.5 to 21 kVA N+1 Inverter
4.5
DC Input Power Connections
The “Receiver” cabinet also contains the DC distribution bus bar system, which is called a “DC Raceway”. It
consists of a sheet metal enclosure with two copper bus bars, 1.5” wide, 0.125” thick. These bus bars have ELCON
connectors attached to them. The “power modules” have short bus bars projecting out the back of the chassis,
which supply the power to the module. These bus bars plug into the ELCON connectors. DC input wiring connections to the bus bars is in the “static switch” area. They are set up to accommodate three positive wires and three
negative wires of 2/0 or smaller gauge wire, terminated with two-hole lugs. Wiring to the “receiver” rack should be
by the “super flexible”, welding cable type wire for the five or six “power module” systems, standard wire for the one
to four “power module” systems. Within the “static switch” area, the negative bus bar passes through a “LEM” open
loop DC current sensor, HTA type. In a system, which has redundant “processors”, there will be two current sensors.
The model number of the “LEM” current sensors change, depending upon the number of “power module” positions
in the “receiver” rack. The “Controller” needs to be set up at the time of installation. This set up will be by a “lap
top” personal computer (PC) and field service software.
4.6
Inverter AC Output Distribution
The AC Raceway contains connectors for interfacing to the “power modules”. It consists of one or two printed circuit
boards housed in a sheet metal enclosure. These PCBs have the inverter AC output filter capacitors. These capacitors are connected to the AC output terminals and rated at 50uF, 250V, one capacitor for each 120VAC “power
module” output. Power output and control of the power module is through a rack and panel connector. These
connectors, one per power module position, have the control and AC output wires. Two 16Awg wires are paralleled
for each 120VAC output and return. AC output wires are identified as “120VAC” and “NEUTRAL” for the master
inverter, “ACHI” and “ACLO” for the 120V slave inverter. The output of these PCBs are connected to the EMI by
means of 10Awg colored wire. Neutral is “white”, 120VAC is “black”, ACLO is “blue”, ACHI is “red”. These wires
eventually end up connecting to the “EMI” filters, there being two 120VAC filters. “120VAC” and “Neutral” connect
to the bottom EMI filter, and “ACHI” and “ACLO” connect to the upper EMI filter. The output of the filters are
connected either in parallel to produce 120VAC or series to produce 240VAC. Copper straps perform this function
and easily changed by the user. The inverter is shipped from the factory connected for 120VAC, 60Hz operation.
The “AC raceway” PCB is connected to the “Controller” back plain via ribbon cable and also to the second PCB in
a two to six “power module” system. The “AC race way” has cover plates which will aid in EMI reduction and also
prevent service personal from making inadvertent contact with live power wires.
4.7
Power Modules
The power modules are self-contained DC to AC inverters, minus the output filter capacitors and control circuitry
(which is located on the “Controller” boards). These “power modules” should be viewed as voltage controlled
current sources (or sinks). The front panel of the power module has a 100A DC circuit breaker, which is used to
turn the power module ON and OFF. This is located on the top left-hand side of the front panel. The center has a
fan guard, which covers the air intake of a 24VDC cooling fan. The fan is operated at reduced voltage, 14V, so as
to increase bearing life. At elevated ambient, greater than 55C, full voltage is applied to the fan. The lower right
side of the power module has three “LEDs” to indicate the status of the module. The LED closest to the center of
the unit is a RED/GREEN indicator. When the module is turned ON, the LED will be GREEN if the power module
can function properly. If it turns RED, the module has a faulted. Faults are usually due to the power module not
providing the proper output current, or the internal DC voltages are to high, or the module is over temperature.
There are two “Temperature” LEDs located to the right of the RED/GREEN status LED. The center LED is AMBER,
which will light if the internal heat sink temperature is to high, greater than 77C. The far right side LED is a RED
and will light if the internal heat sink temperature is excessively high, greater than 88C. When this LED lights, the
power module will shut down and disconnect itself from the system. The power module “status” indicator will also
turn RED. Over temperature Red LED will remain illuminated until the DC circuit breaker is turned OFF. Fan sped
control, temperature warning, and over temperature indications are by mechanical temperature switches.
page 4 — 4
Theory of Operation
Owner’s Manual
Figure 4-3: Block Diagram of Power Module
Theory of Operation
page 4 — 5
3.5 to 21 kVA N+1 Inverter
Figure 4-4: Voltage and Current Waveforms of DC/DC Battery Booster
page 4 — 6
Theory of Operation
Owner’s Manual
4.7.1
Power Module Configuration
The power module output current is approximately 10A/volt when it is configured for 120VAC, 5A/volt when configured for 240VAC. Figure 4-2 to 4-4 are block diagrams of the power module. DC power enters the module via bus
bars and is applied to a small EMI filter (called a “PI filter”). The filter is designed to reduce the high frequency
switching ripple and noise on the battery bus. It consists of powdered iron bus bar chokes, aluminum electrolytic
and polyester capacitors. A DC current sensor (“LEM” LA 125-P used to control the battery booster), inrush current
control, and low DC voltage turn OFF circuitry is also located on this printed circuit board (PCB). The battery
voltage, 48V, is transformed to two separate, isolated +/-212VDC outputs, which is used by the inverters to generate
the AC output sine wave voltage. This “booster” is a Current Feed, Center Tapped, Push Pull (CFCTPP) converter
operating at 20KHz. Circuit connection is shown in Figure 4-4 and is as described below.
4.7.1.1 Battery Input
The positive battery input, after filtering, is connected to an input inductor, L1. The output side o of L1 is connected
to the center tap of a ferrite core transformer. The outside primary legs of the transformer are connected to Insulated
Gate Bipolar Transistors (IGBTs). The two secondary center tapped windings on the transformer are connected to
bridge rectifiers, which are located on the “Primary Snubber” PCB. The rectifiers then connect to an energy storage
capacitor bank. The capacitor bank voltage is regulated to produce two separate plus 212VDC and minus 212VDC
outputs. The capacitor bank (Capacitor PCB) connects to the inverter output IGBTs, which in turn, connects to the
output filter inductor, then to the output connect relays before connecting to the output filter capacitors in the AC
raceway by a rack and panel connector.
4.7.1.1.1 Battery Booster Operation
We will attempt to describe a typical “Battery Boost” switching cycle when the unit is operating properly. Figure 4-4
is a block diagram of the “booster”. First, both IGBTs are turned ON, thus creating a short circuit on the primary
winding of the boost transformer. Under this condition, the center tap of the transformer looks like it is connected
to the negative DC input battery terminal through the IGBTs. Battery voltage is now applied to the input inductor.
Current through the inductor builds up linearly as a function of time. The formula, V=L x dI/dT applies, where “V” is
the voltage applied across the inductor, “L” is its inductance, “dI” is the rate of change in the current, and “dT” is the
time increment. The choke’s inductance is about 35uHy. Ripple current is set to be near 18A at 48VDC input.
Ripple frequency is 40KHz, twice that of the operating frequency of the boost transformer. Under normal operation
at 48VDC input, the average battery current is 72Amps for full output of 3000 watts. Thus the current in the input
inductor is sweeping up and down between 64.5A to 82.5A at a 40KHz rate. When the LEM sensor, LA125-P
located on the input “PI Filter” PCB measures a peak current of 82.5A, the control circuitry turns off one of the IGBTs,
the other IGBT remaining ON. Because one of the IGBTs is now OFF, the current in the inductor will cause the
center tap of the transformer to ramp up to the near +78 volts in about 0.5uSec (due to the snubber circuit). Due
to the boost transformer’s turns ratio of 4:11, the voltage reflected to the primary center tap from the 212.5V
secondary will be near 78 volts ((212.5+1.35)*(4/11)=77.76). The transformer now has voltage impressed across it,
so power can be transferred to the output to charge up the output bus capacitors. The capacitor voltage will be
regulated to near 212.5VDC. Since the voltage on the boost choke is now reversed (output side at 78V, higher than
the input side at 48V), the current in this choke starts to decrease. Note that when one IGBTs is turned OFF, the
voltage on the collector of the OFF IGBT will be two times the center tap voltage, that is, 156V. When the choke
current becomes less than 64.5A, the IGBT that was OFF is turned back ON, thus both IGBTs are again ON and
the choke currents starts to build up again. This completes one half of the switching cycle. Next, the other IGBT
that was ON in the previous power transfer cycle is now turned OFF because the choke current reached the 82.5A
point, so power is again transferred to the inverters DC bus capacitors. The total time for the above switching cycle
is 50uSec, or 20KHz. The waveform applied to the boost transformer is a duty cycle modulated voltage, which
produces +/-212V on its output.
Theory of Operation
page 4 — 7
3.5 to 21 kVA N+1 Inverter
4.7.1.2 Inverter
The boost transformer has two secondary windings, 22 turns, center tapped at 11 turns. The two secondary
windings, which are rectified, make two separate outputs of +212.5V and –212.5V each. These DC voltages are
applied to a filter “Capacitor” PCB, which connects to the inverter IGBTs. The primary has eight turns, center tapped
at 4 turns. The secondary inverter DC bus voltage is regulated by a TL431 shunt regulator and an optical coupler,
which feeds back the control signal to the primary (battery) side electronics. The control of this Current Feed, Center
tapped, Push Pull booster is by what is called “Average Current Mode Control”. A write up of this basic technique
can be found in the old “Unitrode” application manual.
4.7.1.2.1 Dual Inverters
There are two identical inverters. The two inverters track one another because the inverters IGBTs are switched
ON and OFF at the same time and their DC bus voltages are nearly identical. Their outputs are applied to a two
winding (tightly coupled) output choke, which forces the two inverters outputs to track one another. The inverter’s
IGBTs switch between +212V and -212V at a 20KHz rate. To generate the 120VAC sine wave output voltage, the
“Pulse Width Modulated” (PWM) voltage (+/-212V) is filtered by an “L/C” filter, inductor being in the “power module”
chassis, the capacitor in the “receivers” AC raceway printed circuit board. If the duty cycle is 0.5, that is, the time
at the +212V rail is equal to the time at the –212V rail, the output will average out to zero (25uS at +212V, 25uS at
–212V). If the IGBT switch is at +212V for 37.5uS, at –212V for 12.5uS (duty cycle of 75%), then the output voltage
must average out to be +106V ((+212-V)*37.5uS =(V+212)*12.5uS), or V=106). To obtain 120Vrms (+/-170V peak),
the duty cycle must range between 0.099 to 0.909. The duty cycle can be calculated from the following flux balance
formula. V1*T1=V2*T2, and T1+T2=T, Duty=T1/T, where V1 is the voltage across the output choke when the
positive switch (IGBT, Q3) is ON and V2 is the voltage across the inductor when the negative switch (IGBT, Q4) is
ON. T1 and T2 are time at each supply rail, +212.5V or –212.5V. Control of the inverter is through what is called
“Average Current Mode Control”.
4.7.1.2.2 Inverter Output
The inverter’s output filter capacitors (50uF/250V on each 120VAC output) are located in the receivers “AC
raceway”. “Hot swap” of the power modules, while the system is operating, can be accomplished with no arcing of
the power module’s connector pins. If the capacitors were in each power module, connector arcing would occur
when the power module is installed or removed. Output fuses and disconnect relays are located in the output of
each power module. The relay driver is an “avalanche rated” high voltage FET, which is allowed to “avalanche”
during turn OFF of the relays. This will minimize the turn OFF time of the relays. The relays will not be energized
until the inverters DC bus voltage is greater than +/-190V. As indicated previously, fuses are placed in series with
each of these inverter output filter capacitors. In the event of a capacitor failure (generally shorting) the fuse will
blow, thus preventing system down. In a system with three “power modules”, a failure of one capacitor will not affect
system performance. The fuses are located in the “cold” side of the capacitors, that is, in the “NEUTRAL” and
“ACLO” side. A “blown fuse” indicator is provided on the front panel of the LCD display panel.
4.7.1.2.3 Inverter Control
As indicated earlier, the inverter is a voltage controlled current source. Control input to the power module is from
the Voltage Error Amplifier, located on the “processor” printed circuit board. Control voltage scale factor is approximately 10A/V in a 120VAC system. Thus the power modules can be easily paralleled to increase the output power
capability of a system. The control input to the power module is filtered, buffered by an operational amplifier, and
then applied to a current error amplifier, the other input to this current error amplifier is the output current of the
power module as sensed by a “LEM” LA125-P current sensor. This current error amplifier operates in what is called
“average current mode control”. The current error amplifier’s output is summed with a triangular wave sweep signal,
which sweeps between +5.2V and –5.2V at a 20KHz rate. This summed signal is now applied to a high-speed
comparator, the output of which control optically coupled IGBT gate drivers.
page 4 — 8
Theory of Operation
Owner’s Manual
4.7.1.2.4 Average Current Mode
If the inverter “current command” control signal can be made to control a current source (or sink), then the pole/zero
associated with the output L-C filter becomes a first order system, that is, a current source discharging or charging
a capacitor. It is much easier to stabilize this type of control loop. It also provides the needed current limiting
function. This type of system can be implemented by summing the inverter output current signal with the “current
command” signal and applying this signal to a current error amplifier. The output of this amplifier, along with a triangular “sweep” signal, is applied to a set of comparators, which operate the IGBT date drivers.
Here is a little history as to the problems associated with this approach. For an inverter to make a 120VAC sine
wave output (+/-170V peak) using a +/-213VDC bus voltage, the duty cycle must range between 8% to 92%. A duty
cycle of 50% will make the filtered output voltage zero. In the classical “peak” current mode control system, when
the duty cycles becomes greater than 50%, the famous half cycle instability problem will manifest itself. In “current
mode” controlled DC power supplies, the problem was resolved by adding what is called “slope compensation” to
the current feedback signal. This works well for a fixed output voltage power supply, but not for a variable output
supply. The “Unitrode” applications handbook, IC# 1051/1997 explains this instability in detail.
Later, another way was found to resolve this instability. If the “current command” signal is summed with the “output
current” signal, through another error amplifier, then applied to the comparators, the instability problem is resolved.
However, there are restrictions on this error amplifier. This amplified error signal is now applied to a set of comparators. The other input to the comparator is a linear sweep voltage. The maximum gain of this new current error
amplifier can be made fairly high. However, the slope of the amplified signal needs to be less than the sweep generators slope (dV/dT). If it greater than the sweep generators dV/dT, the output IGBTs will be turned ON and OFF
several times during a switching cycle. If this happens, the switching losses will become very large, resulting in
IGBT failures due to excessive heating of the transistor. The easiest way to analyze this function is to generate a
computer model and analyze the signal over the entire sine wave cycle for all load conditions, resistive, leading
reactive, lagging reactive, and computer loads with crest factors up to 3:1. This program was written in TURBO
BASIC, an old BORLAND software package, and is included in the appendix as INV3 kVA3.BAS. A copy can be
obtained from the writer at the following E-mail address: FRANK.MILLER@MGEUPS.COM. This program should
run using QUICK BASIC, whoever some of the SCREEN and PIXEL setting statements may need to be changed.
It is best to run this program in the pure DOS mode, not through “Windows”. “Windows” mode is about nine times
slower than the DOS mode, but it will work.
4.7.1.2.5 Inverter Sweep Generator
The sweep signal is obtains its signal from the battery booster LMC555CN oscillator through an optical coupler. This
40KHz signal is applied to another D flop (U19), which divides 40KHz signal by 2 to make a 20KHz square wave.
The sweep generator is almost identical to the sweep generator in the battery booster section, except it is set up to
produce +/-5.2 volt sweep voltage instead of +/-9.52 volt sweep signal. This sweep generator signal is summed
with the output of the current error amplifier through 4990 ohm resistors. This summed voltage, (Vveao+Vsweep)/2,
is applied to a set of window comparators, one comparator uses a positive 1.00V reference, the other uses a
negative 1.00V. The outputs of these comparators operate the photo drivers (HCPL-3120) which are located on the
“Power Supply/Driver” PCB. If the summed voltage is between –1.00V and +1.00V (dead band), neither comparator
will turn “ON” its respective photo drivers, thus all of the inverter IGBTs are OFF. This is needed to ensure that
“positive” and “negative” IGBTs are not ON at the same time. This could occur in an electrically noisy environment,
so the +/-1.00V “dead band” window will provide the needed noise immunity.
4.7.1.2.6 Fault Detection
For fault detection, the input “Current Command” signal, which is the output of the “Controller” Voltage Error
Amplifier, is summed with the output current signal as measured by the “LEM” LA 125-P sensor. It is then filtered
to remove the ripple and applied to a window comparator. Since the “output current” signal is out of phase with the
input “Current Command” signal, the filtered sum should be zero if the system is functioning properly. If the sum of
Theory of Operation
page 4 — 9
3.5 to 21 kVA N+1 Inverter
the two signals is not zero, then the inverter has failed. The inverter must be disconnected and shut down. Shut
down is accomplished by opening the inverters output relay as quickly as possible, turning of the drive to the IGBTs,
inhibiting the battery booster, and issue a signal to the “Controller” that the module is not OK via the MODSOK signal
line. A “minor” alarm signal will be issued by the “Controller” so the user will now that a fault has occurred. The
voltage error amplifier on the “Controller board (“current command” signal), will increase its output so that the
remaining power modules can output more current to make up for the current that was supplied by the disconnected
power module. The red/green “Status LED”, located on the power modules front panel, will turned RED. Two
additional LEDs are located on this front panel, an AMBER colored LED which will be illuminated if the internal heat
sink is hotter than desired (and a temperature warning signal, called “NOTEMP”, will be supplied to the “processor”.
If the internal heat sink temperature becomes excessive, a RED status LED will light and the power module will shut
down and a NOT OK signal issued to the processor. The circuit breaker located on the front panel of the power
module must be turned OFF, wait a few seconds, then turn it back ON to clear faults. Upon turn on of the circuit
breaker, the module will restart if no fault exist.
4.7.1.2.7 Internal Power Supply
The power supply in the “power module”, operates from the –48VDC input and is located on the “Power Supply,
Driver” printed circuit board. A 50/60 Hz bias transformer, which is located on the “Static Switch” circuit board, is
connected to the utility AC input terminal block. One of the secondary windings on this transformer is used to make
a -48VDC source, which is “Ored” with the battery –48VDC input. Thus the power supply will operate with either
battery power or AC utility power.
The supply is a 30W discontinuous mode flyback design, operating at 100KHz, which produces plus and minus
15VDC for the battery (primary) side circuits, plus and minus 15VDC for the inverter (secondary) side circuits, and
four isolated 30VDC outputs for the four isolated photo coupled inverter IGBT gate drivers. Control is via a
UCC3804N integrated circuit, which drives an IRF640 FET that is connected to a powdered iron “toroid” transformer.
The majority of the power is used to operate a 24V DC cooling fan. If the IGBT heat sink temperature is below 55C,
the fan will be operated at reduced voltage (+15VDC) so as to increase fan life. If the heat sink temperature exceeds
+55C, a mechanical thermal switch will close and the fan will receive about 26V (+15V and –11V via a resistor from
the –15VDC supply). This fan power is taken from the primary (battery) +/-15VDC supplies. The “Unitrode”
integrated circuits manual (now Texas Instruments) provides data as to the design and operation of UCC3804N chip.
4.8
Controller
This printed circuit board contains an “Intel” 80C196KC processor (U9), an Electrically Erasable Read Only Memory
(EEROM) (U8), a “Wafer Scale Integration, Inc.” PSD301 program memory chip (U10), which contains the operating
program in its Read Only Memory (ROM). It also has a Random Access Memory (RAM) section. The circuit board
also has two CMOS rail to rail quad operational amplifiers (U5, U6) which buffer the eight analog inputs to the
processor. Other circuitry includes a “watch dog” timer (U7), LED and relay driver (U11), power ON reset circuit
(U4), reference sine wave Pulse Width Modulator (PWM) filter (U12, U13, Q5, Q6), and voltage error amplifier
(U14). Power for the processor and other circuits is obtained by down regulating the -48V battery voltage. The
processor is referenced to the negative 48VDC input. The positive 78VDC input is connected to “ground” at the
user’s sight. Thus the negative DC input must be fused. There may be two processor PCBs in a system, so a flip
flop was implemented using photo-couplers (UU17, Q10). The processor that starts up first will takes control.
4.8.1
“Controller” Power Supply
The 48VDC battery voltage is applied to a 15VDC regulator circuit which is made up of a TL431ACP shunt regulator
chip and a TIP47 series pass transistor. The actual DC voltage is +14.97, +/-2%. This is applied to a LM7805
regulator chip to make the +5VDC operating voltage for the 80C196KC micro. Two other TL431ACP shunt regulators are placed in series so as to make +2.495V and +4.990V reference voltage for the processor’s eight bit A/D
converter. As indicated above, the signals to the eight analog inputs of the micro are buffered by a CMOS rail to
rail amplifier (LMC660) such that the input to the micro can not exceed the limits allowed by the processor manufacturer,
page 4 — 10
Theory of Operation
Owner’s Manual
zero to +5V. The +2.495V is used as the reference for the LMC660 amplifiers, signal transformers, which are used
to measure the AC input and load voltages, and AC current transformers.
4.8.1.1 “Controller” Input Signals
The DC current sensor used to measure the battery current is “LEM” HTA types and require +15VDC, return, and
–15VDC. We do not have a negative 15VDC supply, thus the LEM was offset by 15V. The –48VDC battery line,
which is called AGND (“Analog Ground” after fusing) was connected to the “LEM’s” –15V terminal, the “return” was
connected to +14.97V, and the +15V terminal connected to +30V. This +30V is quasi regulated by a 16V zener
(anode connected to the +14.97V) and NPN transistor, TIP47. The HTA-X00 sensors are set up to produce an
output of +4.00 volts at rated DC current. The model number of the HTA-X00 changes depending on the number
of power module positions available in the “Receiver” cabinet. The field service setup software is needed to tell the
micro how many positions are available so that the proper scale factor can be programmed into the EEROM.
4.8.1.2 DC Current Measurement
Below is a table of “LEM” model numbers to be used in the various receiver configuration.
Power Module
Positions
Model
Number
Current
Rating
Output
voltage
Max Current
Measurement
1
HTA-100
100A
4.00
137.8A
2
HTA-200
200A
4.00
275.6A
3
HTA-300
300A
4.00
4133.9A
4
HTA-400
400A
4.00
551.2A
5
HTA-500
500A
4.00
689.0A
6
HTA-600
600A
4.00
826.8A
The actual maximum operating current is less than the rated current. For zero DC input current, the output of the
HTA-X00 sensor will be at zero with respect to its “return”, which is actually connected to +14.97V. At full rated
output current, the HTA- sensor will output 18.970V (14.97+4.00 =18.97). Sensors are intended to measure AC
current, thus have at lease a 141% DC measurement capability. The LMC660 amplifiers are set up to range
between +4.50V to +0.50V (HTA-100 measuring range of zero to +125A). The other HTA sensors produce the same
voltage swing for different current levels. The Micro scale factor is based on the number of power module positions
available, not power modules installed in the “Receiver” cabinet, and must be set up properly.
4.8.1.3 Analog Inputs
The table below identifies the eight analog inputs to the processor. The input will make a voltage that ranges from
+4.50V to +0.50V at the appropriate input port of the processor. Voltages to the analog input terminal of the
processor, which are between 0.10 and 0.25V are usable. Voltage above 4.75V may not be processed since the
minimum Vcc supply voltage to the processor is 4.75V via a linear regulator, LM7805CT or LM340T5.0.
Theory of Operation
page 4 — 11
3.5 to 21 kVA N+1 Inverter
Function
Micro
port
Input at
0.250V
Input at
0.500V
Input at
4.500V
Input at
4.750V
Notes:
I backfeed
P0.0
Ibat, battery current.
P0.1
No. modules installed.
P0.2
See below
No. modules OK.
P0.3
See below
Vbat, battery voltage.
P0.4
66.613
65.030
39.696
38.113
Vacin, RMS input volts.
P0.5
143.51
127.52
127.52
143.51
Iacout., rms load current.
P0.6
30.23
34.02
90.68pk
102.05pk
Vacout, RMS load volts.
P0.7
143.51
127.52
127.52
143.51
V>+/-1V
133.27
125.45
2.00
-5.72*
HTA-100
In the chart above, (*) indicates negative current, however actual current ranges is always zero or greater. Zero
current voltage is +4.565.
MODSIN and MODSOK voltage is a function of the number of modules installed. The chart below gives the
expected voltage at P0.2 and P0.3. In each power module, there is a 10K resistor connected between MODSIN
and AGND and also between MODSOK and AGND for each micro.
MODSXX
0
1
2
3
4
5
6
P0.2, 3
0
1.4926
2.4917
3.2056
3.7412
4.1580
4.4914
4.8.1.4 Digital Inputs
The power module temperature warning is via a photo coupler connecting the NOTEMP terminal to AGND for each
processor. The processor will energize the “minor alarm” relay for this condition.
4.8.1.5 Alarm Relays
The microprocessor has a three alarm outputs:
◗
Major alarm will be by the de-energizing the alarm relay. Major alarm will be issued if the inverter can
not support the output load requirement.
◗
Minor alarm, which alerts the operator to a potential problem. Voltages or temperatures which are not
within limits will cause this alarm.
◗
“Utility” alarm relays will be energized when the AC input voltage to the inverter is not within its proper
operating limits (+10%, -15%) or the utility voltage frequency is not within limits, 50 +/-3Hz, or 60 +/3Hz. If Utility voltage is present and the system is set up to operate in the “OFF-LINE” mode, the
“Static Switch” will be turned ON so as to support the load.
4.8.1.6 “Watch Dog” Timer
The processor operates from a 16MHz crystal connected to its oscillator terminals. None of the internal ROM in the
processor is used. The processor must go through the code string every 250uSec. If it fails to do this, it means
that the program is not being followed and is probably “lost”. A hardware “watch dog” timer is implemented with R’s,
C’s, diode, and a “Schmitt” hex inverter gate. As long as the input to the timer is continuously reset, the micro will
operate normally. If it is not reset, a NMI signal is issued and the micro will load in the default values from the ROM.
If a redundant processor is available, the faulted micro will be inhibited and the redundant micro will be allowed to
operate via the optically isolated cross-coupled gates.
page 4 — 12
Theory of Operation
Owner’s Manual
4.8.1.7 High Voltage Drivers
The processor PCB also has a high voltage transistor array (ULN7002), which is used to control the tri-colored
“STATUS” LEDs and “alarm relays”. The LEDs are powered directly from the 48V input bus through dropping
resistors. The transistor array shorts out the appropriate Red and/or Green LED to produce the Green, Amber, or
Red color. The “Alarm” relays operate directly from the +48VDC supply, thus the high voltage driver is needed.
4.8.1.8 Under Voltage Detector
The “Controller” circuit board also has an under voltage detector (U4) which inspects the +14.97V regulator voltage.
The “reset” line will be held low until supply voltage is greater than +12.275V. A “reset” signal is issued if the voltage
falls below this level.
4.8.1.9 Sine Wave Reference
Sine wave reference signal is obtained from the 80C196KC processor, which has three PWM outputs. One of these
is used to generate the phase locked sine wave reference voltage. The amplitude is set at the time of calibration
and the calibration constants are stored in the EEROM. Default values are in PSD301 ROM. The output of this
PWM signal is buffered (U7) and applied to an optical coupler (U12). The coupler provides isolation between the
primary (battery) side circuitry and the secondary (AC output) circuitry. The optical couplers output amplitude is
stabilized by a +5V regulator (U13) and FET switches (Q5, Q6) and then filtered by a two stage R-C filter (R60, R61,
C40, R62, C41) than level shifted and phase corrected by C42 and R63. The buffered (U14) reference sine wave
is now applied to the system “Voltage Error Amplifier”, U14 through ad DC blocking capacitor. Feedback to the error
amplifier is from the output of the 120VAC inverter, connections being made at the input terminals of the EMI filter.
An optically coupled FET switch is placed in series with the output of the Voltage Error Amplifier so as to be able to
disconnect it from the system in the advent of a failure in the processor. Isolation resistors are provided in the
“Voltage Error Amplifiers” output that goes to each power module. This will prevent a system failure if one of the
control lines should become shorted to ground.
4.8.1.10 “Display” Driver
Output to the LCD display is isolated by means of diodes. The LCD is powered from the 48V input supply and
regulated via a 5.1V zener and diode so as to produce +5.7V for operating the LCD module. This compensates for
the isolation diodes in the output of the LCD signal lines. LCD actually operates at +5.0VDC.
4.8.1.11 “Controller” Selection
The cross-coupled optical coupler (U17) and FET (Q10) generate the MASTER control signal (I/O port P1.4). A “1”
to the processor tells it that it is in control. A green LED located on the processor PCB will be illuminated if the
processor is operation. The LED can not be seen when the LCD panel is in place.
4.8.2
Static Switch
The “ Static Switch” consists of a parallel connection of a dual Silicon Controlled Rectifier (SCR) module, anode of
SCR1 connected to the cathode of SCR2, anode of SCR2 connected to the cathode of CR1. This module is mounted
on a heat sink, 12” long, 5.15” high, 1.5” thick. The heat sink is cooled by two AC powered fans. The purpose of the
dual fan is for redundancy. If one of the fans should fail, the other fan can cool the SCR module until the unit can be
serviced. The “Utility” AC input, if available, will be connected to a terminal block TB1-2. The system output is on
TB1-1. TB1-2 and TB1-4 are AC returns. TB1-2 is connected to the dual SCR module. The other side of the SCR
module connects to TB1-1 and also to the “EMI” filter, which in turns connects back to inverter output. Several
different SCR modules used in the system. The current rating of the modules changes with respect to the number
of power module positions available in the “receiver” rack. The one and two module system will utilize an IXYS
“MCC72-16io1 B”, the three and four module system will utilize an IXYS “MCC132-16io-1”, the five and six module
system will use an IXYS “MCC220-16io”. A 480V “Metal Oxide Varistor” (MOV) is connected across the SCR module.
Theory of Operation
page 4 — 13
3.5 to 21 kVA N+1 Inverter
4.8.2.1 Static Switch Driver
On the right-hand side panel of the “receiver” cabinet is the “Static Switch” gate driver printed circuit board. This
board serves two functions. One, it has a 120/240VAC, 50/50Hz bias transformer mounted to it which provides the
auxiliary 48VDC for operating the “Controller” and “LCD” “Display”. In addition, the transformer has two low voltage
AC windings, which are used to make two isolated DC voltages, that are used to turn ON the “Static Switch “ SCRs.
This transformer is connected to the “Utility” AC input. Selection of the 120VAC or 240VAC connection is by means
of a jumper plug. The printed circuit board has two small transformers, which are used to measure the AC input
and AC output voltage. Selection of the input voltage range, 120/240VAC, is accomplished by the same jumper plug
as used to select the operating mode for the bias transformer. Each transformer has two secondary windings, one
for each “Controller” of a redundant system.
When the “Static Switch” SCR module is turned ON, a connection between the “Utility” AC input and the inverter
output. Under normal conditions, the SCR module is ON at all times and commanded OFF by the “processor”. Thus
a “fail safe” mode of operation is provided. When the power to the load is from the “inverter” system, the “Controller”
will turn ON an optical coupler on the “Static Switch” gate driver board. When these photo couplers are turned ON,
the gate drive current will be turned OFF, thus the SCR module will disconnect the “Utility” AC input.
Two isolated, low voltage, DC supplies were created, one for each SCR in the dual SCR module. The voltages will
range between 5 to 10 VDC, depending upon the “Utility” input voltage. “P- channel” FETs and resistors are
connected from this DC supplies to the gates of the SCR module. The FETs are connected so that they are ON.
That is, its “source” is connected to the positive supply terminal, the FETs “gate” to the negative supply through a
resistor. The FETs “drain” connects to the SCR gate through a resistor. Photo couplers are connected between the
“source” and “gate” of each FET. When the photo couplers are ON, the FET gates are shorted out, thus the FETs
are OFF. With no gate drive current, the SCR modules are OFF.
4.8.3
Current Sensing
AC current transformers are used to measure the system output current and also to measure “back-feed” current.
They are “Square-D” devices with a 650:1 turns ratio. There are four current transformers in a system that has a
dual “Controller”. These current transformers are located on the wire going to TB1-1 (output terminal) and TB1-2,
(input terminal).
4.8.3.1 Output Sensing
The “burden” resistors for the AC output current transformers are located on the “back plane” printed circuit board.
This back plane is used to interconnect the “processor” PCBs, AC raceway, and “Alarm” relay PCB. A “receiver”
cabinet, which can accommodate six power modules, will have six parallel 14.3 ohm resistors for each AC output
current transformer. A cabinet, which can accommodate five power modules, will have hive parallel resistors. A
system with four power modules will have four parallel resistors, etc. The number of parallel resistors depends upon
the number of power module positions available in the rack, not the number of modules to be installed. A system
which has two “:Controller” boards (redundant mode) will have two sets of burden resistors. Selection of these
resistors will be via a 12 position “DIP” switch, located on the “back plane”. This switch is factory set and should
not be changed by the customer. A one module system, switch position 1 and 12 will be turned ON, for a two module
system, switch positions 1, 2, 11, and 12 will be ON, for a three module system, switch positions 1, 2, 3, 10, 11, and
12 will be ON. All switches will be set ON for a six module system.
4.8.3.2 Back-Feed Current Sensor
Back-feed current transformer is installed on the AC input wires. This device is necessary to determine if the “Static
Switch” is functioning properly. If a SCR in the “Static Switch” should fail in the shorted mode, power from the inverter
could be applied to the AC input terminals. This would present a safety hazard for service personnel working on the
“utility” wiring. CSA and UL require back-feed protection. This is accomplished by the use of an AC current transformer
that will sense any current flowing through the SCR when it is OFF. If current is detected, the inverter will be shut down.
page 4 — 14
Theory of Operation
Owner’s Manual
The output of this current transformer is clamped to a maximum of +/-1.1V by means of back-to-back diodes, which
is in parallel with a high value burden resistor. This signal is supplied to the “Controller”. If back-feed current should
be detected when the inverter is operating, the system will be shut down, that is, latched OFF. Reset us accomplished by cycling the system OFF ON/ switch on the LCD display panel. Current transformers are connected to
the “back plain” via an eight-pin connector. Four of these pins are used as interlock connections, which will prevent
the inverter from operating if the current transformers are not connected.
Theory of Operation
page 4 — 15
3.5 to 21 kVA N+1 Inverter
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page 4 — 16
Theory of Operation
Owner’s Manual
Glossary
Appendix A
Symbols
Definition/Meaning
@
At.
/
And/or.
+/-
Plus or Minus.
#
Number.
°C
Degree Celsius.
°F
Degree Fahrenheit.
Ø
Phase angle.
W
Ohm; unit of resistance.
®
Trade Mark.
2nd
Second.
AC or ac
Alternating current, also implies root-mean-square (rms).
Ambient Temp.
Temperature of surrounding air.
Ambient noise
Acoustical noise of surrounding environment.
ANSI
American National Standard Institute.
AWG
American Wire Gauge.
Breaker
Electrical circuit interrupter.
BYPASS
See “Static Transfer switch”.
BYPASS mode
See “off-line mode”.
Carrier
The company or individual responsible for delivering goods from one location to another.
C
Common.
CB
Circuit breaker.
Conduit
A flexible or rigid tube enclosing electrical conductors.
C.S.S.
Customer Support Service.
Current rating
The maximum current that a conductor or equipment can carry reliably without damage.
dBA
Decibel Adjusted.
dBrnC
Decibel above reference noise.
Glossary
page g — 1
3.5 to 21 kVA N+1 Inverter
DC or dc
Direct current.
Digital Meter
The LCD display on the front panel of inverter system.
Earth ground
A ground circuit that has contact with the earth.
Electrician
Refers to an installation electrician qualified to install heavy-duty electrical components in
accordance with local codes and regulations. Not necessarily qualified to maintain or repair
electrical or electronic equipment.
Freq.
Frequency.
Frequency slew rate
The change in frequency per unit of time. Given in term of Hz per second (Hz/sec.).
GND
Ground.
Hz
Hertz, frequency measurement unit, 1Hz is one cycle per second.
Inverter mode
See “on-line” mode.
I
Current.
IEC
International Electrotechnical Commission.
IEEE
Institute of Electrical and Electronic Engineers.
Input branch circuit
The input circuit from the building power panel to the equipment.
Inverter
An electrical circuit that generates an AC voltage source from a DC voltage source.
kVA
KiloVolt-Ampere; is equal to 1000 Volt-Ampere.
L
Line.
LCD
Liquid-Crystal Display unit.
LED
Light Emitting Diode.
Mains or Mains 1
Main AC input source.
Mains 2
Bypass AC input source.
mA
milliampere.
MAX.
Maximum.
MCM
Thousand circular mil; standard wire sizes for multiple stranded conductors over 4/0 AWG in
diameter. M is from Roman numerical system indicating 1000.
Module
Refers to individual power inverter module.
N
Neutral.
NC
Normally close.
NO
Normally open.
NEC
National Electrical Code.
page g — 2
Glossary
Owner’s Manual
NFPA
National Fire Protection Association.
NO. or No.
Part number.
On-line mode
Inverter output power is the primary energy source to load.
Off-line mode
Inverter output is off, and the load connected at the inverter output receives power from utility
line via a static transfer switch or maintenance bypass relay.
OSHA
Occupational Safety and Health Agency.
PWM
Pulse Width Modulation.
SCR
Silicon controlled rectifier.
Shipping damage
Any damage done to an article while it is in transit.
SPDT
Single Pole Double Throw.
Static Transfer
An solid state switching mechanism electronically controlled to pass AC power directly from the
utility to an output load.
Technician
Refers to an electronic technician qualified to maintain and repair electronic equipment. Not
necessarily qualified to install electrical wiring.
Test connector
DB-9 type connector on the LCD panel allowing MGE UPS Systems Customer Support Service
technician to access programmable and diagnostic features of the system.
VA
Volt-amps, unit for apparent power measurement, equal V x I.
VAC or Vac
Voltage of AC type.
VDC or Vdc
Voltage of DC type.
Glossary
page g — 3