Industrial-Grade Starters. Trane Drives, CVHG, Starters, CVHF, Electrical Components, CVHE, CDHG, CDHF

CTV-PRB004.book Page 63 Sunday, December 18, 2011 6:39 PM

Starter Options

Figure 44. Bottom-entry, multiple, across-the-line starter arrangement (2.3–6.6 kV) main bus auxiliary section main bus

X- Line starter X- Line starter

92"

30"

24" 72" incoming line power

Multiple starter lineups for 10–13.8 kV starters

Side-by-side starter lineups are available for 10–13.8 kV starters. Contact CenTraVac Field Sales

Support for dimensions and availability.

Industrial-Grade Starters

High-fault starters can be selected independently of the Enhanced Electrical Protection Package.

High-fault, remote, solid-state starters (IHRS)

• NEMA 12



960 amps

• Flanged disconnect

• 100,000 amps short-circuit current rating

• SAE HS-1738

• Up to 600 volts

High-fault, remote, wye-delta starters (HRWD)

• NEMA 1,961 to 1,600 amps

• Non-flanged disconnect

• 85,000 amps short-circuit current rating

• Up to 480 volts

Medium-voltage remote starters (2,300–6,600 volts)

• Across-the-line, primary reactor, and autotransformer

• NEMA 12 option

• SAE HS-1738 option

• Flanged disconnect

CTV-PRB004-EN 63

CTV-PRB004.book Page 64 Sunday, December 18, 2011 6:39 PM

Starter Options

Figure 45. High-fault wye-delta starter

Enhanced Electrical Protection Package

Applications that require the utmost reliability and rugged construction may prompt the selection of the Enhanced Electrical Protection Package. CenTraVac chillers equipped with the Enhanced

Electrical Protection Package are constructed to NEMA 4 guidelines and feature completely enclosed wiring in seal-tight conduits and junction boxes. The Enhanced Electrical Protection

Package control panel also includes some additional installation features and layout improvements. The purge is also upgraded to NEMA 4 construction. The entire chiller is siliconefriendly —all silicone is encapsulated and non-volatile so it does not affect any industrial and/or chemical processes.

Figure 46. CenTraVac with Enhanced Electrical Protection Package (AdaptiView unit controller)

64

Note: Unit shown with optional, unit-mounted control power transformer (below motor terminal box).

CTV-PRB004-EN

CTV-PRB004.book Page 65 Sunday, December 18, 2011 6:39 PM

Starter Options

These and other features listed in the following section allow the CenTraVac to meet or exceed the rigorous criteria of the Society of Automotive Engineers “Standard for Electrical Equipment for

Automotive Industrial Machinery, 2002 Edition” (SAE HS-1738). HS-1738 provides requirements and recommendations relating to the electrical equipment of machines so as to promote:

• safety of persons and property

• consistency of control response

• ease of maintenance

Enhanced Electrical Protection Package Purge

• NEMA 4 construction

• Seal-tight conduits

• Sealed motor terminal box

• Totally Enclosed Fan Cooled (TEFC) pumpout motor

Enhanced Electrical Protection Package Control Panel

• NEMA 4 construction

• accessory port circuit breaker

• screw-type terminal block connections

• welded seam construction

CTV-PRB004-EN

Enhanced Electrical Protection Package Chiller Enhancements

• SAE HS-1738

• Warning markings

• Phenolic (permanent) labels on control devices

• Silicone-friendly to industrial processes—all utilized silicone is encapsulated and non-volatile

• Polycarbonate junction boxes listed NEMA 4X

65

CTV-PRB004.book Page 66 Sunday, December 18, 2011 6:39 PM

Starter Options

66

Enhanced Protection (EPRO)

The Enhanced Electrical Protection Package includes the EPRO package, which includes sensors and transducers that enable the following chiller protection features:

Enhanced condenser-limit control.

Factory-installed condenser-pressure transducer with interconnecting piping and wiring provides enhanced high-pressure cutout avoidance by energizing a relay to initiate head relief.

Note: This protection is in addition to the standard high refrigerant-pressure safety contact.

Compressor-discharge refrigerant temperature protection.

Factory-installed sensor and safety cutout on high compressor-discharge temperature allows Tracer AdaptiView to monitor compressor discharge temperature and display the temperature at the chiller controller and at

Tracer Summit™.

Bearing oil temperatures.

Factory-installed sensors allow high-temperature safety cutouts to monitor the leaving bearing oil temperatures and display the temperatures at the chiller controller and at Tracer Summit.

The high bearing-temperature cutout is fixed at 180°F (82.2°C). If either bearing temperature violates the cutout, a latching (manual reset) diagnostic is generated.

Enhanced Electrical Protection Package Options

In addition to the above standard elements, customers who purchase the Enhanced Electrical

Protection Package have additional options. These options can be applied to remote-mounted medium-voltage starters, both from Trane and from other starter manufacturers.

CPTR, Control-Power Transformer (Enhanced Electrical Protection Package option).

4 kVA control-power transformer mounted on the chiller (480 to 115 volts)

• Flanged disconnect

• Fused primary and secondary power

• Secondary fuse status indictor (blown or not-blown)

• UL 508 Type 12 construction

• Unit-mounted and factory-wired

SMP, Supplemental Motor Protection—Medium voltage only (Enhanced Electrical

Protection Package option).

A separate enclosure mounted to the motor includes:

• Surge capacitors

• Lightning arrestors

• Zero-sequence ground fault

Other features:

• UL 347 tested Type 12 construction

• Field-accessible terminal block for trouble-shooting via panel

• Unit-mounted and factory-wired

CTV-PRB004-EN

CTV-PRB004.book Page 67 Sunday, December 18, 2011 6:39 PM

Starter Options

When the SMP option is selected, the medium voltage starter must be remote.

Note: Additional “top hat” provisions may need to be field-supplied to allow for shielded cable with stress cones (field-provided).

DMP, Differential Motor Protection (selectable with the SMP option).

DMP replaces the zero-sequence ground fault protection. Instead, it uses a flux-summation, self-compensating differential protection scheme for a quicker and more precise removal of line power during a fault

(see “Differential motor protection,” p. 75 ).

Note: DMP is available only for 1,062 kW and larger motor sizes up to 5,000 volts.

Figure 47. Supplemental motor protection enclosure with DMP option

1

CTV-PRB004-EN

2 3

1.

Lightning arrestors

2. Surge capacitors

3. SEPAM module (Square D Electrical Protection and Metering)

Implications of the Enhanced Electrical Protection Package and SMP option on customer-supplied starters (SBO).

Most of the accommodations that would need to be met by the customer who wishes to use a non-Trane starter are provided with the Enhanced Electrical

Protection Package and the SMP option.

Note: Trane-supplied starters already include these items.

The supplemental motor-protection enclosure will include:

• Primary, single-stage current transformer in lieu of primary and secondary CTs

The oversized control panel will include:

• Second-stage PTs, 115 to 30 volts, for medium-voltage applications only

• Three-pole disconnect

• Industrial terminal block for field control and control-power connections

67

CTV-PRB004.book Page 68 Sunday, December 18, 2011 6:39 PM

Starter Options

68

The customer is still responsible for providing primary potential transformers for medium voltage.

Criteria for the Enhanced Electrical Protection Package.

The Enhanced Electrical Protection

Package may be selected for CenTraVac chillers that meet the following criteria:

• Single compressor (no Duplex™)

• 60 Hz only

• 080, 142, 210, and 250 shells in all short, long, and extended combinations

• Motor frame sizes 440E, 5000, 5800, and 5800L, which correspond to approximate chiller capacities from 450 to 2,000 tons

• NEMA 1 unit-mounted starters can be accommodated. Contact CenTraVac Field Sales Support for details.

Refer to CTV-PRC007-EN ( Product Catalog: EarthWise™ CenTraVac™Water-Cooled Liquid Chillers ) for information on possible special configurations.

Note: Placing a unit-mounted starter on an chiller equipped with the Enhanced Electrical

Protection Package negates the chiller’s NEMA 4 rating and changes it back to a standard

NEMA 1 rating.

Industrial paint.

Trane offers a two component, catalyzed, executive beige high-solids epoxy coating paint system to meet or exceed the performance of the US Department of Defense

(USDOD) military specification MIL-PRF-22750F.This paint has a volatile organic compound (VOC) content less than 2.8 lb/gal (335.6 g/L). It offers protection and resistance to fluids, adhesives, solvents, heat, and weather. We recommend that it be used with the “Enhanced Electrical

Protection Package,” p. 64 ; it is priced separately.

Starters by Other Manufacturers (SBO)

Occasionally a customer chooses to reuse an existing starter or purchase a starter directly from a starter manufacturer. While this can be accommodated, it requires careful coordination between theTrane sales representative and the owner, engineer, and starter manufacturer because generic or existing starters are not compatible with the Trane ® chiller control panel.

Non-Trane starters must be modified with the proper components and control wiring before they are connected to a Trane ® chiller. Existing starters should be modified by the owner’s representative; new starters should modified by the starter manufacturer. Trane assumes no responsibility for the design, construction, compatibility, installation, startup, long-term support, and will not maintain records or drawings for the resulting starter.

Trane provides a Starter by Others specification, which provides the information required for others to build a starter that is compatible withTrane ® centrifugal compressor motors and controls.

When a non-Trane-provided starter is used, it must be modified to conform to the appropriateTrane

Starter by Others specification. SBO specifications are revised on a regular basis, so it is important to obtain the correct version before building or modifying a starter by others.

It is also important to include the cost of conversion when determining the total cost of a non-Trane starter; therefore, the owner should be provided with the appropriate SBO specification before the decision is made to reuse or purchase a non-Trane starter. Components required for conversion include but are not limited to:

• 4 kVA control-power transformer (1)

• Primary current transformers (3)

• Secondary current transformers (3)

• Primary potential transformer (1) for medium-voltage starters

• Secondary potential transformers (3) for medium-voltage starters

• Other optional starter equipment, e.g. power factor correction capacitors, as required by the specification

TheTrane ® chiller control panel integrates the chiller, motor, and starter into a single control and protection system. Therefore, non-Trane starters do not require an additional motor-starter protection package. If a non-Trane starter includes a protection package, the protection package

CTV-PRB004-EN

CTV-PRB004.book Page 69 Sunday, December 18, 2011 6:39 PM

Starter Options must be disabled or the sensitivity of all the starter trip levels must be readjusted so that theTrane ® control panel acts as the primary protection for both the chiller and the starter.

Chillers used with non-Trane starters must ship with a special control panel to accommodate the non-Trane starter. It is the responsibility of theTrane sales representative to select the “Starter by

Others (SBO)” option when pricing the chiller and to assure that the non-Trane starter is built according to the proper “Starter by Others” specification.

Note: The Enhanced Electrical Protection Package can simplify the procedure for using a non-

Trane starter; see “ Implications of the Enhanced Electrical Protection Package and SMP option on customer-supplied starters (SBO) ,” p. 67 .

In summary, when a customer wants to buy a starter from a manufacturer other than Eaton Cutler-

Hammer ® , the procedure is as follows:

1.

Price the appropriate customer-supplied starter.

2. Provide a copy of the “Starter by Others” (SBO) specification S6516-0513 from CenTraVac Field

Sales Support to the customer/starter manufacturer. This specification lists the allowable starter types.

3. Inform the customer that Trane assumes no responsibility for the design, construction, compatibility, installation, startup, long-term support, and will not maintain records or drawings for the resulting starter.

Power Factor and CenTraVac Chiller Motors

CenTraVac squirrel-cage induction motors normally have an uncorrected full-load power factor of

88 to 92 percent.The power factor decreases slowly as the motor’s torque output drops from full load to approximately 50 percent, and then falls more rapidly at lower loads. If the full-load power factor is corrected to 95 percent, the entire curve shifts upward and the corrected power factor remains at a high value ( Figure 48, p. 70 ).The current (amps) for a motor with a corrected power factor is lower than the current for a motor with an uncorrected power factor.

In some cases, a power factor greater than 95 percent is specified for “all load ratios above

40 percent” or at a particular operating point. Multiple-capacitor arrangements with an elaborate switching mechanism can provide this level of correction without overcorrecting by “cycling” various capacitor combinations on and off as motor loading dictates; however, this arrangement is complex and its cost may be prohibitive.

Typically, specifications stipulate a corrected power factor of 95 percent at full load.This results in an economical application that balances the first cost of the capacitors with the benefits of a higher power factor.

Several equations are helpful:

ApparentPower(kVA) =

ActualPower(kW)

PowerFactor

=

Volts x Amps x



3

1000

ActualPower(kW) =

Volts x Amps x



3 x PF

1000

CTV-PRB004-EN 69

CTV-PRB004.book Page 70 Sunday, December 18, 2011 6:39 PM

Starter Options

Figure 48. Typical CenTraVac chiller-motor power factor

70

PFCC Placement and Sizing.

PFCCs may be installed at various locations in the power supply network. Utility companies install capacitor banks on their distribution feeders and substation buses. These capacitors correct for the utility’s reactive loads and for other large reactive loads, such as those found in business or industrial areas.

When utility customers correct for the reactive loads in their facilities, they usually install PFCCs at the facility’s electrical service entrance or at the individual loads within the facility. Connecting the PFCCs at the service entrance corrects reactive loads throughout the facility.This strategy can be advantageous if the facility contains a large number of small reactive loads—but it can also be costly. Successful implementation requires expensive hardware to monitor the power factor as loads are added to and removed from the distribution system, then switch capacitors on- and offline accordingly.To avoid this expense, PFCCs are most commonly installed near each piece of switchgear that supplies a reactive load.

Engineering Toolbox.

Trane has a program called Engineering Toolbox, available online or throughTrane Desktop Manager, that can be used to calculate the kilovolt-amperes reactive (kVAR) of correction needed. Toolbox can calculate kVAR using information from the motor data sheets without adjustments at 60 and 50 Hz. Contact yourTrane sales representative for more information.

PFCC Application Guidelines.

Three “rules” govern the application of capacitors dedicated to a specific reactive load and its switchgear:

• “Rule 1”—Simultaneously disconnect capacitors and load from line power

• “Rule 2”—Size motor overload protection to account for capacitor-supplied current

• “Rule 3”—Accurately size PFCCs that remain connected to the motor when it is offline

These guidelines are explained on the following pages.

Rule 1— Simultaneously disconnect capacitors and load from line power.

If the capacitors are not switched offline when the load is disconnected, they continue to add capacitance to the electrical distribution system. A “leading” power factor—too much capacitance may eventually develop. This overcorrection causes poor voltage regulation, i.e., voltage is high when the circuit is unloaded, then drops as loads are added.

Rule 2— Size motor overload protection to account for capacitor-supplied current.

Overloads are typically set to measure the total current drawn by the motor.When PFCCs are used, they become another source for a part of that current. If the current they provide is not “seen” by the overload protectors, potentially damaging amperage can reach the motor. The simplest way to ensure that the overloads “see” all current supplied to the motor is to position the PFCCs upstream of the overloads as shown in Figure 49 .

CTV-PRB004-EN

CTV-PRB004.book Page 71 Sunday, December 18, 2011 6:39 PM

Starter Options

Figure 49. PFCCs installed downstream of starter contactor, upstream of overloads

Power

Circuit

1

2

3

Motor Starter

Contactor

Overload

Protectors

Motor

Fusible

Safety Switch or

Suitable Breaker

Enclosed

Capacitor Unit

3-Phase

Capacitor

Fuses

If the capacitor connection points are downstream of the overload devices, route the PFCC leads through the overloads as shown in Figure 50, p. 71 .This assures that the overloads register both line- and capacitor-supplied current.

Figure 50. PFCC wires routed through overload protectors

1

2

3

Power

Circuit

Fusible

Safety Switch or

Suitable Breaker Overload

Protectors

Motor

Starter

Contactor

Enclosed

Capacitor Unit

Fuses

3-Phase

Capacitor

Motor

Rule 3— Accurately size PFCCs that remain connected to the motor when it is offline.

Connecting PFCCs to the load side of the motor-starter contactor is commonly used as a simple, low-cost way to comply with “Rule 1.” However, the motor may be damaged if the PFCCs are too large. As a “rule of thumb,” the maximum corrected power factor is 95 percent for a CenTraVac chiller motor operating at full load.

Failure to comply with this rule can cause significant damage due to voltage regeneration. The manufacturers of CenTraVac chiller motors place maximum limits on both the corrected power factor and the capacitor size. PFCCs that remain connected to the motor when it is offline must not exceed the motor manufacturer’s maximum limit.

CTV-PRB004-EN 71

CTV-PRB004.book Page 72 Sunday, December 18, 2011 6:39 PM

Starter Options

Figure 51. PFCCs with separately controlled motor contactor

1

2

3

Power

Circuit

Fusible

Safety Switch or

Suitable Breaker

Overload

Protectors

Fuses

Motor

PR Motor Starter

Contactor or

Silicon-Controlled

Rectifiers (SCRs)

C

Enclosed 3-Phase

Capacitor Unit

Line-side PFCC placement.

Figure 51 , depicts an arrangement that provides an alternative to installing capacitors downstream of the motor-starter contactor. While this configuration can be used with any type of starter, it is mandatory for all solid-state starters.

Notice that the PFCCs are connected to the line side of the main contactor (or other switching device) via a separately controlled contactor.This separate contactor is governed by a pilot relay (PR) at/in the motor-starter contactor or silicon controlled rectifiers (SCRs, solid-state starter applications) to switch the capacitors on- and offline with the load.

By connecting the PFCCs through a separate contactor they do not remain connected to the motor or the line when the motor is disconnected.This configuration prevents voltage-feedback problems and can be used for cases where correction beyond 95 percent is desirable. Correction beyond the manufacturer’s maximum limit should not be done without consulting the manufacturer regarding the application.

If the PFCC connections are downstream of the overloads, the capacitor leads must be routed through the overloads as Figure 51, p. 72 illustrates. Notice that the capacitors are not connected to the motor when it is disconnected from the line. This prevents the “motor-generated voltage buildup” described in “Rule 3”, p. 71 .

72 CTV-PRB004-EN

CTV-PRB004.book Page 73 Sunday, December 18, 2011 6:39 PM

Glossary

A

Acceleration time

The time it takes a motor to reach full design speed from the moment power is applied. Typical CenTraVac motor acceleration times associated with various starter types are listed in Table 5, p. 17 (low voltage) and Table 7, p. 31

(medium voltage).

Advanced motor protection system

Standard motor protection provided by the CenTraVac microprocessor-based control panel. By monitoring current and voltage in each of the three motor power phases, the panel provides protection throughout the motor starting and running modes from the adverse effects of phase imbalance, phase failure, phase reversal, overvoltage, undervoltage, and electrical distribution fault

(momentary power loss). Sensing any of these faults, the panel trips-out the motor instantaneously and provides a diagnostic display. The chiller controller also protects

“adaptively” for overcurrent. By reducing the load, it may be able to avoid a shutting down the chiller once it reaches the current limit.

Automatic restart is provided after restoration of power when the stoppage is caused by distribution fault or extended power loss.

Air break

Contacts exposed to open air that rely on an air gap to keep an electrical circuit open. Air break contactors are an obsolete technology that has been replaced by vacuum break contactors. See “Vacuum break,” p. 81 .

Aluminum conductors

Trane requires that power wiring to the motor use copper conductors. Aluminum conductors are not suitable for the following reasons:

•UL requirements

•Galvanic corrosion

•Higher probability of connection failure

•Terminal block design

Galvanic corrosion occurs when air and moisture are present at an aluminum-copper connection. The resulting electrolysis process causes the loss of aluminum at the interface of the dissimilar metals.

Another reason to use copper conductors is the decreased probability of connection failure . Aluminum connections require greater care at initial installation as well as periodic maintenance and inspection because of oxidation, torque requirements, cold flow, and thermal expansion coefficients .

Greater care in connecting aluminum wire is required since an aluminum oxide film must be removed or penetrated before a reliable aluminum joint can be made.

This oxide film insulates the aluminum and increases joint resistance.

Torque requirements are critical when aluminum connections are made. It is difficult to ensure that these requirements will be met at the time of installation.

Cold flow or “creep” results because aluminum has a lower modulus of elasticity than copper and tends to creep away from a stressed area when under pressure.

The resulting loosened connection can increase joint resistance and lead to failure of the connection. Periodic maintenance and inspection is required to assure good connections.

Aluminum and copper have different thermal expansion coefficients . Aluminum expands 36 percent more than copper under thermal cycling. When the terminals and connections are subjected to a large temperature change, a gap may open between the aluminum cable and the copper lug. This, combined with cold flow, can result in a very high resistance joint and lead to failure of the connection.

The final reason to use copper conductors is terminal block design . Because aluminum electrical conductivity is about 60 percent that of copper, larger aluminum cables are required to conduct the same amount of current.

These larger cable sizes may not fit terminals designed for copper. It is also possible that the block itself may not be suitable for use with aluminum wire as determined by the block manufacturer.

Amps, motor full-load amps (FLA)

FLA is the amperage the motor would draw if it was loaded to its full rated capacity, i.e. motor size kW. The

FLA is not available from the selection program; however, it can be obtained from CenTraVac Field Sales Support.

Amps, motor locked-rotor amps (LRA)

Once a motor has been selected, there is a specific locked rotor amperage value associated with the specific motor.

This is the current draw that would occur if a motor was running, and then the rotor shaft was instantaneously held stationary. LRA is typically 6–8 times that of the motor fullload amps (FLA). LRA is also used commonly in discussing different starter types and the amperages associated with the start.

CTV-PRB004-EN 73

CTV-PRB004.book Page 74 Sunday, December 18, 2011 6:39 PM

Glossary

Amps, primary rated-load amps (RLA)

Commonly referred to as the selection RLA or the unit

RLA. This is the amperage that is drawn when the chiller is at full cooling capacity in terms of cooling tons (kW).

RLA is listed on the nameplate, and it is the key number used to size the starter, disconnects, circuit breakers, and

Adaptive Frequency Drives (AFD) for a typical chiller. It is also the value used to determine the minimum circuit ampacity (MCA) for sizing conductors. Primary RLA is always less than or equal to the motor full-load amps

(FLA).

Anti-recycle protection

A control method that limits the number of compressor starts within a given time period. Prior to 2000, the

CenTraVac was limited to one start every 30 minutes

(30 minutes from start-to-start).

Today, a more flexible protection system called restart inhibit is utilized. Typically several rapid restarts are allowed before a time limit is set. The time limit, if enforced due to several rapid restarts, is dependent on motor winding temperature, unit size, and an adjustable delay time constant.

This protection is a standard feature of the CenTraVac control panel.

Available fault current (AFC)

Electrical engineers usually calculate and design to a potential short-circuit current that originally comes from the utility power system. They call this term the available fault current because they take the potential fault current and then evaluate it via computer programs to determine an available fault current just upstream of the chiller starter or frequency drive. The starter short-circuit current rating should be greater than or equal to the available fault current to safely contain starter components should a short-circuit occur.

B

Bus

A bar of conductive material—usually copper—used to carry large electrical currents to supply multiple circuits or components. A bus is typically used to connect several medium-voltage starters together and thereby require only a single power connection for incoming line power.

C

California code

Available on CenTraVac chillers with low-voltage starters

(UL as standard) with disconnects or circuit breakers. Lowvoltage starters with terminal blocks require a special configuration which is available as a standard option in the order system. On medium voltage, the standard UL certification satisfies California Code requirements.

Circuit breaker

A device that protects a circuit by opening its contacts when a current responsive element senses overcurrent or short-circuit current. A circuit breaker protects electrical components from further damage if any one component within that system experiences a short circuit. Circuit breakers are used on low-voltage starters only. The overload function is not used; overload is accomplished by the chiller controller. Circuit breakers are sized based on the primary RLA from the nameplate, the required AIC of the breaker, and the required SCCR of the starter enclosure.

Contactor

A multi-pole relay whose contacts are rated to carry line current. The contactor connects and disconnects a motor to and from line power. The coil of a contactor may be operated by line voltage, control voltage, or through a rectifier (DC voltage).

Control-power transformer (CPT)

A device that reduces incoming line voltage to control voltage (i.e., 480 V to 120 V). The control-power transformer is usually located in the starter. A 4 kVA transformer is provided as standard in CenTraVac starters—3 kVA transformer provided with AFDs. The

Enhanced Electrical Protection Package provides an option to mount the CPT separately on the side of the chiller. This transformer takes care of the chiller’s auxiliary power needs such as the purge, oil pump, heater, etc.

Corona

A visible pale glow surrounding an insulated conductor typically carrying over 2000 volts. Ozone odor is present and the air around the wire becomes ionized. An increase in voltage may cause the corona effect of adjacent wires to increase until spark-over occurs. See “Stress cone

(stress relief cone),” p. 80 .

Current-limiting fuse

A current-limiting fuse is a fuse that recognizes the rate of current increase and will melt its element and open the circuit in less than one-quarter of an electrical cycle in the event of a short circuit. Thus, the total short-circuit current available never passes through the current-limiting fuse.

CenTraVac medium-voltage starters contain three currentlimiting fuses as standard.

74 CTV-PRB004-EN

CTV-PRB004.book Page 75 Sunday, December 18, 2011 6:39 PM

Glossary

Current transformer

A device that produces a reduced current signal that is proportional to the primary current. A current transformer may resemble a square or round doughnut. Each motor lead passes through the center of a current transformer and a reduced proportional current signal is obtained at the current transformer leads. There is no direct electrical connection between the motor lead and the current transformer. The voltage in the output circuit of a current transformer will be whatever voltage is necessary to drive the output current through the load with the voltage limited only by the line power or saturation level of the current transformer; therefore, the secondary of a current transformer must never see an open circuit.

D

Differential motor protection

Means of detecting current leakage in a motor from winding-to-winding or from winding-to-ground. Differential motor protection requires a six lead motor. Three current transformers, one for each motor phase, monitor the current in and out of each of the motor windings. If, due to leakage or some fault within the motor, the current in and the current out are not identical in each winding, a current will be induced in the secondary of one or more of the current transformers. This induced current will energize a differential relay which will open a contactor and deenergize the motor.

Differential protection is available as part of the Enhanced

Electrical Protection Package’s supplemental motor protection option. Differential protection is not applicable to Trane’s standard, low-voltage wye-delta starters.

Differential relay

Current sensitive relay that has three coils, each connected to one of the current transformers used for differential protection. Energizing any one of the three coils will operate the relay. A differential relay is furnished with the differential protection option.

Disconnect

A device for manually isolating an electrical circuit.

Distribution fault

Transient power losses longer than 2 or 3 cycles will be detected and cause the chiller to shut down, typically within 6 cycles. The chiller can also shut down due to excessive or rapid voltage sags. Shutting down the chiller prevents the motor having power reapplied with different phasing. Utility power outages are not considered distribution faults—Trane refers to this type of fault as a momentary power loss (MPL).

E

Enclosure

The sheet metal structure and access door that surrounds the starter. The standard enclosure is NEMA Type 1, which means general purpose indoor with a gasketed access door. Other enclosure classifications to meet requirements of different environments are available as special options. See “NEMA 1,” p. 78 .

F

Full-load amps (FLA)

See “Amps, motor full-load amps (FLA)”, p. 73 .

Fuse

A device that protects a circuit by fusing (melting) open its current-responsive element due to an overcurrent or short-circuit current. A fuse protects electrical components from further damage if any one component within that system experiences a short circuit.

Fuse - dual element

A dual element fuse is a single cartridge fuse having two different current-responsive elements in series. A dual element fuse is required to carry 500 percent of its current rating for a minimum of 10 seconds. One of the current-responsive elements will have inverse time characteristics while the other element will handle larger currents without intentional time delay. Since most

CenTraVacs draw inrush currents in excess of this rated minimum ampacity during acceleration, all low-voltage

CenTraVacs with fuse protection must use dual element fuses.

Fuse rating

NEC code allows a maximum fuse rating that is

175 percent of the RLA. To prevent blowing fuses during motor acceleration this maximum value is allowed to increase up to 225 percent of the RLA. CenTraVac dual element fuses are sized at 150–195 percent of the chiller

RLA.

G

Ground fault

A leakage of line current to ground. Ground faults are typically caused by the breakdown or cracking of wire insulation.

CTV-PRB004-EN 75

CTV-PRB004.book Page 76 Sunday, December 18, 2011 6:39 PM

Glossary

Ground fault protection—low voltage

Low voltage ground fault protection consists of a ground fault sensor, a ground fault relay, and a disconnect device

(circuit breaker or non-fused disconnect switch) equipped with a shunt trip device.

The ground fault sensor is a specially rated current transformer and must be applied only with a ground fault relay. Ground fault sensors cannot be used with any other equipment.

The ground fault relay is designed to work with a ground fault sensor. The current level required to activate the ground fault relay is adjustable. The response speed (time delay) is also adjustable to avoid nuisance trips. All ground fault relays require a manual reset. The time-current tripping curve of a ground fault relay is nearly instantaneous when the current setting and time delay have been exceeded. The contacts of the ground fault relay energize a shunt trip device to open the circuit and isolate the ground.

The shunt trip device is a circuit breaker with a shunt trip coil. Such a circuit breaker can either be opened manually, opened by its current sensing element (short circuit), or opened by energizing its shunt trip coil. A circuit breaker is used to open the circuit because it is capable of successfully interrupting fault current; the current to ground may be catastrophic.

The minimum setting of the ground fault protection system should be 20 percent of the disconnect rating with a 10-cycle time delay.

Ground fault protection—medium voltage

Medium voltage ground fault protection consists of a ground fault sensor and ground fault relay. The ground fault relay interrupts control power to the main contactors causing them to open. All medium-voltage starters are equipped with current-limiting fuses. In the event of a catastrophic ground, the current-limiting fuses would react much faster than the ground fault protection relay; therefore, the fuses would perform the act of interrupting the circuit and isolating the ground.

The minimum setting of the ground fault protection system should be 20 percent of the disconnect rating with a 10-cycle time delay.

Grounding

Electrical refrigeration components such as motors and control panels must be grounded for the protection of maintenance and service personnel.

Equipment ground connection bolts are provided in the control panel, the motor junction box, and in the starter of all CenTraVacs. On those CenTraVacs where the control panel is isolated, grounding straps are installed to ground the control panel to the chiller frame. Thus, all pieces of a

CenTraVac are provided with an individual equipment ground.

It is the responsibility of the installing contractor to ground the CenTraVac equipment to an earth ground per NEC and local codes.

“Gutless” circuit breaker

See “Non-fused disconnect”, p. 78 .

I

Inrush current

The current drawn by a motor during acceleration. Inrush current for various types of starters (in percent of LRA) is given in Figure 6, p. 18 (low voltage) and Figure 22, p. 31

(medium voltage).

Interlock, electrical

Auxiliary contacts on a contactor, typically used in control voltage circuits, to monitor the position of the contactor.

These auxiliary contacts may be normally open, normally closed, or convertible.

Interlock, mechanical

Bars, levers, or catches that physically prevent operation of a device under certain circumstances. (i.e. a CenTraVac starter door may not be opened if a circuit breaker is closed)

Interrupting capacity

The rated maximum current that a device can successfully interrupt without damage to itself. This applies to a circuit breaker or a fuse only. It is not proper to refer to a starter as having an interrupting capacity. Starters have an overall short-circuit current rating. See “Short-circuit current rating (SCCR)”, p. 79 .

Ionization

Insulated conductors carrying over 2000 volts are subject to ionization. Ionization results in the formation of gas pockets between the insulation layers. These gas pockets form areas of unequal stress that may lead to premature breakdown of the insulation. See “Stress cone (stress relief cone)”, p. 80 .

IQ digital meters

This is a starter mounted meter that digitally displays many parameters. It is a starter option, however most

76 CTV-PRB004-EN

CTV-PRB004.book Page 77 Sunday, December 18, 2011 6:39 PM

Glossary functions are displayed as standard on the unit controller.

See the comparison tables ( Table 2, p. 13 and Table 3, p. 14 ).

Isolation switch

A device used to connect and disconnect a load to and from line power for servicing. Isolation switches are nonload break and cannot be opened under load. Trane

® medium-voltage starters have a mechanical interlock that prevents the isolation switch from being opened while the chiller is running. This is a standard item on Trane

® medium-voltage starters.

K

Kirk key

A locking arrangement between a remote disconnect switch and a starter that is designed to prevent closing the remote switch and powering the starter that is being serviced.

A single key is used and it is held captive in the disconnect switch. The disconnect switch must be opened and then locked open. The kirk key may then be removed and used to unlock the starter. The key remains captive in the starter until the starter door is closed and locked. The key may then be removed and used to unlock the disconnect switch. The switch may then be closed.

L

Lightning arrester

A device that protects electrical equipment from high voltage spikes by providing a high resistance path (an air gap) to ground—essentially an air gap small enough to allow a spark-over to occur for voltages much larger than the chiller’s operating voltage. The device provides protection by consistently conducting to ground when the magnitude of the voltage exceeds a predetermined value.

Although lightning arresters may be used alone, they are used usually in conjunction with surge protection capacitors.

The function of a lightning arrester is to limit the magnitude of a voltage spike. The function of a surge capacitor is to limit the rate of rise of a voltage spike. See

“Surge capacitor,” p. 80 .

Lightning arresters are a starter option.

Load-break switch (LBS)

A manual switch that has an interrupting rating and can be used to safely interrupt a live circuit. It is sometimes called an ADM switch. This term is typically used with mediumvoltage starters when customers want Trane to provide a load-break switch. The standard isolation switch that comes with medium-voltage starters is non-load break.

The load-break switch is a design special. The switch is housed within a 90" high, 36" wide, and 30" deep enclosure. A circuit breaker or non-fused disconnect on low-voltage starters can be used as a load-break switch.

Locked-rotor amps (LRA)

See “Amps, motor locked-rotor amps (LRA)”, p. 73 .

Lug

A device used to mechanically connect a conductor (wire) to a piece of electrical equipment. Lugs are furnished by the starter vendor. The number of wires per phase and range of wire sizes that the lugs will accept are listed in the starter submittals. The range of wire sizes indicates the maximum size wire that will fit into the lug hole and the minimum wire size that the screw can securely clamp in place. Optional lugs that accommodate different number of wires per phase and size are generally available for every starter. These can be purchased through a local vendor if required.

Note:Wire sizes “pulled” by contractor that are different from the lug sizes shown on the starter submittal will impact the lug sizes needed. In this case, the correct lug sizes must be obtained locally.

M

Maximum overcurrent protection (MOP)

The maximum overcurrent protection (MOP, or sometimes abbreviated as MOCP) appears on the chiller nameplate.

The electrical engineer often wants to know the MOP when selections are being made. It is used to assist in the sizing of fuses and circuit breakers. MOP is an output of the TOPSS selection program. Also see the discussion on fuse and circuit breaker sizing ( “Electrical System—

Ratings,” p. 49 and “Electrical System—Design

Guidelines,” p. 52 ). Use of improperly sized circuit breakers can result in nuisance trips during the starting of the chiller. For CenTraVac chillers the MOP is NOT the value used to size incoming wire (see MCA).

Minimum circuit ampacity (MCA)

This term appears on the chiller nameplate and is used by electrical engineers to determine the size and number of conductors bringing power to the starter. The formula for

MCA is 1.25 x (Primary RLA) + (4000/motor voltage), rounded up to the next whole number. The formula is

125 percent of the motor design RLA plus 100 percent of the amperage of other loads (control-power transformer,

CTV-PRB004-EN 77

CTV-PRB004.book Page 78 Sunday, December 18, 2011 6:39 PM

Glossary oil pump motor, and purge etc.) MCA is an output of the

TOPSS selection program.

Table 11, p. 58 through

Table 16, p. 60 show power wire sizing based on the

MCA.

Molded case switch

See “Non-fused disconnect”, p. 78 .

Momentary power loss (MPL)

See “Distribution fault”, p. 75 .

Motor FLA

See “Amps, motor full-load amps (FLA)”, p. 73 .

Motor LRA

See “Amps, motor locked-rotor amps (LRA)”, p. 73 .

Motor size in kilowatts (kW)

The motor size is listed on the program output in kW. This is the motor’s full, rated capacity. There is an amperage draw associated with power draw at full capacity called full-load amps (FLA). FLA is the amperage the motor would draw if it is loaded to its full rated capacity i.e.

motor size kW. The FLA is not available from the TOPSS selection program, however can be obtained from

CenTraVac Field Sales Support.

Usually the selection RLA and kW are used as the nameplate RLA and kW. Occasionally, an engineer may decide to specify slightly higher RLA as the nameplate data to provide “extra” capability for the chiller. The higher kW and RLA cannot exceed the motor size (kW), the starter size (RLA), or the disconnect/circuit breaker size

(RLA).

N

NEMA 1

Enclosures are intended for indoor use primarily to provide a degree of protection against limited amounts of falling dirt.

NEMA 12

Enclosures are intended for indoor use primarily to provide a degree of protection against circulating dust, falling dirt, and dripping non-corrosive liquids.

NEMA 3R

Enclosures are intended for outdoor use primarily to provide a degree of protection against rain, sleet, and damage from external ice formation.

NEMA 4

Enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, hose-directed water, and damage from external ice formation.

NEMA 4X

Enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, hose-directed water, and damage from external ice formation.

Non-fused disconnect

A circuit breaker without a thermal or magnetic overcurrent element. It is used solely as a manual disconnect means. This is also called a “gutless” circuit breaker or molded case switch.

O

Overload protection

A scheme or device that monitors motor current and interrupts control power to the main contactor(s), disconnecting the motor from the line, if motor current exceeds preset limits of current and time. Motor current may be monitored directly or through current transformers.

Overload relay

A device that senses current flow to a motor. The relay can be set to trip at a certain value. If the motor attempts to draw current in excess of this value, the relay will trip, de-energizing the contactor coil, disconnecting the motor from the line.

P

Phase failure

An opening in one of the three main power leads caused by a blown fuse or broken conductor. This results in only one phase being delivered to the load. Thus, phase failure is the same as single phasing. Phase failure protection is standard on CenTraVac chillers with microprocessor-based chiller control panels and was available as a starter option on older CenTraVacs.

Phase imbalance

An imbalance in the current level or voltage level among the three phases. Phase imbalance can cause motor overheating.

Phase reversal

A change in the desired electrical phase relationship.

Phase reversal causes motors to rotate in the wrong direction.

78 CTV-PRB004-EN

CTV-PRB004.book Page 79 Sunday, December 18, 2011 6:39 PM

Glossary

Phase failure/phase reversal relay

A device that monitors the phase relationship and opens a contact to stop the compressor motor in the event of phase failure, phase reversal or phase imbalance.

The advanced motor protection provided by the chiller controller performs the functions of a phase failure/phase reversal relay.

Pilot relay

A term describing the fact that all CenTraVac starters start and stop the compressor by means of a relay that responds to commands from the CenTraVac control panel.

Push-to-start push-buttons or any other forms of manual starting of the compressor are not allowed. The CenTraVac safeties in the control panel must not be bypassed.

Power factor

The ratio of real power (watts) to apparent power (voltamperes). Induction motors, such as CenTraVac compressor motors, require some energy for magnetizing that does no actual work and is not registered on a wattmeter.

Power factor correction capacitor (PFCC)

May be used to improve the power factor of a CenTraVac by furnishing some of the wattless magnetizing energy required by the motor.

Power factor correction capacitors are a starter option.

They are mounted in or on the starter and are typically wired to the load side of the compressor contactor. Since the capacitors are wired in parallel with the motor, the maximum capacitor size is determined by the motor.

The capacitors furnished as a starter option will correct the compressor motor to approximately 93.5 to

95.5 percent power factor at full load.

Power wiring

Refer to Table 11, p. 58 through Table 16, p. 60 for wire sizing for line and load wire associated with CenTraVac starters.

Primary power

The performance number called primary power is the kW usage at chillers full cooling capacity. The primary power will always be less than the motor size. See “Motor size in kilowatts (kW)”, p. 78 .

Primary RLA

See “Amps, primary rated-load amps (RLA)”, p. 74 .

R

Rated-load amps or running-load amps (RLA)

See “Amps, primary rated-load amps (RLA)”, p. 74 .

Relay

An electrically-operated device whose contacts switch electrical circuits. A relay is always used as a switching device within a control circuit.

Resistance temperature detector (RTD)

A device whose electrical resistance varies with its temperature. RTDs may be used to monitor motor winding temperature.

Every CenTraVac motor has three RTDs buried within its stator windings. These RTDs are connected to the

CenTraVac control panel. There, a device monitors the resistance (hence, the temperature) of the RTDs and will stop the compressor if the motor winding temperature exceeds a preset level. These are dedicated RTDs and cannot be used for any additional functions.

If motor winding RTDs are required for any other function, the RTDs required must be described and ordered as a design special. Then, a specially built motor will be provided.

S

Short circuit

An unintentional direct electrical connection from phaseto-phase or from phase to ground resulting in low resistance and very high current flow. Short circuits can result in destruction of conductors and components. Short circuits are caused by the breakdown of insulation, poor wiring, or a conductive piece of metal that accidentally comes in contact with multiple phases or between a phase and ground (i.e. tools and service equipment). See

“Available fault current (AFC)”, p. 74 .

Short-circuit current rating (SCCR)

When a short circuit occurs, there is a period of time that the short-circuit current passes to the shorted circuit before the protection device (circuit breaker or fuse) can open. This time can be as long as 0.020 seconds (1 cycle).

The short-circuit current rating of a starter is the maximum short-circuit current that it can pass safely. Components within the starter may be destroyed, but the starter cabinet will safely contain any sparks or flying debris. UL listed starters have a listed short-circuit current rating.

Short-circuit withstand rating (SCWR)

See “Short-circuit current rating (SCCR),” p. 79 .

CTV-PRB004-EN 79

CTV-PRB004.book Page 80 Sunday, December 18, 2011 6:39 PM

Glossary

Shunt trip

A tripping coil added to a circuit breaker or non-fused disconnect to provide a means of tripping the circuit breaker with an external signal. See “Ground fault protection–low voltage”, p. 76 .

Silicone controlled rectifier (SCR)

A solid state signal controlled, one-way power switching device commonly used in solid-state starters and variablefrequency drives.

Single phase (single phasing)

See “Phase failure”, p. 78 .

Solid-state starter

A starter that starts and accelerates a motor at a preset acceleration rate and current limit. A solid state starter performs this function by modulating the current/voltage wave form delivered to the motor with silicon controlled rectifiers (SCRs). For more information on this starter type, refer to CTV-SLB017-EN ( Solid-State Starters for

Trane Chillers ).

Starter

A device consisting of both a contactor and an overload protection system or device whose purpose is to start and stop a motor and protect the motor from overcurrent.

Variable-frequency drives are also classified as starters.

Stress cone (stress relief cone)

Cables carrying above 2000 volts must have a metallic shield unless the cable is specifically listed or approved for non-shielded use. Shielding is necessary because of the danger of corona or ionization. The purpose of shielding a cable is to confine its dielectric field to the inside of the cable or conductor insulation. The shielding must be grounded at one end.

Stress cones are used to reduce and control longitudinal and radial electrical stresses at the cable end to values within safe working limits for the material used to makeup the termination. An oversized junction box at the motor may be required to accommodate stress cones.

Surge capacitor

A device that protects electrical equipment from high voltage spikes by absorbing the peak energy of the spike and then releasing it into the tail of the spike.

Although surge capacitors may be used alone, they are usually used in conjunction with lightning arresters. See

“Lightning arrester”, p. 77 .

Surge capacitors are a starter option.

Switchgear

A switchgear type starter is an across-the-line low-voltage starter that uses a circuit breaker to connect and disconnect the compressor motor to and from the line.

Usually a separate power source (i.e., 125 Vdc from a battery bank) is used to open and close the circuit breaker on demand.

Switchgear starters should be used with caution. Some switchgear starters contain a relay that will trip the circuit breaker if auxiliary power is lost. Others do not contain this auxiliary power monitoring relay. It may then be impossible to automatically disconnect the compressor motor from the line in case of a compressor, chiller or starter fault, if auxiliary power is lost while the compressor is running.

T

Top hat

A supplementary sheet-metal enclosure provided with unit-mounted medium-voltage starters and SMP cabinets to help accommodate the space requirements of stress cones.

Transducer

A device that converts a control signal from one form to another. For example, conversion of a 0–20 psig pneumatic control signal to a 4–20 milliampere electrical control signal.

Transition

Transition is the action taken by a starter when changing from one configuration to another, such as changing

(transitioning) from the wye/star configuration to the delta configuration.

Open transition … a term indicating that the motor is disconnected from the line, transition is performed and then the motor is reconnected to the line.

Closed transition … a term indicating that the motor remains connected to the line during transition.

All CenTraVac starters are closed transition. All SBO starters must be closed transition.

Open transition starters cause stresses in the motor windings that shorten motor life.

Inrush current is nearly constant during acceleration and then drops quickly to less than RLA when the motor reaches full speed. Starters using the Trane

® microprocessor controller monitor motor current continuously and initiate transition when the motor current drops below 85 percent of RLA.

80 CTV-PRB004-EN

CTV-PRB004.book Page 81 Sunday, December 18, 2011 6:39 PM

Glossary

Trip unit

Device that opens the operating mechanism within the circuit breaker in the event of a prolonged overload or short-circuit current. To accomplish this, an internal electronic rating plug is provided, which tells the trip unit when to open the mechanism. Rating plugs are factory set within specific ranges to meet motor performance requirements and are field-adjustable.

U

Unit controller

The microprocessor controller mounted on the chiller. Also referred to as the control panel.

Vacuum break

Contacts that are encapsulated in an evacuated, ceramic bottle. Since the contacts operate in a vacuum, arcs are quickly extinguished because there are no ionized gases present to support conduction. The claimed advantages are no contact maintenance, long contact life and safety, since there is no exposed arcing. All medium- voltage starters used by Trane have vacuum break contactors.

Vacuum break contactors are used typically only on medium-voltage starters.

V

Voltage

The following voltages apply to CenTraVacs:

Control Voltage

Low Voltage

120 Vac

208–600 Vac

Medium Voltage 601–13,800 Vac

The electrical power industry refers to 2,000 through

69,000 volts as medium voltage.

Voltage monitoring relays, overvoltage relay

A relay and an adjustable line voltage monitor that will stop the chiller if the line voltage exceeds a preset value.

This overvoltage monitoring system is a lock-out type that requires manual reset at the starter.

The chiller controller provides under/overvoltage protection as standard.

Voltage monitoring relays, undervoltage relay

A nonadjustable relay that is powered directly by line voltage. If line voltage drops below 55 percent nominal voltage, the undervoltage relay will stop the chiller. This relay requires a manual reset at the starter.

The chiller controller provides under/overvoltage protection as standard.

Voltage monitoring relays, adjustable undervoltage relay

A relay and an adjustable line voltage monitor that will stop a chiller if line voltage drops below a preset value.

This undervoltage monitoring system is a lock-out system that requires manual reset at the starter.

The chiller controller provides under/overvoltage protection as standard.

W

Wattmeter

A device that displays instantaneous power (watts) in the form of a dial meter or a digital display. When a wattmeter is ordered for a starter, the wattmeter option includes all necessary transformers.

Watt-hour demand register

An option on a watt-hour meter that indicates the total power used per time period (i.e., 15 minutes). The value displayed is proportional to the electrical energy used in the unit's time period. The watt-hour demand value will only increase when the power demand in a new time period exceeds the power demand in any previous time period; thus, the demand register indicates the largest power demand in any time period. The demand register may be manually reset to zero to monitor a new series of time periods.

Watt-hour meter

A device that measures and registers the cumulative amount of electrical energy used in terms of watt-hours

(or kilowatt-hours). This is a standard feature on the unit control panel.

When a watt-hour meter is ordered for a starter, this option includes all necessary transformers.

Watt-hour meter pulse initiator

A device that generates pulses (contact closures) proportional to a definite energy value (watt-hours per pulse). Output contacts of pulse initiators are normally connected to pulse-operated demand recorders or used to feed energy consumption information to computers and load controllers.

When ordering pulse initiators, the type of pulses and the pulse rate the end devices will accept must be indicated.

Withstand rating

See “Short-circuit current rating (SCCR)”, p. 79 .

CTV-PRB004-EN 81

CTV-PRB004_NewestBackCover.fm Page 82 Monday, December 19, 2011 8:41 AM

Trane optimizes the performance of homes and buildings around the world. A business of Ingersoll Rand, the leader in creating and sustaining safe, comfortable and energy efficient environments, Trane offers a broad portfolio of advanced controls and HVAC systems, comprehensive building services, and parts.

For more information, visit www.Trane.com.

Trane has a policy of continuous product and product data improvement and reserves the right to change design and specifications without notice.

© 2011 Trane All rights reserved

CTV-PRB004-EN 19 Dec 2011

Supersedes CTV-PRB004-EN (17 Sep 2010)

We are committed to using environmentally conscious print practices that reduce waste.