TECHNICAL BULLETIN TB-6515 Zero Volt Monitor
Installation, Operation and Maintenance
Made in the
United States of America
strap properly, the monitor measures the loop resistance
consisting of one wire of the ground cord, one-half of
the wristband, the person’s skin, the second half of the
wristband, and a second wire in the ground cord. If any
part of the loop should open (become disconnected or
have out of limit resistance), the circuit will go into alarm
state” nonetheless, due to the redundancy inherent
in the dual-wire wrist strap design, the operator will
continue to be grounded via the second intact wire.
The Zero Volt Monitor is available in the following
models:
Figure 1. EMIT Zero Volt Monitor
Description
The EMIT Zero Volt Monitor using ZERO VOLT
MONITORING™ resistive loop technology meets ANSI/
ESD S20.20 conitinuous monitoring requirements,
continuously verifies the proper resistance to ground
of the operator and worksurface [or other item at the
workstation] and will detect charge accumulation on the
operator. It is to be used with dual-wire wrist straps (not
included). Zero Volt Monitoring sends two test signals
which are of equal and opposite polarity. The result
is near zero voltage being placed on the operator with
respect to equipment ground. The Zero Volt Monitor is
also unaffected by capacitance variations associated
with personnel and environmental conditions. Dual-Wire
Continuous Monitors provide redundancy; even if one
dual-wire wrist strap conductor is severed, operator has
reliable path-to-ground with other wire. The steady state
DC test signal will detect intermittent failures that may
be missed by pulsed DC systems. An EMIT Calibration
Unit is available so proper compliance verification per
ESD TR53 can be performed at the workbench without
taking the monitor out of service. Each Zero Volt Monitor
is calibrated within accepted procedures and standards
traceable to the National Institute of Standards and
Technology (NIST) and includes a NIST certificate.
Item
Power Adapter Wrist Strap Kit
50528 N. America
19690
50537 None
19690
50538 N. America
09163
Packaging
1
1
1
2
2
2
1
2
Zero Volt Monitor
Snap Kit
Power Adapter (50528, 50538 only)
Wrist Strap Kits
Operator Cables (black and white)
Mat Cords (black and white)
Monitor Ground Cord (green)
Mat Ground Cords (green)
Features and Components
A B
C
Per ANSI/ESD S1.1 section 6.1.3 Frequency of
Functional Testing “The wrist strap system should be
tested daily to ensure proper electrical value. Daily
testing may be omitted if constant monitoring is used.”
Per ESD Handbook ESD TR20.20 section 5.3.2.4.4
“Typical Test programs recommend that wrist straps that
are used daily should be tested daily. However, if the
products that are being produced are of such value that
knowledge of a continuous, reliable ground is needed,
and then continuous monitoring should be considered or
even required.”
Per ESD Handbook ESD TR20.20 section 5.3.9.2.2
Dual Conductor Resistance Continuous Monitors “This
type of monitor is used with a two wire (dual conductor)
wrist strap. The wrist strap assembly consists of a
two-wire ground cord and a wristband that has two
isolated halves. When a person is wearing the wrist
H
D
F
G
I
J
E
FRONT VIEW
K
LMN
O
P
BACK VIEW
Figure 2. Zero Volt Monitor features and components
EMIT - 3651 Walnut Avenue, Chino, CA 91710 • (909) 664-9980 • Website: DescoEMIT.com
TB-6515 Page 1 of 6
October 2017
© 2017 DESCO INDUSTRIES, INC.
Employee Owned
A.Operator Fail Low LED: Illuminates and alarm sounds
when the operator’s resistance is below the test limit.
B.Operator Pass LED: Illuminates when the operator is
properly grounded.
C.Operator Fail High LED: Illuminates and alarm sounds
when the operator’s resistance is above the test limit.
D.Operator Standby LED: Illuminates when the operator is
not connected to the remote.
E.Operator Charge LED: Illuminates and alarm sounds
when the charge on the operator is greater than ±1.25V.
F. Mat Fail LED: Illuminates and alarm sounds when the
worksurface mat is not properly grounded.
G.Mat Fail LED: Illuminates when the worksurface mat is
properly grounded.
H.Alarm Audible Adjustment: Turn the trimpot clockwise to
increase the audible alarm volume and counter-clockwise to
decrease it.
I. Data Output: To be used with the EMIT Smart Hub.
J. Power Jack: Connect a 9-15VDC power adapter here.
K.Operator 2 Remote Jack: Connect the black operator
remote cable here.
L. Mat 2 Terminal: Monitors worksurface mat #2. Connect
the black mat cord here.
M.Monitor Ground Terminal: Common ground point for the
monitor. Connect the black monitor ground cord here
N.Mat 1 Terminal: Monitors worksurface mat #1. Connect
the white mat cord here.
O.Operator 1 Remote Jack: Connect the white operator
remote cable here.
P.Analog Output: Used for troubleshooting purposes by the
manufacturer.
Installation
1. Determine the mounting location of the Zero Volt
Monitor. The front panel should be visible to both
operators.
2. Determine the mounting locations of the operator
remotes. Be sure to install the remotes at a distance
that enables its leads to reach the back of the monitor.
NOTE: The operator remotes for the Zero Volt Monitor
are configured differently from other EMIT remotes. Be
sure to only use the remotes that were packaged with
your monitor.
3. Install tinned wire ends of the mat cords to their
appropriate screw terminal block located at the back of
the monitor.
4.
Attach the worksurface mats to ground using the green
mat ground cords. Install the ring terminal end of the
cord to an appropriate ground point. Attach the snaps
terminals to the snaps on the worksurface mat.
5.
Install the tinned wire end of the black monitor ground
cord to the ground terminal located at the back of the
monitor. Install its ring terminal to an appropriate ground
point. Be sure to use a different ground point than the
one used for the mats. The face plate screw of
a grounded AC wall outlet may provide a convenient
connection point.
6.
Route the mat cords from the back of the monitor to
the snaps on worksurface mats. The white cord is for
worksurface mat #1. The black cord is for worksurface
mat #2.
7. Insert the operator remote cables into their appropriate
jacks located at the back of the monitor. The white cable
is for operator #1. The black cable is for operator #2.
8. Connect the power adapter to the power jack located
at the back of the monitor. Plug the power adapter into
a proper AC power outlet. The monitor is now powered.
EMIT - 3651 Walnut Avenue, Chino, CA 91710 • (909) 664-9980 • Website: DescoEMIT.com
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OPERATOR 2
REMOTE JACK
OPERATOR 1
REMOTE JACK
MAT 2 CORD
MONITOR
GROUND CORD
MAT 1 CORD
10mm PUSH &
CLINCH SNAPS
10mm PUSH &
CLINCH SNAPS
10mm snaps need to pierce
and clinch bottom side of mat
and be 12" - 72" apart.
10mm snaps need to pierce
and clinch bottom side of mat
and be 12" - 72" apart.
OPERATOR 2
WORKSURFACE
OPERATOR 1
WORKSURFACE
Figure 3. Installing the Zero Volt Monitor
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Employee Owned
Operation
Maintenance
1. Monitoring of the operators will remain in the STANDBY
condition until a wrist cord is plugged into the operator
remote.
2.
Plug a wrist strap cord, not attached to the wristband,
into the monitored jack labeled WRIST STRAP
MONITOR located on the remote. This automatically
activates the selected operator channel. The
corresponding operator LED should illuminate red and
the alarm should sound on the monitor.
3.
Remove the charges from your body by making contact
with a properly grounded ESD worksurface. Snap the
cord to the wristband, and fit it snugly onto your wrist.
This should silence the audible alarm and cause the
corresponding operator LED to switch from red to
green. If this does not happen, examine the wrist cord
for continuity or damage and your wrist band to ensure
that it is securely fit. If you have dry skin, apply an
approved dissipative hand lotion such as Menda
Reztore™ ESD Hand Lotion.
4.
The AUX MAT jack located on the operator remote
is a grounded and unmonitored connection for guests.
It must be used with a banana plug wrist cord and
single-wire wristband.
JUMPER SETTINGS
Feature
Enable
Disable
Audible Adjust
JP5 - OFF
JP5 - ON
Charge Display
JP6 - OFF
JP6 - ON
Data Output
JP7 - ON
JP7 - OFF
JP5
JP2
JP1
JP7
JP6
Figure 5. Jumper locations
Calibration
Figure 4. Connecting wrist straps to the operator remote
CHARGE DETECTION
The CHARGE LED illuminates and the alarm sounds when
the charge on the operator is greater than ±1.25V. To
disable charge detection on the display, shunt jumper JP6
inside the unit. If a charge is detected while using this
configuration, the display will remain in its previous state until
the charge is no longer detected.
The Zero Volt Monitor is calibrated to standards traceable
to NIST. Frequency of recalibratrion should be based on
the critical nature of those ESD sensitive items handled
and the risk of failure for the ESD protective equipment and
materials. In general, we recommend that calibration be
performed annually.
Use the EMIT 50524 Limit Comparator for Dual-Wire
Monitors to perform periodic testing (once every 6-12
months) of the Zero Volt Monitor. The Limit Comparator
can be used on the shop floor within a few minutes virtually
eliminating downtime, verifying that the monitor is operating
within tolerances.
See TB-6542 for more information.
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MAT RESISTANCE SETTINGS
3.5M
1. If the desired resistance is 3.5M, jumpers JP1 (MAT 1)
and JP2 (MAT 2) need to be on one pin (see Figure 5).
2. The respective potentiometers need to be adjusted fully
clockwise. The pots are located inside the unit on the
bottom board (see Figure 7).
HIGH RESISTANCE (10k - 3.5M)
Figure 6. EMIT 50524 Limit Comparator for Dual-Wire
Monitors
NOTE: The series “test” resistance is not the same as the
operator to ground resistance. As shown in Figure 6, the
series resistance is made up of the 1 megohm resistor in the
cord, the wristband to operator’s skin resistance (skin contact
resistance) and the operator’s resistance (human body
resistance).
1. If the desired resistance is 10k - 3.5M, jumpers JP1
(MAT 1) and JP2 (MAT 2) need to be on one pin (see
Figure 5).
2. Use a resistor decade box to set the desired resistance
between the ground terminal and ground.
3. Connect the mat wire to the decade box and connect the
decade box to ground.
4. Turn the appropriate potentiometer counter-clockwise
until the GROUND LED illuminates red and alarm
sounds (see Figure 7).
For a given series resistance, the typical operator to ground
resistance can be calculated from the following formula:
5. Slowly turn the potentiometer clockwise until the
GROUND LED illuminates green.
Roperator to ground = (Rseries + 2 megohms)
4
6. Add 10% more resistance (at least 1 ohm) to the decade
box and verify that the GROUND LED illuminates red
and alarm sounds.
For a given operator to ground resistance, the series
resistance can be calculated from the following formula:
Rseries = (Roperator to ground x 4) - 2 megohms
Skin Contact
Resistance
7.
Return back to the starting resistance and confirm that
the green LED illuminates again. Repeat steps 4-7 if the
monitor does not fail with the increased resistance or
return to a pass condition.
LOW RESISTANCE (< 1k)
1 megohm in Cord
1. If the desired resistance is < 1k, jumpers JP1
(MAT 1) and JP2 (MAT 2) need to be on both pins (see
Figure 5).
Human Body
Resistance
To Operator
Remote
2. Use a resistor decade box to set the desired resistance
between the ground terminal and ground.
3. Connect the mat wire to the decade box and connect the
decade box to ground.
4. Turn the appropriate potentiometer counter-clockwise
until the GROUND LED illuminates red and alarm
sounds (see Figure 7).
Skin Contact
Resistance
1 megohm in Cord
Figure 7. Operator series resistance
5. Slowly turn the potentiometer clockwise until the
GROUND LED illuminates green.
6. Add 10% more resistance (at least 1 ohm) to the decade
box and verify that the GROUND LED illuminates red
and alarm sounds.
7.
Return back to the starting resistance and confirm that
the green LED illuminates again. Repeat steps 4-7 if the
monitor does not fail with the increased resistance or
return to a pass condition.
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Limited Warranty, Warranty Exclusions, Limit of
Liability and RMA Request Instructions
See the EMIT Warranty http://EMIT.descoindustries.com/Warranty.aspx
MAT 2 MAT 1
Figure 8. MAT potentiometers
Specifications
Operating Voltage
100-240 VAC, 50/60 Hz
Operating Temperature
32°F - 104°F (0 - 40°C)
Monitor Dimensions 5.6" x 4.7" x 2.6"
(14.2cm x 11.9cm x 6.6cm)
Monitor Weight
1.6 lbs (0.7 kg)
TEST VOLTAGES
Operator
1.25 V
Worksurface
200 mV
TEST LIMITS
Operator
Low Fail: < 1.72 megohms
Pass: 2 - 9 megohms
High Fail: > 11.5 megohms
Worksurface
Pass: < 3.5 megohms
Fail: > 3.8 megohms
Charge Detector
Detects > ±1.25 VDC on
operator
NOTE: Worksurface must have a conductive layer such as
Dual Layer Rubber or Dissipative 3-Layer Vinyl or Micastat®
Dissipative Laminate with conductive buried layers. EMIT
Continuous Monitors are not recommended for use with
homogeneous matting.
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Employee Owned