SCS Static Monitor 790 Installation, Operation And Maintenance Manual

USER GUIDE TB-9015
Static Monitor 790
Installation, Operation and Maintenance
Figure 1. SCS Static Monitor

Description

The SCS Static Monitor 790 is designed to monitor the
operation of two wrist strap grounding systems and the
ground connection of a specified equipment chassis.
This product has been designed and tested for indoor
use only and with SCS Dual Conductor Wristbands
2300VM Series and SCS Dual Conductor Ground Cord
2300 Series. The monitor operates from a 120VAC
adaptor that is included in the North America version.
Outside North America, obtain an appropriate AC
adapter meeting the specifications. The product has not
been tested or proven safe for other uses.
Note: SCS Dual Conductor Cords & Wristbands
2300VM Series are required for use with the Static
Monitor 790, ordered separately.
Meets requirements of ANSI/ESD S20.20 and
recommendations of ESD Handbook ESD TR20.20
which includes "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".
AC Adapter
SCS Static Monitor 790
Figure 2. SCS Static Monitor
TB-9015 Page 1 of 7 June 2015
790.
Mounting
Chassis/
Ground
Cords with
Two-Wire
Connector
790 Kit.
SCS - 926 JR Industrial Drive, Sanford, NC 27332 • (919) 718-0000 • Website:

Theory of Operation

The SCS Static Monitor 790 is designed to continuously
monitor the voltage level on an operator(s) using a
high impedance voltage measurement circuit. The
measured operator's voltage is compared to one of four
user selectable (1V, 3V, 6V and 9V) internal reference
voltages. An alarm will sound with a corresponding
red flashing lamp(s), when an operator's voltage level
(caused by static generation) exceeds the selected
internal reference voltage.* In addition, a wristband
contact detection circuit is also employed to let the user
know if the wristband is being worn improperly or has
experienced a loss of continuity between the ground
cord and wristband.
The ground connection of the Static Monitor 790 is
continuously monitored through a low DC current-loop
measurement circuit. The ground connection of an
equipment chassis can also be monitored when
connected in series with the monitor's ground
measurement circuit. An alarm will sound with
corresponding red lamps, when this loop resistance
exceeds 10 ohms.**
If all monitored components are operating within the
selected operating parameters of the Static Monitor 790,
a green lamp will illuminate.
The Static Monitor 790 uses a modified version of the
SCS Dual Conductor Wristband (VM Series) and the
standard SCS Dual Conductor Grounding Cord (See
Accessories Section).
*Voltage alarm levels ±15%
**Ground disconnect ±20%
CAUTION: The SCS Static Monitor 790 does not have
the capability of verifying that the ground point is a
suitable ground. If you are not sure what a suitable
ground is, contact a licensed electrician before
installation.
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