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1.0 Description
Overview
The 3M
™
Wrist Strap and Ground Monitor 773 can be used in work areas or other
locations to monitor the ground impedance of metal ground connection in process
tools in semiconductor, disk drive, fl at panel, electronic equipment manufacturing and
other environments. Ground impedance monitoring can be used for up to two points
for metal ground, such as within a tool. The 773 monitor can be used to monitor
the impedance-to-ground and voltage level on two persons wearing dual-wire wrist
straps. The unit incorporates green and red LEDs and an audible alarm, as well as an
output logic signal to a host equipment.
Ground Impedance Monitor—Continuously monitors for ground impedance on one
or two separate channels that are connected to one or two process tools. The alarm
level is set the same for all channels.
Output Signal—An output signal is available for connecting to the tool’s computer
or PLC. The 5V signal is either logic 1 or 0 for indicating the monitored ground
resistance/impedance conditions and for the wrist strap.
Operator Connection
The 773 monitor provides continuous monitoring of operator connection to the
monitor via loop resistance check of operator’s physical presence using a dual-
wire wrist strap.
Voltage on Person Wrist Strap Monitor—The 773 monitor has one additional
feature that allows continuous monitoring for excessive voltage on each operator.
