I-Gard GCHK-100, Instruction Manual

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GCHK-100 Instruction Manual I-GARD
7
Ground Check
Ground Check is achieved by the use of a pilot wire (GC). This wire is usually a part of the power cable.
It is used to carry a monitoring current to the machine being monitored. The pilot wire must be properly
terminated at its end point (the machine being monitored). A zener diode terminator such as the GCHK-ZT
or equivalent is required.
The ground terminal must be connected to a reliable system ground. This provides a return path for the
current and completes the ground check loop. Ensure that all wires are firmly connected to eliminate adding
resistance to the system.
Frame Voltage
The Frame Voltage monitor is an additional feature that is monitored through the ground-check pilot wire.
No additional wiring is required for the Frame Voltage monitor.
7
Setup
The GCHK-100 can be operated in different modes selectable with Switch 1. See Table 7.1
Normal mode is with a non-energized TRIP relay which becomes energized when the trip level is exceeded for
a duration exceeding the selected time delay. Alternatively, the FAILSAFE mode can be selected which allows
operation with an energized TRIP relay. This permits disconnection of the TRIP device in the event that power is
interrupted in the case (for example) of loss of a control fuse. Note for Failsafe operation, the control power must
be connected to a source that is not interrupted by the breaker trip operation.
Table 7.1 MODeS Of OpeRaTiON (SWiTCH 1)
function 1 2 3 4 5 6 7
Normal Mode 0
Failsafe Mode X
Normal Trip 0
Pulse Trip X
Manual Reset 0
Auto Reset X
Note:
X indicates switch is on.
Note: Failsafe operation does not apply to the auxiliary relays – only the TRIP relay.
TRIP operation can be modified by use of Switch 1 position 2. When ON the contacts of the TRIP relay are
pulsed instead of continuous. This function reduces the duty cycle of TRIP coils which are not continuously
rated and do not have auxiliary contacts which open and remove the trip current.