I-Gard MGFR Series, Инструкция по эксплуатации, Страница: 16 / 24

Reset the trip indicator (DISPLAY TRIP RESET) and try to close the breaker. If relay is responsible for tripping,
the indicator will come up again. Failure of the circuit breaker to close and latch mechanically may be due to
other reasons such as those listed below:
a) Shunt trip solenoid - Check to ensure that the plunger of the solenoid is not inhibited from resetting. Refer
to the circuit breaker instruction manual for mechanical mounting details.
b) Pick-up Setting - Check that there is no ground current exceeding the pick-up setting. If so, that will be
visible from the LED display of relay.
c) Other Trip relay - The breaker may be operated by other devices such as under voltage trip, over current
trip, reverse current trip relays etc.
7.2.3 DISPLAY FLASHING AT 0.00
Check the SELF TEST button to see if it is stuck in pressed condition.
7.2.4 DISPLAY FLASHING ALTERNATELY SHOWING 0.00 AND LAST FAULT VALUE
Check the DISPLAY button to see if it is stuck in pressed condition.
7.2.5 DISPLAY FROZEN, DOES NOT RESPOND TO BUTTONS
Turn off power momentarily to reset the unit.
7.2.6 TARGET RESETS AT BREAKER OPENING OR CLOSING
If an auxiliary DC contactor is being used with the trip contacts, try to use isolated DC supply if the above
problem occurs. If an isolated supply is not available, connect a diode with reverse polarity as shown in Fig. 8.
If the trip contacts are used with AC shunt trip coils, there are various ways to suppress any counter EMF that
might occur. The methods vary depending on applications, types of breaker used etc. Contact I-Gard if necessary.
7.2.7 UNIT TRIPS INSTANTANEOUSLY
The MGFR will trip Instantaneously, without Time Delay, if the Factory supplied jumper is missing from the ZSIP
OUT and ZSIP IN terminals at the rear of the unit.
7.2.8 MAIN RELAY TRIPS
The system has a main breaker relay MGFR-SE-ZB or MGFR-1200-ZB only and no other downstream relays on
the feeders. This can result in a coordination problem because the downstream breakers rely on over current
relays or fuses to clear the fault. They require typically, longer clearing times at ground fault levels and thus the
MGFR on the main is left to clear the fault. Ground Fault relays at the feeder level will be required, preferably
operated in the ZSIP mode for optimum coordination.
If none of the above helps, please contact I-Gard Customer Service (1-888-737-4787) for further advice. The
electronics within the MGFR cannot be adjusted or modified by the user, and any attempt to do so without
authorization from I-Gard may void the warranty.
WARNING: While operating an MGFR, the following points must be kept in mind:
a) If the display is already showing a fault above 0.30 X P.U., do not attempt to change the PICK-UP
setting under this condition. Nuisance tripping may occur.
b) If the display is already showing a fault above pick-up, DO NOT ATTEMPT TO CHANGE TIME
DELAY SETTING OR CURVE SELECTION. Allow the fault to clear or to come down below the pick-
up level before changing the time setting or curve selection.