I-Gard MGFR Series, Инструкция по эксплуатации

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A green POWER indicator lights when the MGFR is energized with control power.
Though the fault current is computed at approximately 2 msec intervals, the display is updated every 1 sec with the
new value. If a sustained fault current value is less than 1.00 per unit, the relay will never trip and the value will be
displayed for monitoring purposes.
All models are capable of displaying fault values from 0-99.9 times of the pick-up setting. The actual fault current
may be computed from the formula,
Fault current = Reading X Pick up Setting ------- (2)
When there is no fault, ideally, the relay should show ‘0.00’. In practice, the output of ZSCS may not be exactly zero
due to any small leakage in the system. In this case, the display will not be ‘0.00’ and will show the RMS value of the
vector sum of currents in all four conductors in a 3-phase 4-wire system.
2.5 TRIP INDICATOR
2.5.1 MGFR-SE-ZB
For service entrance models (type MGFR-SE-ZB) an electromagnetic status indicator provides trip indication.
If the control power supply of the relay is taken from the load side of a breaker, the indicator will show ‘red’
after tripping due to a fault. The indicator will maintain the same status even when the control power is off after
tripping the breaker. When the breaker is switched on, the relay will re-energize and will automatically reset the
indicator to ‘black’ colour. On the other hand, if the supply is taken from the line side of breaker or from UPS,
the target can be manually reset by a momentary push button on the faceplate. The relay itself is also reset on
power up.
2.5.2 ALL OTHER MODELS OF MGFR
All the relays have a red LED light for trip indication, which is manually reset by a momentary push button on the
faceplate. The button function will be explained in detail in the next section. If the relay power supply is taken
from the load side of a breaker, the relay will trip the breaker upon a fault, but will be de-energized after tripping
the breaker and the indication will be lost. To avoid this, it is recommended that the control power supply should
be taken from the line side of the breaker.
2.6 RESET CONTROL
2.6.1 ALL MODELS
In all MGFR-( )-ZB relays provision has been made to, either, have the trip relay reset automatically (self-reset),
or have it stay tripped after the fault has been cleared until an operator has pressed the RESET button on the
front of the relay (manual reset). The relay is shipped in the self-reset mode, but manual reset can be selected
by connection of a jumper across the SELF/MANUAL RESET terminals at the rear of the relay.
Note, in either case, self or manual reset, the Indicator lamp (or target in -SE types) will remain indicating that
the relay had tripped until the RESET button has been pushed by an operator. (Assuming the control power has
not been interrupted in the mean time, of course.) In other words, the operation of the Indicator is not affected
by the self/manual reset selection.
See also Section 2.5 (TRIP INDICATOR and 2.7.3 (TRIP INHIBIT)