I-Gard MGFR Series, Instruction Manual

Page: 12 / 24

The MGFR relays continuously monitor the system for ground fault and check the output of the ZSCS 480 times
in one second in a 60 Hz system. The software is designed to take care of ground faults in a 50-60 Hz range of
power systems. There is a “watchdog” and microprocessor supervision circuit in the relay which continuously
monitors the status of the microprocessor. If they detect any abnormal behaviour in the operation of the relay,
they automatically, reset the processor as a preventive measure. A 5V DC source supplies power to all the
electronics in the relay.
5. SPECIFICATIONS
5.1 SCOPE
The specifications provided in this section cover all models of the MGFR series unless stated otherwise.
5.2 CONTROL POWER
-ZB 120, 60 Hz, 15VA
-AB 240, 50 Hz, 9VA
5.2.1 OPERATING VOLTAGE TOLERANCE
-ZB -AB
Max. Voltage: 130 265 V AC
Min. Voltage: 65 130 V AC
5.3 TEMPERATURE RANGE
Operating Ambient Temperature: 0°C to 70°C*
Storage Temperature: -20°C to 85°C
* Continuous operation at maximum operating temperature is not recommended.
5.4 DIELECTRIC STRENGTH
1500V AC circuit to enclosure for 1 minute.
5.5 DISPLAY
0-99.9 X P.U.
(1.00 P.U. = Pick-up Setting)
5.6 ACCURACY
5.6.1 PICK UP ACCURACY
±10%
5.6.2 TIME DELAY ACCURACY
DMT: ±5%
IDMT: T = K/M1.96 for 1.2 < M < 10
where:
M = Measured multiple of pickup
K = Trip constant (Depends on time band)
T = Trip time
Instantaneous: 2 Cycles on computed RMS at 50/60 Hz
(including ½ cycle delay for dry contact to close)