MGFR
TheTheMGFR
MGFR series
series ofof ground
ground faultfault
relaysrelays are microprocessor
are microprocessor based based
relays that measure the ground fault current from the
relays that measure the ground fault current from the secondary of a secondary
of a zero sequence current sensor connected to the relay. When
zero sequence current sensor connected to the relay. When a ground
a ground fault occurs, the relay computes the RMS value of the
fault occurs, the relay computes the RMS value of the fault current. If
fault current. If the fault current is above the level of the pick-
upthe fault current
setting of theisrelay,
above the
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trip ofunit
the operates
pick up setting of the relay,
to open the
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a set current
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programmable time current characteristics.
The MGFR series has five basic models each with eight discrete
The MGFR series has five basic models each with eight discrete pick-up
pick-up and time settings. The range of the pick-up settings varies
andmodel
from time settings. The range
to model. Theofentire
the pick-up settings
series coversvaries
thefrom model
range from 10
mAtoto
model.
1200The entire series covers the range from 10mA to 1200 amps.
Amps.
unparalleled protection
Pick-up settings from 10 mA to 1200 Amps with discrete time settings
Visual display of leakage current measured by the zero sequence current sensor
Suitable for use on solidly grounded and resistance grounded systems
Time coordinated protection and zone selective instantaneous trip modes available
Each of the basic five models is designed to be used in both Zone Selective
Instantaneous Protection (ZSIP) and Time Coordinated Protection (TCP) modes.
A great deal of damage and destruction can be produced by arcing ground faults on
grounded systems. Arcing ground fault damage is directly proportional to the current,
arc voltage and fault duration.
To minimize damage and safety concerns, any one, or all three parameters must be
kept to a minimum.
A single ground fault relay on the main disconnect device is the minimum required by
the code and leads to power interruption of the entire system if a ground fault occurs in
any location.
Where continuity of service is essential, selective ground fault protection should be used.
A selective ground fault protection system is one in which each disconnecting means
is equipped with a ground fault relay so that only the one nearest the ground fault will
be tripped. Selective ground fault protection systems may be either TCP, ZSIP or a
combination of both.
ZSIP achieves the objective of instantaneous response to ground faults. Since it is
fully coordinated, it minimizes damage and maximizes protection. If there is a ground
fault on a circuit protected by a ZSIP relay and the magnitude of the fault current
exceeds the pick-up setting, the relay for that zone will trip instantaneously. Selectivity
between zones is achieved by a signal generated by the first ground fault relay
upstream of the fault, which operates immediately. This signal is sent to all relays
further upstream and restrains them from tripping instantaneously.
The result is maximum protection with minimum service disruption.
7615 Kimbel St., Unit 1
Mississauga, Ontario Canada L5S 1A8
www.i-gard.com Phone . 905-673-1553 Fax . 905-673-8472
Toll Free . 1-888-737-4787
sales@i-gard.com
