I-GARD Gemini Instruction Manual
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1
GENERAl DESCRIPTION
To increase reliability in High-Resistance-Grounded power systems, I-Gard has introduced the
Gemini
Grounding Resistor system, which you have purchased. The resistor provides a return path for hazardous
capacitive currents, which can break down the system insulation under conditions of intermittent ground faults.
The
Gemini
provides a dual resistor element to double the reliability of the resistor elements. Two separate
elements are used to provide redundancy thus providing protection in the event of an open circuit failure of one
of the elements.
A versatile ground fault relay I-Gard Type
GFR-RM
in the
Gemini
system indicates the presence of ground
faults that may occur on the power system by current measurement within the Gemini unit itself
,
in addition to
providing a monitor that will operate a local and remote Alarm if the value of the Grounding resistor elements
changes to a lower or higher limit set by the user.
When a
single
ground fault occurs:
Gemini
controls and limits the fault current.
Gemini
provides alarms that
indicate the presence of an active fault, and if equipped with the optional Pulsing relay, plant electrical personnel
may follow a simple sequence to locate and isolate the fault without interrupting or opening circuit breakers.
This allows for the uninterrupted operation of process equipment.
Faults are indicated by front panel lights. The TRIP lamp lights whenever a Ground Fault or a Resistor fault is
detected. Separate lights for GROUND FAULT and RESISTOR FAULT indicate which condition caused the Trip
lamp to turn on. Two form C contacts are available for the user’s application
- one for Ground Fault and the other
for Resistor Fault. See Wiring Diagram Figure 1 for details.
A meter scaled from 0-100% is supplied on the front of the panel. This meter indicates the amount of ground
fault current present relative to the let through current.
A TEST button on the front panel allows a confidence check of the Gemini unit. When pressed, the Gemini will
go into the Alarm condition with SYSTEM HEALTHY lamp extinguishing and RESISTOR FAULT, GROUND FAULT,
50% of the available round fault current. The user can modify the duration of this pulse to suit the requirements
If supplied, the
Gemini
pulsing system, when activated, will cyclically limit the ground fault current to 100%
and
The cyclic pulsing, combined with the hand held current sensor and a single line diagram, can be used to rapidly
locate a ground fault even in a very complex power distribution system.
of his sensing device.
and TRIP lamps illuminating. The corresponding contacts will operate to energize the user
'
s devices if connected.
