Current Differential Relay
GARD 8000 SYS RFL Electronics
June 20, 2014 13-17 973.334.3100
Dual Breaker
Check to enable dual breaker option. This only has effect when a second relay I/O is installed,
providing individual ct inputs for breaker and a half or ring bus applications.
Line Frequency
The user must select either 50Hz or 60Hz line frequency.
Protection Rescaling Factor (0.1-10.0 inc 0.1)
The current measurements used for the protection algorithms are internally adjusted to a normalized
scale based upon the CTs; however, in rare occasions the automatic normalization factors need to be
adjusted. One example would be when the ct ratio is badly matched to the available fault current so
that the setting ranges do not cover the required pickup setting. The protection current measurements
are divided by the protection rescaling factor prior to being processed by the algorithms. In most
applications this parameter should be left at 1.0 and should only be changed following consultation
with RFL.
The protection rescaling factor must be between 0.1 and 10 (inclusive) in increments of 0.1. The
protection rescaling factor must be set to the same value in both relays.
Local CT Nameplate
Local Primary CT Factor (50-6000 inc 50)
The user must set the primary CT factor from the nameplate rating. The acceptable range is 50 to 6000
(inclusive) in increments of 50. The primary ratio for a 2000/5 ct is 2000, for example.
Local CT Secondary Factor
The user must select the secondary factor for the CT. The available options are 1A
RMS
and 5A
RMS
.
Remote CT Nameplate
Remote 1 and 2 Primary CT Factor (50-6000 inc 50)
The user must set the primary CT factor from the nameplate rating. The acceptable range is 50 to 6000
(inclusive) in increments of 50. Note that the remote ct ratio setting is part of the communications
checks exchanged between the relays so it this factor does not match what is set in the remote end, a
communications alarm will be issued.
Remote 1 and 2 CT Secondary Factor
The user must select the secondary factor for the CT. The available options are 1A
RMS
and 5A
RMS
.
Fault Detectors
Phase Overcurrent Fault Detector (0.125-15 inc 0.125)
This is used to set the threshold for the overcurrent fault detectors for phase A, B, and C. The setting
must be between 0.125A
RMS
and 20A
RMS
(inclusive) in increments of 0.125A
RMS
.
See section 13.5.1.1.1 for further information.
Ground Overcurrent Fault Detector (0.125-15 inc 0.125)
This is used to set the threshold for the overcurrent fault detector for ground. The setting must be
between 0.125A
RMS
and 20A
RMS
(inclusive) in increments of 0.125A
RMS
.
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