Current Differential Relay
GARD 8000 SYS RFL Electronics
June 20, 2014 13-21 973.334.3100
Primary Settings Definitions:
Phase Bias (1-10 inc 0.125)
This sets the bias for phase A, B, and C. The setting must be between 0.5A
RMS
and 10A
RMS
(inclusive)
in increments of 0.125A
RMS
. The bias is the minimum operate level for the current differential
algorithms. The operate level can increase for a period following breaker closing (bias boost, section
13.5.1.2.7) or based upon the measured currents in the system (slope characteristic, section 13.5.1.2.8).
Phase Bias Boost Level (0-20 inc 0.125)
This sets the bias boost for phase A, B, and C. The setting must be between 0A
RMS
and 20A
RMS
(inclusive) in increments of 0.125A
RMS
. The bias boost increases the operate level for the current
differential algorithms for a user programmable duration following breaker closing (see bias boost
duration below). Setting this parameter to zero effectively disables it. Boost is used to desensitize the
relay for line charging currents when energizing the line. Generally, the setting can be zero for
overhead lines while a higher value may be required for cables.
For further information see section 13.5.1.2.7.
Phase Bias Boost Duration (50-2000 inc 10)
This sets the duration of bias boost for phase A, B, and C. The setting must be between 50ms and 2s
(inclusive) in 10ms increments. Following a breaker closing the operate level for the current
differential algorithms is increased by the bias boost setting (see above) for the duration set with this
parameter. Boost is used to desensitize the relay for line charging currents when energizing the line.
For further information see section 13.5.1.2.7.
Ground Bias (0.5-10 inc 0.125)
This sets the bias for ground. The setting must be between 0.5A
RMS
and 10A
RMS
(inclusive) in
increments of 0.125A
RMS
. The bias is the minimum operate level for the current differential
algorithms. The operate level can increase for a period following breaker closing (bias boost, section
13.5.1.2.7) or based upon the measured currents in the system (slope characteristic, section 13.5.1.2.8).
Ground Bias Boost Level (0-20 inc 0.125)
This sets the bias boost for ground. The setting must be between 0A
RMS
and 20A
RMS
(inclusive) in
increments of 0.125A
RMS
. The bias boost increases the operate level for the current differential
algorithms for a user programmable duration following breaker closing (see bias boost duration
below). Setting this parameter to zero effectively disables it. Generally, the setting can be 0 for
overhead lines while a higher value may be required for cables.
For further information see section 13.5.1.2.7.
Ground Bias Boost Duration (50-10000 inc 10)
This sets the duration of bias boost for ground. The setting must be between 50ms and 2s (inclusive)
in 10ms increments. Following a breaker closing the operate level for the current differential
algorithms is increased by the bias boost setting (see above) for the duration set with this parameter.
For further information see section 13.5.1.2.7.
Phase Operate Current Slope 1 (0.01-2 inc 0.01)
This sets the slope for the first segment of the slope characteristic for phase A, B, and C. The setting
must be between 0 and 2 (inclusive) in increments of 0.01. The slope characteristic increases the
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