GE 845 Instruction Manual page 449

CHAPTER 4: SETPOINTS
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
T2 PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.120 s
The setting provides a delay for Timer 2 logic which is supervised with current
supervision and breaker status (52b indication). The timer is set to the expected opening
time of the circuit breaker, plus a safety margin intended to overcome the relay
measurement and timing errors, relay processing time, current supervision reset time,
and the time required for the breaker auxiliary contact to open.
T3 PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.120 s
The setting provides a delay for Timer 3 logic which is supervised with breaker status
only (52b indication). The timer is set to the expected opening time of the circuit breaker,
plus a safety margin intended to overcome the relay timing errors, and the time required
for the breaker auxiliary contact to open.
PHASE HIGHSET PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.000 x CT
The setpoint specifies the phase current output supervision level. The setting detects the
lowest expected fault current on the protected circuit.
NEUTRAL HIGHSET PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.000 x CT
The setpoint specifies the neutral current output supervision level. The setting detects
the lowest expected fault current on the protected circuit. Neutral current supervision is
used to provide increased sensitivity.
LOWSET DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 0.000 s
The setting provides the lowest current supervision Pickup. The setting is used in
applications where a change in supervision current level is required (for example:
breakers with opening resistors).
The lowest delay (interval between high-set and low-set) is the expected breaker
opening time.
PHASE LOWSET PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.000 x CT
The setpoint specifies the phase current output supervision level. The setting detects the
lowest expected fault current on the protected circuit where significant change in
current level is expected (for example: breakers with opening resistors).
NEUTRAL LOWSET PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.000 x CT
The setpoint specifies the neutral current output supervision level. The setting detects
the lowest expected fault current on the protected circuit where significant change in
current level is expected (for example: breakers with opening resistors). Neutral current
supervision is used to provide increased sensitivity.
CONTROL
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