Setup - GE 845 Instruction Manual

CONTROL

Setup

FASTPATH:
4–320
• FlexLogic operand that reports on the operation of the portion of the scheme where
high-set or low-set current supervision is used
• FlexLogic operand that reports on the operation of the portion of the scheme where
52b status supervision is used only
• FlexLogic operand that initiates tripping required to clear the faulted zone. The
Breaker Failure output can be sealed-in for an adjustable period
• Target message indicating a failed breaker has been declared.
Path:
Setpoints > Control > Breaker Failure > BF1(X) > BF1(X) Setup
FUNCTION
Range: Disabled, Retrip, Latched Alarm, Alarm, Configurable
Default: Disabled
When the Retrip function is selected and Breaker Failure is initiated (with re-trip current
supervision), the output relay #1 "Trip" operates but the "ALARM" LED does not turn on.
PH RETRIP SUPERV 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 Retrip level, which when exceeded after Breaker
Failure initiation, will Retrip its own breaker. The setting is set to detect the lowest
expected fault current on the protected circuit.
NTRL RETRIP SUPERV PICKUP
Range: 0.050 to 30.000 x CT in steps of 0.001 x CT
Default: 1.000 x CT
This setpoint specifies the neutral current Retrip level, which when exceeded after
Breaker Failure initiation, will Retrip its own breaker. The setting detects the lowest
expected fault current on the protected circuit. Neutral Retrip current supervision is used
to provide increased sensitivity.
SUPERVISION
Range: Current, 52b & Current, 52b
Default: Current
The setpoint specifies the type of supervision of the Breaker Failure element. There are
three options: current only, breaker status only, or both.
BREAKER CLOSED
Range: Off, Any FlexLogic operand
Default: Off
The setpoint selects the FlexLogic operand (auxiliary switch contact) to indicate that the
circuit breaker is closed.
T1 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 1 logic which is supervised with current
supervision only. 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 as well
as relay processing time and current supervision reset time. In a microprocessor relay
this time is not significant. In the 845 relay, the current magnitude ramps-down to zero
in ¾ of a power cycle after the current is interrupted.
In bulk oil circuit breakers, the interrupting time for currents less than 25% of the
interrupting rating can be significantly longer than the normal interrupting time.
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS