GE 339

CHAPTER 6: SETPOINTS S3 PROTECTION
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL 6–49
Short circuit (50P)
If Short Circuit is enabled, a trip or alarm occurs once the magnitude of any phase current
exceeds the setting S/C PKP for the time specified by the setting S/C DELAY.
A second independent Short Circuit protection element is provided for High Speed. If two-
speed functionality is enabled, the 339 relay relies on the motor speed indication to switch
the Short Circuit settings as per the motor running speed, so the main Short Circuit is only
active when the motor is running at low speed, and the High Speed Short Circuit is only
active when the motor is running at high speed. If two-speed functionality is not deployed,
only the main Short Circuit is active, and the High Speed Short Circuit is disabled.
Short Circuit operation is a serious event, and therefore results in a lockout that cannot be
reset unless an Emergency Restart or a Lockout Reset is issued.
NOTE
NOTE:
Warning: care must be taken when turning on this feature. If the interrupting device
(contactor or circuit breaker) is not rated to break the fault current, the function of this
feature should not be programmed as TRIP. Alternatively, this feature may be programmed
as ALARM or LATCHED ALARM and assigned to an auxiliary relay connected to an
upstream device which is capable of breaking the fault current.
PATH:
SETPOINTS > S3 PROTECTION > SHORT CIRCUIT
S/C FUNC
Range: Disabled, Latched Alarm, Alarm, Trip
Default: Disabled
For details see Common setpoints
.
S/C PKP
Range: 1.00 to 20.00xCT in steps of 0.01xCT
Default: 6.00xCT
This setting specifies a pickup threshold for the Short Circuit.
S/C DELAY
Range: 0.00 to 60.00 s in steps of 0.01 s
Default: 0.00 s
This setting specifies a time delay for the Short Circuit.
OUTPUT RELAY X
For details see Common setpoints
.
BLOCK 1 to 3
For details see Common setpoints
.