GE 339

6–134 339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
S4 CONTROLS CHAPTER 6: SETPOINTS
Figure 6-55: CT failure detection logic diagram
SETPOINTS
OR
OR
AND
SETPOINT
FUNCTION: Disabled = 0 Latched Alarm Alarm
LED: ALARM
RESET
Command
AND
S R
LATCH
3I0 CURRENT PKP
Computed Neutral current (IN)
Event Recorder
Transient Recorder
SETPOINTS
Do Not Operate, Operate
OUTPUT RELAY X
AND
CT Fail OP
SETPOINT
BLOCK 1: Off = 0 BLOCK 2: Off = 0 BLOCK 3: Off = 0
OR
AND
3I0 > PKP
RUN 3V0 VOLTAGE INHIBIT
3V0
> INHIBIT LEVEL
RUN
Neutral voltage (VN)
GND CURRENT INHIBIT
Ig > INHIBIT LEVEL
RUN
Ground current (Ig)
SETPOINTS
OR
t
TIME DELAY
SETPOINT
pkp
20 ms
CT Fail PKP
CT Fail DPO
898844A2.CDR