CHAPTER 6: SETPOINTS
S3 PROTECTION
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
6–65
Figure 6-27: Neutral Instantaneous Overcurrent Protection: Logic Diagram
SETPOINT
Neutral current (IN)
RUN
SETPOINT
BLOCK 1:
Of
f = 0
NTRL
IOC PICKUP:
IN > PICKUP
BLOCK 2:
Of
f = 0
BLOCK 3:
Of
f = 0
OR
AND
Operate Output Relay 1 (TRIP)
Event Recorder
Transient Recorder
LED:
TRIP
OR
OR
Cold Load PKP
Autoreclose
(per shot settings)
Computed by the relay
Block Inputs
AND
SETPOINT
:
Do Not Operate, Operate
OUTPUT
RELA
Y
X
AND
SETPOINT
NTRL
IOC FUNCTION:
Disabled = 0 Latched
Alarm
Alarm Trip
NTRL
IOC PKP
DL
Y:
SETPOINT
t PKP
0
Event Recorder
Transient Recorder
LED:
ALARM
RESET
Command
AND
S
R
LA
TCH
LED: PICKUP
Neutral IOC PKP
Message:
Neutral IOC OP
898007A2.cdr
SETPOINT
NTRL
IOC DIRECTION
:
Forward
Disabled
Reverse
AND
AND
NRL
DIR Reverse
From NEUTRAL
DIRECTIONAL
NRL
DIR Forward
OR
BLK NTRL
DIR OC UND
AND