GE 889 - Page 411

CHAPTER 4: SETPOINTS MONITORING
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–281
Figure 4-111: Thermal Model Logic Diagram
894144.CDR
SETPOINTS SETPOINTS
BLOCK:
Phase Currents
Trip Time Constant:
IA RMS IB RMS IC RMS Off=0
Configurable
RUN
SETPOINTS
S
R
FUNCTION:
Disabled=0
OR
FLEXLOGIC OPERAND
THERMAL OL OP
AND AND
OR
LED: ALARM
LATCH
S
R
RESET
Command
Alarm Latched Alarm
FLEXLOGIC OPERAND
THERMAL OL PKP
AND
SETPOINT
Relays
Do Not Operate, Operate
SETPOINTS
Overload Factor:
IA > OL x Ib
IB > OL x Ib IC > OL x Ib
OR
AND
Min. Reset Time:
RUN
SETPOINTS
t
I
Reset Time Constant:
OL x IB
TC
used
≥ 100%
TC
used
< 5%
FLEXLOGIC OPERAND
THERMAL RESET:
Off=0
t
I
OL x Ib
Reset TC
used
= 0