Negative Sequence Overcurrent - GE 489 Instruction Manual

4 SETPOINTS
The 489 phase overcurrent restraint voltages and restraint characteristic are shown below:
Phase Overcurrent Restraint Voltages:
CURRENT VOLTAGE
IA Vab
IB Vbc
IC Vca
808792A3.CDR
PATH: SETPOINTS S5 CURRENT ELEMENTS
NEGATIVE SEQUENCE
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Rotor heating in generators due to negative sequence current is a well known phenomenon. Generators have very specific
capability limits where unbalanced current is concerned (see ANSI C50.13). A generator should have a rating for both con-
tinuous and also short time operation when negative sequence current components are present.
GE Multilin
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
Figure 4–2: VOLTAGE RESTRAINT CHARACTERISTIC
NEGATIVE SEQUENCE
ð
NEGATIVE SEQUENCE
ENTER
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ESCAPE ALARM: Off
ASSIGN ALARM
ESCAPE
RELAYS (2-5): ---5
MESSAGE
NEG. SEQUENCE ALARM
ESCAPE
PICKUP: 3% FLA
MESSAGE
NEGATIVE SEQUENCE
ESCAPE
ALARM DELAY: 0.5 s
MESSAGE
NEGATIVE SEQUENCE
ESCAPE
ALARM EVENTS: Off
MESSAGE
NEGATIVE SEQUENCE
ESCAPE
O/C TRIP: Off
MESSAGE
ASSIGN TRIP
ESCAPE
RELAYS (1-4): 1---
MESSAGE
NEG. SEQUENCE O/C
ESCAPE
TRIP PICKUP: 8% FLA
MESSAGE
NEG. SEQUENCE O/C
ESCAPE
CONSTANT K: 1
MESSAGE
NEG. SEQUENCE O/C
ESCAPE
MAX. TIME: 1000 s
MESSAGE
NEG. SEQUENCE O/C
ESCAPE
RESET RATE: 227.0 s
MESSAGE
489 Generator Management Relay
4.6 S5 CURRENT ELEMENTS
0.1 0.2 0.3 0.4 0.5 0.6
Phase-Phase Voltage / Rated Phase-Phase Voltage

4.6.6 NEGATIVE SEQUENCE OVERCURRENT

Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to 5
Range: 3 to 100% FLA in steps of 1
Range: 0.1 to 100.0 s in steps of 0.1
Range: On, Off
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to 4
Range: 3 to 100% FLA in steps of 1
Range: 1 to 100 in steps of 1
Range: 10 to 1000 s in steps of 1
Range: 0.0 to 999.9 s in steps of 0.01
0.7 0.8 0.9 1
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