GE Multilin 489 Instruction Manual page 171

CHAPTER 5: SETPOINTS
5.8.2 Reactive Power
1 REACTIVE
POWER
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
PATH: SETPOINTS S7 POWER ELEMENTS
[ ] BLOCK Mvar ELEMENT
FROM ONLINE: 1 s
REACTIVE POWER
MESSAGE
ALARM: Off
ASSIGN ALARM
MESSAGE
RELAYS (2-5): ---5
POSITIVE Mvar ALARM
MESSAGE
LEVEL: 0.85 x Rated
NEGATIVE Mvar ALARM
MESSAGE
LEVEL: 0.85 x Rated
POSITIVE Mvar ALARM
MESSAGE
DELAY: 10.0 s
NEGATIVE Mvar ALARM
MESSAGE
DELAY: 1.0 s
REACTIVE POWER ALARM
MESSAGE
EVENTS: Off
REACTIVE POWER
MESSAGE
TRIP: Off
ASSIGN TRIP
MESSAGE
RELAYS (1-4): 1---
POSITIVE Mvar TRIP
MESSAGE
LEVEL: 0.80 x Rated
NEGATIVE Mvar TRIP
MESSAGE
LEVEL: 0.80 x Rated
POSITIVE Mvar TRIP
MESSAGE
DELAY: 20.0 s
NEGATIVE Mvar TRIP
MESSAGE
DELAY: 20.0 s
In a motor/generator application, it may be desirable not to trip or alarm on reactive power
until the machine is online and the field has been applied. Therefore, this feature can be
blocked until the machine is online and adequate time has expired during which the field
had been applied. From that point forward, the reactive power trip and alarm elements will
be active. A value of zero for the block time indicates that the reactive power protection is
active as soon as both current and voltage are measured regardless of whether the
generator is online or offline. Once the 3-phase total reactive power exceeds the positive
or negative level, for the specified delay, a trip or alarm will occur indicating a positive or
negative Mvar condition. The level is programmed in per unit of generator rated Mvar
calculated from the rated MVA and rated power factor. The reactive power elements can
be used to detect loss of excitation. If the VT type is selected as "None" or VT fuse loss is
detected, the reactive power protection is disabled. Rated Mvars for the system can be
calculated as follows:
REACTIVE POWER
Range: 0 to 5000 s in steps of 1
Range: Off, Latched, Unlatched
Range: Any combination of Relays 2 to
5
Range: 0.02 to 2.01 × Rated in steps of
0.01
Range: 0.02 to 2.01 × Rated in steps of
0.01
Range: 0.2 to 120.0 s in steps of 0.1
(lagging vars, overexcited)
Range: 0.2 to 120.0 s in steps of 0.1
(leading vars, underexcited)
Range: On, Off
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to
4
Range: 0.02 to 2.01 × Rated in steps of
0.01
Range: 0.02 to 2.01 × Rated in steps of
0.01
Range: 0.2 to 120.0 s in steps of 0.1
(lagging vars, overexcited)
Range: 0.2 to 120.0 s in steps of 0.1
(leading vars, underexcited)
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