Reactive Power (40Q) - GE 889 Instruction Manual

CHAPTER 4: SETPOINTS

Reactive Power (40Q)

889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
In a generator application, the reactive power element can be used to detect excitation
system malfunctions, such as under excitation, loss of excitation, etc. Once the 3-phase
total reactive power exceeds the positive or negative level for the specified delay, a trip or
alarm occurs 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.
VTFF detection can be used to block this function.
Path:
Setpoints > Protection > Group 1 > Power > Reactive Power
TRIP FUNCTION
Range: Disabled, Trip, Configurable
Default: Disabled
This setting enables the Reactive Power Trip functionality.
POSITIVE VAR TRIP PICKUP
Range: 0.02 to 2.00 x Rated in steps of 0.01
Default: 0.80 x Rated
This setting specifies a pickup threshold for the positive MVAR trip function. The level is
programmed as a multiple of Rated MVAR calculated from the rated MVA and rated
power factor. Rated reactive power is calculated as follows:
Rated Reactive Power = Rated MVA x sin(cos
Rated MVA and Rated Power Factor are programmed under Path:
.
Generator
NEGATIVE VAR TRIP PICKUP
Range: 0.02 to 2.00 x Rated in steps of 0.01
Default: 0.80 x Rated
This setting specifies a pickup threshold for the negative var trip function.
POSITIVE VAR TRIP DELAY
Range: 0.00 to 600.00 s in steps of 0.01 s
Default: 10.00 s
This setting specifies a time delay for the positive var trip function. Once the 3-phase
total reactive power exceeds the positive level for the duration of the Positive var Trip
Delay time, a trip will occur indicating a positive var condition.
NEGATIVE VAR TRIP DELAY
Range: 0.00 to 600.00 s in steps of 0.01 s
Default: 1.00 s
This setting specifies a time delay for the negative var trip function.
TRIP RELAY X
For details see Common
ALARM FUNCTION
Range: Disabled, Alarm, Latched Alarm
Default: Disabled
This setting enables the Reactive Power alarm functionality.
POSITIVE VAR ALARM PICKUP
Range: 0.02 to 2.00 x Rated in steps of 0.01
Default: 0.85 x Rated
This setting is typically set at a level less than the Positive var Trip Pickup for the alarm
function.
-1
(Rated Power Factor))
Setpoints.
PROTECTION
Setpoints > System >
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