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350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
S3 PROTECTION
CHAPTER 6: SETPOINTS
CURVE
Range: Definite Time, Inverse, FlexCurve A, FlexCurve B
Default: Definite Time
This setpoint allows the choice of one of three methods to delay the operate signal once
all the conditions are met to discriminate fault direction.
The "Definite Time" selection allows for a fixed time delay defined by the POWER PICKUP
DELAY setpoint.
The "Inverse" selection allows for inverse time characteristics delay t defined by the
following formula:
Eq. 12
where:m is a multiplier defined by the MULTIPLIER setpoint value
S
ref
is the REF POWER PICKUP setpoint value
S
op
is the operating power at the time. This timer starts after the definite time timer
expires.
The "FlexCurve A" and "FlexCurve B" selections allow custom user-programmable time
characteristics. When working with FlexCurves, the element uses the operate power to
reference power ratio, and the multiplier setpoint is not applied:
Eq. 13
NOTE
NOTE:
The TDM for the Flexcurve in this equation is 1.00.
Again, the inverse time timer starts after the definite time timer expires. Inverse time
reset is instantaneous whenever S
op
is less than S
ref
.
MULTIPLIER
Range: 0.01 to 2.00 s in steps of 0.01 s
Default: 1.00 s
This setting is applicable only if the CURVE setpoint above is selected to Inverse. It
defines the multiplier factor m for the inverse time delay.
OUTPUT RELAY X
For details see
BLOCK 1/2/3
For details see
