GE D90 Plus - Page 557

CHAPTER 11: METERING PHASOR MEASUREMENT UNIT
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 547
The following settings are available for each PMU.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the PMU frequency rate of change triggering function.
Raise
Range: 0.10 to 15.00 Hz/s in steps of 0.01
Default: 0.25 Hz/s
This setting specifies the pickup threshold for the rate of change of frequency in the
rising direction (positive df/dt). The comparator applies a 3% hysteresis.
Fall
Range: 0.10 to 15.00 Hz/s in steps of 0.01
Default: 0.25 Hz/s
This setting specifies the pickup threshold for the rate of change of frequency in the
falling direction (negative df/dt). The comparator applies a 3% hysteresis.
Pickup Time
Range: 0.00 to 600.00 seconds in steps of 0.01
Default: 0.10 seconds
This setting can be used to filter out spurious conditions and avoid unnecessary
triggering of the recorder.
Dropout Time
Range: 0.00 to 600.00 seconds in steps of 0.01
Default: 1.00 seconds
This setting can be used to extend the trigger after the situation returns to normal. This
setting is of importance when using the recorder in the forced mode (recording as long
as the triggering condition is asserted).
Block
Range: any metering logic operand or shared operand
Default: OFF
Assertion of the operand assigned to this setting blocks operation of the PMU frequency
rate of change triggering function.
Events
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the logging of PMU frequency rate of change
triggering events in the sequence of events recorder.
The figure shows the logic for the PMU frequency rate of change triggering function.