CHAPTER 6: PROTECTION SETPOINTS FREQUENCY ELEMENTS
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–145
PICKUP
Range: 0.10 to 15.00 Hz/sec in steps of 0.01 Hz/sec
Default: 0.50 Hz/sec
The setting specifies an intended Pickup threshold.
For applications monitoring a decreasing trend, set TREND to “Decreasing” and specify
the Pickup threshold accordingly. The operating condition is: -df/dt > PKP.
For applications monitoring an increasing trend, set TREND to “Increasing” and specify
the pickup threshold accordingly. The operating condition is: df/dt > PKP.
For applications monitoring rate of change of frequency in any direction, set TREND to
“Bi-Directional” and specify the Pickup threshold accordingly. The operating condition
can be either of the above two conditions.
PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 2.000 s
This setting provides a definite Pickup time delay. Instantaneous operation is selected by
a Pickup time delay setting of 0.000 s.
MINIMUM FREQUENCY
Range: 20.00 to 80.00 Hz in steps of 0.01 Hz
Default: 45.00 Hz
The setting defines the minimum frequency level required for operation of the element.
The setting may be used to effectively block the feature based on frequency. For
example, if the intent is to monitor an increasing trend but only if the frequency is
already above certain level, this setting is set to the required frequency level.
MAXIMUM FREQUENCY
Range: 20.00 to 80.00 Hz in steps of 0.01 Hz
Default: 65.00 Hz
The setting defines the maximum frequency level required for operation of the element.
The setting may be used to effectively block the feature based on frequency. For
example, if the intent is to monitor a decreasing trend but only if the frequency is
already below a certain level (such as for load shedding), this setting is set to the
required frequency level.
VT INPUT
Range: dependant upon the order code
Default: Ph VT Bnk1-J2 or LEA Bnk1-J2, Dependant on order code
This setting provides selection of the frequency input.
MINIMUM VOLTAGE
Range: 0.000 to 1.250 x VT in steps of 0.001 x VT
Default: 0.700 x VT
The setting defines the minimum voltage level required for operation of the element. The
supervising function responds to the positive-sequence voltage. Overvoltage supervision
is used to prevent operation under specific system conditions such as faults.
FAST PATH:
If the 3-phase VT uses a delta connection and FREQUENCY INPUT is set to J2-3VT, the
positive sequence voltage is used as the supervision voltage. In such condition, the true
supervision level is internally changed to 1/sqrt(3) of the user setting since the base of VT
here is the phase-phase voltage.
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