CHAPTER 6: PROTECTION SETPOINTS FREQUENCY ELEMENTS
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–139
MINIMUM VOLTAGE
Range: 0.000 to 1.250 x VT in steps of 0.001 x VT
Default: 0.700 x VT
The setting sets the minimum voltage for Underfrequency element operation specified
per times VT. The setpoint prevents incorrect operation before energization of the source
to the relay location, and during voltage dips.
FAST PATH:
If the 3-phase VT uses a delta connection and SIGNAL INPUT is set to Ph VT Bnk1-J2, 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.
CT INPUT
Range: dependant upon the order code
Default: CT Bank 1-J1 or CT Bank 1-K1, dependant on order code
MINIMUM CURRENT
Range: 0.000 to 30.000 x CT in steps of 0.001 x CT
Default: 0.200 x CT
The setting sets the minimum value of current required on any phase to allow the
Underfrequency element to operate. The setpoint is used to prevent underfrequency
tripping during periods of light load, when this action would have an insignificant effect
on the system. A setting of zero is suspend current supervision.
BLOCK
Range: Off, Any FlexLogic operand
Default: Off
OUTPUT RELAY X
For details see Common Setpoints
.
EVENTS
Range: Enabled, Disabled
Default: Enabled
TARGETS
Range: Disabled, Self-reset, Latched
Default: Self-reset
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