GE 845 Instruction Manual page 329

CHAPTER 4: SETPOINTS
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
MINIMUM VOLTAGE
Range: 0.00 to 1.50 x VT in steps of 0.01 x VT
Default: 0.20 x VT
This setting sets the minimum operating voltage for the undervoltage Pickup level
specified per times VT.
For example, a PKP setting of 0.20 x VT with 13800:115 VT translates into 2.76kV (or 23V
secondary).
If the Mode setting selection is Phase to Phase and the Setpoints/System Setup/Voltage
Sensing/Phase VT Connection selection is Wye, the previous example translates to a
Phase to Phase voltage value of 2.76kV x 1.732 = 4.78kV.
PHASES FOR OPERATION
Range: Any One, Any Two, All Three
Default: Any One
This setting defines the number of voltages required for operation of the Phase UV
protection function.
UNDERVOLTAGE CURVES
Range: Definite Time, Inverse Time, FlexCurves A/B/C/D
Default: Definite Time
This setting provides the selection of definite time delay or time delay inverse
undervoltage curves, or FlexCurves. In the case of FlexCurves, the voltage ratio used is
reversed. Refer to the equation and note regarding FlexCurves in the previous section
Undervoltage Curves.
PICKUP DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 1.000 s
If Inverse Time is selected as an Undervoltage Curve setpoint, the Pickup Delay value is
loaded to variable D in the curve formula. For more information, refer to the previous
section Undervoltage Curves.
BLOCK
Range: Off, Any FlexLogic operand
Default: Off
OUTPUT RELAY X
For details see Common
EVENTS
Range: Enabled, Disabled
Default: Enabled
TARGETS
Range: Disabled, Self-reset, Latched
Default: Self-reset
Setpoints.
PROTECTION
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