GE 845 Instruction Manual page 265

CHAPTER 4: SETPOINTS
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
IEC A/B/C and Short Inverse;
IAC Extremely/Very/Inverse/Short Inverse;
FlexCurve A/B/C/D, I2t, I4t,
Default: IEEE Moderately Inverse
TDM
Range: 0.05 to 600.00 in steps of 0.01
Default: 1.00
The setting provides a selection for Time Dial Multiplier which modifies the operating
times per the selected inverse curve. For example, if an IEEE Extremely Inverse curve is
selected with TDM = 2, and the fault current is 5 times bigger than the PKP level, the
operation of the element will not occur before 2.59 s have elapsed after Pickup.
RESET
Range: Instantaneous, Timed
Default: Instantaneous
Selection of an Instantaneous or a Timed reset time is provided using this setting. If
Instantaneous reset is selected, the Phase TOC element will reset instantaneously
providing the current drops below 97-98% of the Phase TOC PKP level. If Timed reset is
selected, the time to reset is calculated based on the reset equation for the selected
inverse curve.
DIRECTION
Range: Disabled, Forward, Reverse
Default: Disabled
VOLTAGE RESTRAINT
Range: Disabled, Enabled
Default: Disabled
This setting enables or disables the Voltage Restraint function for the TOC element.
When set to "Enabled" this feature lowers the Pickup value of each individual Phase Time
Overcurrent element in a fixed relationship with its corresponding phase input voltage.
Figure 4-62: Voltage Restraint characteristics for Phase TOC
BLOCK
Range: Off, Any operand from the list of FlexLogic operands
Default: Off
RELAYS
Range: Do Not Operate, Operate
Default: Do Not Operate
PROTECTION
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