CHAPTER 6: SETPOINTS S3 PROTECTION
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–61
PHASE CT INPUTS
Range: CT(W1), CT(W2)
Default: CT(W1)
The Phase Timed Overcurrent menu provides the selection of either CT(W1) input
currents or CT(W2) currents. If CT(W1) is selected, the PH TOC element will use the ratings
of the Winding 1 CTs entered on the relay under SYSTEM SETUP/S2 CURRENT SENSING. If
the CT(W2) setting is selected, the relay will use the CT ratings associated with
transformer Winding 2.
PH TOC1(2) PKP
Range: 0.05 to 20.00 x CT in steps of 0.01 x CT
Default: 1.00 x CT
This setting sets the time overcurrent pickup level, specified as times CT. For example, a
PKP setting of 0.9 x CT with 300:5 CT translates into 270A primary current.
PH TOC1(2) CURVE
Range: ANSI Extremely/Very/Moderately/Normally Inverse, Definite Time, IEC Curve A/B/C
and Short Inverse, IAC Extremely/Very/Inverse/Short
Default: Extremely Inverse
This setting sets the shape of the selected inverse curve.
PHASE TOC1(2) TDM
Range: 0.50 to 50.00 in steps of 0.01
Default: 1.00
This setting provides the selection for Time Dial Multiplier by which the times from the
inverse curve are modified. For example if an ANSI Extremely Inverse curve is selected
with TDM = 2, and the fault current was 5 times bigger than the PKP level, the operation
of the element will not occur before an elapsed time after pickup, of 2.59 seconds.
PH TOC 1(2) RESET
Range: Instantaneous, Linear
Default: Instantaneous
The “Instantaneous” reset method is intended for applications with other relays, such as
most static relays, which set the energy capacity directly to zero when the current falls
below the reset threshold. The “Timed” reset method can be used where the relay must
coordinate with electromechanical relays.
RLY1 TRIP W1 BKR and RLY2 TRIP W2 BKR
Range: Do not operate, Operate
Default: Do not operate
The menu for the two trip output relays - RLY1 TRIP W1 BKR and RLY2 TRIP W2 BKR - is
available only if the Trip setting is selected as the function for the Phase Timed
Overcurrent element. One or both trip output relays can be selected to operate upon
Phase TOC operation.
NOTE:
The "RLY1 TRIP W1 BKR" and "RLY2 TRIP W2 BKR" setpoints will be displayed on the OC
menu regardless of the selected OC function. These output relays will not operate if either
Alarm or Latched Alarm is selected as an OC function, regardless of the Operate/Do Not
Operate value selected. The output relays are operational only if the OC function is
selected as Trip.
OUTPUT RELAY X
For details see Common setpoints
.
BLOCK 1/2/3
For details see Common setpoints
.
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