CHAPTER 6: SETPOINTS S3 PROTECTION
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 6–77
NEG SEQ TOC1(2) TDM
Range: 0.05 to 50.00 in steps of 0.01
Default: 1.00
This setting provides a selection for Time Dial Multiplier, which modifies the time
response of the selected curve. 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 the elapse of 2.59 seconds from pickup.
NEG SEQ TOC1(2) RESET
Range: Instantaneous, Linear
Default: Instantaneous
The reset of the negative sequence timed overcurrent can be selected as either
“Instantaneous” or “Linear”. If Instantaneous reset is selected, the Negative Sequence
TOC element will reset instantaneously providing that the current drops below 97-98%
of the Neg. Seq. TOC PKP level, before the time for operation is reached. When Linear
reset is selected, the time to reset is calculated based on the following linear equation:
Eq. 20
where: T
RESET
- reset time in seconds; E - energy capacity reached (per unit); M - curve
multiplier; C
R
- characteristic constant (5 for ANSI, IAC, Definite Time, and FlexCurves
TM;
8
for IEC curves).
The 100% “energy capacity” for the TOC element is defined by the selection of PKP, TDM
and points from the inverse curve. A memory variable based on actual values currents is
monitored for accumulation of energy capacity, where if it reaches a level of 100% of
the set energy capacity level, the element operates, and if it goes below 97-98% of this
level, the element will tend to reset. The accumulated energy capacity is used as an
input for computation of the reset time, when the “Linear” reset is selected as a setting.
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 a function for the Negative Sequence TOC
element. One, or both, trip output relays can be selected to operate under the Negative
Sequence TOC operating condition.
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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