Sel 751A - Trip;Close Logic; Trip;Close Logic Settings; Table 4.24 Time Window Versus 81 Rntp Setting; Table 4.25 Trip;Close Logic Settings

4.50
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Trip/Close Logic
Set 81Rn Trend to INC or DEC to limit operation of the element to increasing
or decreasing frequency respectively. Also, when set to INC or DEC the
element is supervised by nominal frequency, FNOM. Set the trend to ABS if
you want the element to disregard the frequency trend.
Voltage and current supervision: A minimum positive sequence Voltage and/
or Current is required for the operation of 81R element when the levels are
specified by the 81RISUP and 81RVSUP settings respectively. Set
81RISUP := OFF if no current supervision is required and similarly
81RVSUP := OFF if no voltage supervision is required. In any case, the
element is also supervised by Relay Word FREQTRK, which ensures that the
relay is tracking and measuring the system frequency.
Use the Relay Words 81RnT to operate output contacts to open appropriate
breaker(s) as required by your load shedding scheme.
Trip/Close Logic
Trip/Close Logic
Settings
Table 4.24 Time Window Versus 81RnTP Setting
81RnTP Setting (Hz/sec) Time-Window (Cycles)
15.00-2.33 3
2.32-1.17 6
1.16-0.78 9
0.77-0.58 12
0.57-0.47 15
0.46-0.38 18
0.37-0.33 21
0.32-0.29 24
0.28-0.26 27
< 0.25 30
Table 4.25 Trip/Close Logic Settings (Sheet 1 of 2)
Setting Prompt Setting Range
Setting Name := Factory
Default
MIN TRIP TIME 0.0–400.0 sec
TDURD := 0.5
CLOSE FAIL DLY OFF, 0.0–400.0 sec
CFD := 1.0
TRIP EQUATION SV
TR := ORED50T OR ORED51T
OR 81D1T OR 81D2T OR 81D3T
OR 81D4T OR 59P1T OR 59P2T
OR 55T OR REMTRIP OR SV01
OR OC OR SV04T
REMOTE TRIP EQN SV
REMTRIP := 0
UNLATCH TRIP SV
ULTRIP := NOT (51P1P OR
51G1P OR 51N1P OR 52A)
BREAKER STATUS SV
52A := 0