Sel 751A - Synchrophasor Measurement; Breaker Failure Setting; Table 4.41 Setting Group Selection; Table 4.42 Breaker Failure Setting

4.94
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Synchrophasor Measurement
Group Selection
The TGR setting defines the amount of time that the SS1, SS2, and SS3
SEL
OGIC control equation logic results must remain stable before the relay
enables a new setting group. Typically, a one-second delay is sufficient.
SS1, SS2, and SS3 are SEL
OGIC control equations that help define when
setting Group 1, 2, and 3 are active. With the settings shown above, SS1 is set
equal to logical 1, thus setting Group 1 always is active.
Synchrophasor Measurement
The SEL-751A relay provides Phasor Measurement Control Unit (PMCU)
capabilities when connected to an IRIG-B time source. See Appendix H:
Synchrophasors for description and Tabl e H.1 for the settings.
Breaker Failure Setting
The SEL-751A provides flexible breaker failure logic (see Figure 4.51). In the
default breaker failure logic, assertion of Relay Word bit TRIP starts the BFD
timer if the sum of positive-sequence and negative-sequence currents is above
0.02 • I
NOM
. If the current remains above the threshold for BFD delay setting,
Relay Word bit BFT will assert. Use the BFT to operate an output relay to trip
appropriate backup breakers.
Changing the BFI and/or 52ABF settings can modify the default breaker
failure logic.
➤ Set BFI = R_TRIG TRIP AND NOT IN102 if input IN102 is
manual trip only and breaker failure initiation is not desired
when the tripping is caused by this input.
➤ Set 52ABF = Y if you want the breaker failure logic to detect
failure of breaker/contactor auxiliary contact to operate during
the trip operation as defined by the BFI setting.
Table 4.41 Setting Group Selection
Setting Prompt Setting Range
Setting Name :=
Factory Defau lt
GRP CHG DELAY 0–400 sec TGR := 3
SELECT GROUP1 SEL
OGIC SS1 := 1
SELECT GROUP2 SELOGIC SS2 := 0
SELECT GROUP3 SELOGIC SS3 := 0
Table 4.42 Breaker Failure Setting
Setting Prompt Setting Range
Setting Name :=
Factory Defau lt
52A INTERLOCK Y, N 52ABF := N
BK FAILURE DELAY 0.00–2.00 sec BFD := 0.50
BK FAIL INITIATE SELOGIC BFI := R_TRIG TRIP