Schweitzer Engineering SEL-351P - Additional Settings Example; Other Settings Considerations

6-20 Close and Reclose Logic Date Code 990215
SEL-351P Manual Técnico
recloser status indication is slow – the fast curve/instantaneous trip operation (reclose initiation)
occurs before the SEL-351P sees the recloser close.
If a flashover occurs in a recloser tank during an open interval (recloser open and the SEL-351P
calls for a trip), the SEL-351P goes immediately to lockout.
Additional Settings Example
The preceding settings example initiates open interval timing on rising edge of the TRIP Relay
Word bit. The following is an example of reclose initiation on the opening of a circuit breaker.
Presume input IN101 is connected to a 52a circuit breaker auxiliary contact (52A = IN101).
With setting:
79RI = !52A
the transition of the 52A Relay Word bit from logical 1 to logical 0 (breaker opening) initiates
open interval timing. Setting 79RI looks for a logical 0 to logical 1 transition, thus Relay Word
bit 52A is inverted in the 79RI setting [!52A = NOT(52A)].
The reclose initiate supervision setting 79RIS supervises setting 79RI. With settings:
79RI = !52A
79RIS = TRIP
the transition of the 52A Relay Word bit from logical 1 to logical 0 initiates open interval timing
only if the TRIP Relay Word bit is at logical 1 (TRIP = logical 1). Thus, the TRIP Relay Word
bit has to be asserted when the circuit breaker opens in order to initiate open interval timing.
With a long enough setting of the Minimum Trip Duration Timer (TDURD), the TRIP Relay
Word bit will still be asserted to logical 1 when the circuit breaker opens (see Figure 5.1 and
Figure 5.2 in Section 5: Trip and Target Logic).
If the TRIP Relay Word bit is at logical 0 (TRIP = logical 0) when the circuit breaker opens
(logical 1 to logical 0 transition), the relay goes to the Lockout State. This helps prevent reclose
initiation for circuit breaker openings caused by trips external to the relay.
If circuit breaker status indication (52A) is slow, the TRIP Relay Word bit should be removed
from ULCL setting (unlatch close; see Figures 1.21 and 6.1 and accompanying explanation)
when 79RI = !52A. Making this change to the ULCL setting keeps the SEL-351P from going to
lockout prematurely for an instantaneous trip after an auto-reclose; by not turning CLOSE off
until the circuit breaker status indication tells the relay that the breaker is closed. The circuit
breaker anti-pump circuitry should take care of the TRIP and CLOSE being on together for a
short period of time.
Other Settings Considerations
1. In the preceding additional setting example, the reclose initiate setting (79RI) includes input
IN101, that is connected to a 52a breaker auxiliary contact (52A = IN101).
79RI = !52A