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Date Code 20000421
Maintenance and Testing
7-21
SEL-251, -2, -3 Instruction Manual
6. Apply 5 amps of current to only one phase of the relay. The TRIP output
contacts immediately assert (5 A > 50L = 4.00 A; TR =
50L
) and the circuit
breaker simulator trips open (IN5 = 52A is de-energized).
7. Turn off the current and the TRIP output contact deasserts. Then the external
and reclosing relay open interval timers start.
After the open interval timer expires, the CLOSE output contact asserts. This
stops the external timer and closes the circuit breaker simulator (IN5 = 52A is
energized).
8. Record the time on the external timer and reset it. With the circuit breaker
simulator closed, the reclosing relay reset interval timer runs.
The reset interval timer is set for 1800 cycles, so to check the next open interval
timer, reapply 5 amps of current to only one phase of the relay before the reset
interval expires. Repeat the sequence starting at Number 6.
9. Compare the recorded times to the respective open interval times you monitored.
You should expect consecutive open intervals of 60, 600, and 900 cycles. The
relay should go to lockout after the fourth trip.
Reclosing Relay States Test
Purpose:
Verify reclosing relay states (
79RS
,
79CY
,
79LO
).
Method:
1. Enter the settings in
Reclosing Relay Tests Setup
if you haven't already.
You can observe the reclosing relay states while performing the preceding
Reclosing Relay Open Interval Timer Test
.
2. When you first trip the circuit breaker simulator while in the reset state, the front
panel RS (reset) LED extinguishes and the A1 output contact deasserts (A1 =
79RS
). The reclosing relay is no longer in the reset state. The A2 output contact
asserts (A2 =
79CY
), and the reclosing relay is in the reclose cycle state. The
reclosing relay remains in the reclose cycle state until one of the following
occurs:
The circuit breaker remains closed throughout the reset interval time
(79RST = 1800 cycles) so the reclosing relay goes to the reset state. The
front panel RS (reset) LED illuminates, the A1 output contact asserts
(A1 =
79RS
), and the A2 output contact deasserts (A2 =
79CY
).
or
All open intervals are exhausted and the circuit breaker remains open, so
the reclosing relay goes to the lockout state. The front panel LO
(lockout) LED illuminates, the A3 output contact asserts (A3 =
79LO
),
and the A2 output contact deasserts (A2 =
79CY
).