7-22 Maintenance and Testing Date Code 20000421
SEL-251, -2, -3 Instruction Manual
Reclosing Relay Shot Bit Test
Purpose: Verify the operation of the reclosing relay shot bit (79SH) according to the M79SH
setting.
Method: 1. Enter the settings in Reclosing Relay Tests Setup if you haven't already.
The 79SH Relay Word bit monitors any desired state of the shot counter. In this
example, it is assigned to the A4 output contact (A4 = 79SH).
This test does not require an external timer.
2. Execute the CLOSE command or energize the IN4 input (IN4 = DC; direct close)
to cause CLOSE output contact assertion. With the circuit breaker simulator
closed, IN5 is energized (IN5 = 52A) and the front panel RS (reset) LED
illuminates after the reset interval timer expires (79RST = 1800 cycles). The A1
output contact asserts (A1 = 79RS).
3. You can test the reclosing relay shot bit 79SH using Reclosing Relay Open
Interval Timer Test steps 6 through 8 without monitoring open interval times.
The number of reclosing shots (automatic reclosures) depends on the number of
set open interval times. In this example there are three open intervals, so there
are three shots. Every time the open interval timer expires, the shot counter is
incremented and an automatic reclosure is initiated (CLOSE output contact is
asserted).
When the reclosing relay is in the reset state, shot = 0. The front panel RS
(reset) LED is illuminated and the A1 output contact is asserted (A1 = 79RS).
79SH asserts according to the M79SH setting. M79SH can be set for any
combination of shots 0, 1, 2, 3, and 4. As previously mentioned, the number of
shots depends on the number of set open interval times; this example uses three
set open interval times. M79SH is set for only shot = 1 and shot = 3:
M79SH = 01010
Thus, 79SH will assert only when shot = 1 or shot = 3.
The shot = 4 position in the M79SH setting (right most position) is not
applicable in this example because there are no more than three shots.
4. Use the procedure in Reclosing Relay Open Interval Timer Test steps 6 through
8. After the first open interval expires, the shot counter increments (shot counter
increments from shot = 0 to shot = 1) and the CLOSE output contact is then
asserted. Because of the M79SH setting (M79SH = 01010), the A4 output
contact also asserts (A4 = 79SH). The shot counter remains at shot = 1 and the
A4 output contact remains asserted until:
The circuit breaker remains closed throughout 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), the A2 output contact deasserts (A2 = 79CY), the shot counter
To Next Page
