Section 5 1MAC309294-MB F
Control functions
312 RER620
Technical Manual
Example 2
There are two separate sequences implemented with three shots. Shot 1 is implemented by
CBB1 and it is initiated with the high stage of the overcurrent protection (50P-1). Shot 1
is set as a high-speed autoreclosing with a short time delay. Shot 2 is implemented with
CBB2 and meant to be the first shot of the autoreclose sequence initiated by the low stage
of the overcurrent protection (51P) and the low stage of the non-directional ground-fault
protection (51N/G). It has the same reclose time in both situations. It is set as a high-speed
autoreclosing for corresponding faults. The third shot, which is the second shot in the
autoreclose sequence initiated by 51P or 51N/G, is set as a delayed autoreclosing and
executed after an unsuccessful high-speed autoreclosing of a corresponding sequence.
Figure 164: Autoreclose sequence with two shots with different shot settings
according to initiation signal
t
HSAR
Time delay of high-speed autoreclosing, here:
First reclose time
t
DAR
Time delay of delayed autoreclosing, here:
Second reclose time
t
l>>
Operating time for the 50P-1 protection stage to clear the fault
t
l>
or
lo>
Operating time for the 51P or 51N/G protection stage to clear the fault
t
CB_O
Operating time for opening the circuit breaker
t
CB_C
Operating time for closing the circuit breaker
In this case, the number of needed CBBs is three, that is, the first shot's reclosing time
depends on the initiation signal. The CBB sequence is as follows:
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