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 (I>>). 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 (I>) and the low stage of the non-directional earth-
fault protection (Io>). It has the same reclosing 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 I>
or Io>, is set as a delayed autoreclosing and executed after an unsuccessful
high-speed autoreclosing of a corresponding sequence.
Figure 554: Autoreclosing 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 I>> protection stage to clear the fault
t
l>
or
lo>
Operating time for the I> or Io> 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
1MRS757644 H Control functions
620 series
Technical Manual
1035
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