ABB SPAU 140 C User Manual And Technical Description page 17

Miniature circuit-
breakers of the
voltage measuring
circuits
Supervision of the condition of the relay's ex-
ternal measuring circuit is not incorporated in
the synchro-check relay. Should the external
measuring circuit of some reason be damaged,
malfunction may follow, and based on the volt-
age measured, the relay then considers the line/
busbar to be dead, although it actually is ener-
gized. In consequence, a voltage-check is made,
and, if the energizing direction corresponds to
the relay setting, a close permission/command
is given. Then the close operation is made
against a live section without the synchronism
being checked, as the energizing conditions were
considered to be fulfilled. For this reason it is
important that the safety switch of the measur-
ing circuit, when operating, provides the
synchro-check relay with a blocking signal that
prevents circuit breaker closing. When the re-
lay is commissioned, it should be checked that
the blocking function operates correctly and that
the configuration of the blocking signals (SGB
switchgroup) is in order. The states of the indi-
vidual blocking signals can be checked in the
first submenu of register 0.
The miniature circuit-breakers of the measur-
ing circuit and the blocking function can be
tested as follows.
- Enable blocking of the stages by selecting the
checksum 3 for the switchgroup SGB. Then
stage 1 is blocked by the signal BS13 and stage
2 by the signal BS23.
- Configure switchgroup SGF so that the check-
sum is 136. Then the stages operate when the
operate time t expires. Stage 1 activates the
vc
output signal CB13 and stage 2 the output
signal CB23. The blocking function should
operate so that an activated output signal re-
sets, when the blocking input of the stage is
activated; the blocking signal BS13 resets the
output CB13 and the blocking signal BS23
resets the output CB23. When the blocking
has been eliminated, the output returns to its
active state.
Alternatively, the test can be carried out so that
switchgroup SGB is given the checksum value
3 and switchgroup SGF the checksum value 0
and then the blocking signals to the stages are
activated. The next step is to give switchgroup
SGF the checksum value 136, which enables
the voltage-check function of both stages. After
the setting value has been changed the output
signal of neither stage is allowed to activate. Fi-
nally, the blocking of the stages is eliminated
and then the output signal has to be activated
when the preset operate time expires.
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