Operating instructions
7SV512
V1
C53000---G1176---C91
104
6.7.4 Checking the intertrip to the op-
posite feeder end
All devices which are necessary for transmission of
the intertrip signal to the opposite feeder end must
be commissioned in accordance with the asso-
ciated commissioning instructions. The transmis-
sion link must be checked.
The trip commands to the bus-bar circuit breakers
remain ineffective during the test. The disconnec-
tors at both sides of the feeder circuit breaker must
be open. The circuit breaker is closed.
At the remote end of the feeder, the circuit breaker
must be isolated from the feeder and the bus-bar,
too. The circuit breaker is closed there.
Anyone of the tests as described in Section 6.7.2 is
repeated. The initiation conditions remain effective
after the local feeder breaker has tripped.
After expiry of the time T2---CB---AUX (address 1213)
the intertrip signal is transmitted and the circuit
breaker of the opposite feeder end is tripped. It is
possible that trip of the remote end breaker is made
dependent of further conditions: this must be con-
sidered. When assessing the time delay it must be
taken into account that this delay depends on the
parameter T---TRIP---BB (address 1211): it may be
started either with initiation or after the local trip com-
mand of the breaker failure protection.
If the intertrip check is to be carried out with current
flow as breaker failure criterion (e.g. because the
auxiliary contact criterion is not used), then either
the feeder must be energized at both ends in order
to produce a current above the pick-up value I---BF
(address 1202), or a corresponding secondary cur-
rent must be injected into the relay under test. In the
first case, it must be ensured that a back-up protec-
tion for the feeder is effective in case a real fault
would occur during the test.
6.7.5 Checking the bus-bar trip
The distribution of the trip commands to the adja-
cent circuit breakers of the bus-bar depends widely
on the bus-bar arrangement.
Checking the bus-bar trip should be carried out after
completion of the tests on all individual feeder circuit
breakers.
In most cases a trip bus is installed for the trip com-
mands of the bus-bar breakers. This trip bus is ener-
gized by the trip relay 1 of each breaker failure pro-
tection relay (command function
”BFP Trip BB”
,
FNo 507), if applicable, dependent of the position of
the bus-bar disconnector(s) of the feeder under test.
The important thing is that the bus-bar trip com-
mand arrives at all circuit breakers associated with
that bus-bar section, to which the feeder of the origi-
nating protection relay is connected, including any
bus tie, and that the bus-bar trip command does not
arrive at any of the other circuit breakers. The bus-
bar trip checks must be performed such, that finally
all switching combinations have been covered.
After completion of the tests, it must be carefully
checked that the required operational status of the
trip bus(ses) is re-arranged (e.g. in case that certain
circuits have been interrupted for certain tests) and
that all control voltages are switched on (in case cer-
tain control voltages have been switched off for cer-
tain tests). This is also valid for all the tripping com-
mands of feeder protection relays which have been
interrupted in order to simulate a breaker failure con-
dition.
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