ABB REG670 - Page 645

The function checks the fuse-failure signals for bus 1, bus 2 and line voltage
transformers. Inputs UB1OK-UB1FF supervise the MCB for Bus 1 and UB2OK-
UB2FF supervises the MCB for Bus 2. ULN1OK and ULN1FF supervises the MCB
for the Line voltage transformer. The inputs fail (FF) or healthy (OK) can alternatively
be used dependent on the available signal. If a VT failure is detected in the selected
voltage source an output signal USELFAIL is set. This output signal is true if the
selected bus or line voltages have a VT failure. This output as well as the function can
be blocked with the input signal BLOCK. The function logic diagram is shown in
figure
302.
AND
AND
AND
bus1Voltage
OR
OR
OR
ULN1FF
ULN1OK
UB1FF
UB1OK
UB2FF
UB2OK
B2QCLD
B2QOPEN
B1QCLD
B1QOPEN
BLOCK
bus2Voltage
AND
1
B2SEL
B1SEL
AND
AND
AND
USELFAIL
en05000779-2.vsd
OR
invalidSelection
busVoltage
selectedFuseOK
IEC05000779 V2 EN
Figure 302: Logic diagram for the voltage selection function of a single circuit breaker with double busbars
Voltage selection for a 1 1/2 circuit breaker arrangement
Note that with 1½ breaker schemes three Synchrocheck functions must be used for the
complete diameter. Below, the scheme for one Bus breaker and the Tie breaker is
described.
With the setting parameter CBConfig the selection of actual CB location in the 1 1/2
circuit breaker switchgear is done. The settings are: 1 1/2 Bus CB, 1 1/2 alt. Bus CB or
Tie CB.
1MRK502052-UEN B Section 14
Control
639
Technical manual