ABB Relion 670 series - Page 768

• The line 1 voltage is selected if the line 1 disconnector is closed.
• The bus 1 voltage is selected if the line 1 disconnector is open and the bus 1 circuit breaker is
closed.
• The line 2 voltage is selected if the line 2 disconnector is closed.
• The bus 2 voltage is selected if the line 2 disconnector is open and the bus 2 circuit breaker is
closed.
The function also checks the fuse-failure signals for bus 1, bus 2, line 1 and line 2. If a VT failure is
detected in the selected voltage an output signal VSELFAIL is set. This output signal is true if the
selected bus or line voltages have a MCB trip. This output as well as the function can be blocked
with the input signal BLOCK. The function block diagram for the voltage selection of a bus circuit
breaker is shown in figure
405 and for the tie circuit breaker in figure 406.
AND
AND
OR
OR
VL1FF
VL1OK
VB1FF
VB1OK
VB2FF
VB2OK
BUS1_CL
BUS1_OP
LINE1_CL
LINE1_OP
BLOCK
L1SEL
AND
AND
VSELFAIL
VL2FF
VL2OK
OR
AND
AND
BUS2_CL
BUS2_OP
LINE2_CL
LINE2_OP
AND
AND
L2SEL
OR
AND
B2SEL
AND
AND
AND
en05000780_2_ansi.vsd
OR
OR
line2Voltage
bus2Voltage
line1Voltage
invalidSelection
lineVoltage
selectedFuseOK
ANSI05000780 V2 EN-US
Figure 405: Simplified logic diagram for the voltage selection function for a bus circuit breaker in a breaker-
and-a-half arrangement
Section 14 1MRK 502 066-UUS B
Control
762
Technical manual