ABB Relion Technical Manual page 364

Section 12
Control
358
the selected Line voltage as a reference to the fixed Bus 1 voltage, which indicates
B1SEL.
The fuse supervision is connected to VL1OK-VL1FF, VL2OK-VL2FF and with
alternative Healthy or Failing MCB signals depending on what is available from each
MCB.
The tie circuit breaker is connected either to bus 1 or line 1 voltage on one side and the
other side is connected either to bus 2 or line 2 voltage. Four different output combinations
are possible, bus to bus, bus to line, line to bus and line to line.
• 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
breaker in figure 168.
1MRK 502 048-UUS A
167 and for the tie circuit
Technical manual