ABB Relion 670 series, Technical Reference Manual

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The fuse supervision is connected to VLNOK-VLNFF and with alternative Healthy or
Failing fuse signals depending on what is available from each fuse (MCB).
The tie circuit breaker is connected either to bus 1 or line 1 on one side and the other
side is connected either to bus 2 or line 2. 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
fuse-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 fuse failure. 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
312
and for the tie circuit breaker in figure 313 .
1MRK505222-UUS C
Section 12
Control
623
Technical reference manual