ABB 615 Series ANSI, Technical Manual

Page: 532 / 713

1MAC050144-MB C
Section 7
Control functions
615 series ANSI 525
Technical Manual
Network and the generator running in parallel with the network are connected through the
line AB. When a fault occurs between A and B, the IED protection opens the circuit
breakers A and B, thus isolating the faulty section from the network and making the arc
that caused the fault extinguish. The first attempt to recover is a delayed autoreclosure
made a few seconds later. Then, the autoreclose function DARREC gives a command
signal to the synchrocheck function to close the circuit breaker A. 25 performs an
energizing check, as the line AB is de-energized (V_BUS>
Live bus value , V_LINE<
Dead line value ). After verifying the line AB is dead and the energizing direction is
correct, the IED energizes the line (V_BUS -> V_LINE) by closing the circuit breaker A.
The PLC of the power plant discovers that the line has been energized and sends a signal
to the other synchrocheck function to close the circuit breaker B. Since both sides of the
circuit breaker B are live (V_BUS >
Live bus value , V_LINE > Live bus value ), the
synchrocheck function controlling the circuit breaker B performs a synchrocheck and, if
the network and the generator are in synchronism, closes the circuit breaker.
.
Figure 289: Synchrocheck function 25 checking energizing conditions and
synchronism
Connections
A special attention is paid to the connection of the relay. Further, it is checked that the
primary side wiring is correct.
A faulty wiring of the voltage inputs of the IED causes a malfunction in the synchrocheck
function. If the wires of an energizing input have changed places, the polarity of the input
voltage is reversed (180°). In this case, the IED permits the circuit breaker closing in a
situation where the voltages are in opposite phases. This can damage the electrical devices
in the primary circuit. Therefore, it is extremely important that the wiring from the voltage
transformers to the terminals on the rear of the IED is consistent regarding the energizing
inputs V_BUS (bus voltage) and V_LINE (line voltage).
G
25
79
25
PLC
A
B
V_Bus V_Bus V_Line V_Line