Application Example 1 - ABB SPAU 140 C User Manual And Technical Description

Application
example 1
The network and the generator running in par-
allel with the network are connected together
through the line AB. When a fault occurs be-
tween A and B the relay 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 at-
tempt to recover is a delayed auto-reclosure
made a few seconds later. Then the auto-reclose
relay gives a command signal to the synchro-
check relay to close the circuit breaker A. The
synchro-check relay SPAU 140 C performs a
voltage check, as the line AB is deenergized
U1
SPAU 140 C
Auto-reclosure
relay
Fig. 4. Synchro-check relay SPAU 140 C checking energizing conditions and synchronism.
(U1>U
line AB is dead and that the energizing direc-
tion is correct, the relay energizes the line (U1 -
> U3) by closing circuit breaker A. Then the
PLC of the power plant discovers that the line
has been energized and sends a signal to the
other synchro-check relay to close circuit breaker
B. Since both sides of circuit breaker B are live
(U1 > U
relay controlling circuit breaker B performs a
synchro-check and, if the network and the gen-
erator are in synchronism, closes the circuit
breaker.
A
U3
, U3< U ). After verifying that the
max min
, U3 > U ), the synchro-check
max max
B
U3 U1
SPAU 140 C
PLC
9