ABB RELION REX640 Technical Manual page 1401

1MRS759142 C
REX640
Technical Manual
A
U_Bus
SECRSYN
DARREC
GUID-75677206-2CCD-4465-973F-C75F20AEA241 V1 EN
Figure 747: Synchrocheck function SECRSYN checking energizing conditions
and synchronism
Connections
A special attention is paid to the connection of the protection relay. Furthermore it is
checked that the primary side wiring is correct.
A faulty wiring of the voltage inputs of the protection relay 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 protection relay
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 protection relay is consistent regarding the energizing inputs U_BUS
(bus voltage) and U_LINE (line voltage).
The wiring should be verified by checking the reading of the phase difference
measured between the U_BUS and U_LINE voltages. The phase difference measured
by the protection relay has to be close to zero within the permitted accuracy tolerances.
The measured phase differences are indicated in the LHMI. At the same time, it is
recommended to check the voltage difference and the frequency differences presented
in the monitored data view. These values should be within the permitted tolerances,
that is, close to zero.
Figure 748 shows an example where the synchrocheck is used for the circuit breaker
closing between a busbar and a line. The phase-to-phase voltages are measured from
the busbar and also one phase-to-phase voltage from the line is measured.
U_Line U_Line
Section 9
Control functions
G
B
U_Bus
SECRSYN
PLC
1395