ABB RELION 620 Series Technical Manual page 758

Section 9
Control functions
9.3.3
9.3.4
752
Functionality
The synchrocheck function 25 checks the condition across the circuit breaker from
separate power system parts and gives the permission to close the circuit breaker. 25
includes the functionality of synchrocheck and energizing check.
Asynchronous operation mode is provided for asynchronously running systems. The main
purpose of the asynchronous operation mode is to provide a controlled closing of circuit
breakers when two asynchronous systems are connected.
The synchrocheck operation mode checks that the voltages on both sides of the circuit
breaker are perfectly synchronized. It is used to perform a controlled reconnection of two
systems which are divided after islanding and it is also used to perform a controlled
reconnection of the system after reclosing.
The energizing check function checks that at least one side is dead to ensure that closing
can be done safely.
The function contains a blocking functionality. It is possible to block function outputs and
timers if desired.
Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
SECRSYN has two parallel functionalities, the synchro check and energizing check
functionality. The operation of the synchronism and energizing check functionality can be
described using a module diagram. All the modules in the diagram are explained in the
next sections.
GUID-72E99872-C94E-4B9F-9EF8-C479C8ED8F6B V2 EN
Figure 382: Functional module diagram
Energizing
check
Synchro
check
1MAC504801-IB E
620 series ANSI
Technical Manual