ABB RELION 620 Series Technical Manual page 764

Section 9
Control functions
758
GUID-FA8ADA22-6A90-4637-AA1C-714B1D0DD2CF V2 EN
Figure 387: Determination of the checking time for closing
The control module receives information about the circuit breaker status and thus is able
to adjust the command signal to be delivered to the Synchro check function. If the external
command signal CL_COMMAND is kept active longer than necessary, the
CMD_FAIL_AL alarm output is activated. The alarm indicates that the control module has
not removed the external command signal after the closing operation. To avoid
unnecessary alarms, the duration of the command signal should be set in such a way that
the maximum length of the signal is always below Maximum Syn time + 5s.
Maximum Syn time
GUID-4DF3366D-33B9-48B5-8EB4-692D98016753 V2 EN
Figure 388: Determination of the alarm limit for a still-active command signal
Maximum Syn time
Close pulse
5s
1MAC504801-IB E
620 series ANSI
Technical Manual