6
Operation mode
indicators
When a closing command for the circuit breaker
is permitted, the synchro-check relay module
activates the closing signals of one or both of
the stages, that is, CB13 for stage 1 and CB23
for stage 2. Simultaneously, when one or both
of the closing signals are active, an yellow LED
indicator is lit in the bottom corner, to the right,
on the front panel. The indicator remains on as
long as the closing signals are active and goes
out automatically when the closing signals re-
set. At the same time the digital display on the
front panel indicates with a red digit 1 or 2
which stage has delivered the closing signal. The
operation indicator on the display goes out au-
tomatically when the stage resets. In situations,
where both stages are delivering closing signals
simultaneously, the digital display always
presents the last event, that is, the operation
indicator on the display indicates the last acti-
vated closing signal and stage.
Description of
operation mode
The closing command conditions for the cir-
cuit breaker are checked by the synchro-check
and voltage-check functions. In addition to the
closing command conditions the delivering of
the final closing signal depends on the opera-
tion mode selected for the synchro-check relay.
Selection of the operation mode depends on
whether the synchro-check relay itself directly
uses the output signal to close the circuit breaker
(command mode operation) or if another de-
vice (for example a control module) performs
the closing operation after having received a
command signal from the synchro-check relay
(continuous mode operation).
A distinctive difference between the operation
modes is that in the command mode operation
the synchro-check relay is controlled by an ex-
ternal command signal but in the continuous
mode operation no external signal is needed. In
the command mode operation the synchro-
check relay delivers the closing signal directly
to the object to be controlled (a circuit breaker)
but in the continuous mode operation the clos-
ing signal is delivered via some other equipment
which delivers the final closing signal.
The operation mode is selected separately for
the operation stages: for stage 1 with switch
SGB/3 and stage 2 with switch SGB/4.
