AGC Designer’s Reference Handbook
DEIF A/S Page 69 of 168
Breaker spring load time
If the breaker needs time to reload the spring after it has opened, then the AGC can take this
delay into account. This can be controlled through timers in the AGC or through digital
feedbacks from the breaker, depending on the breaker type.
Principle
The diagram shows an example where a single AGC in island mode is controlled by the AUTO
start/stop input.
This is what happens: When the AUTO start/stop input deactivates, the GB opens. The AUTO
start/stop is reactivated immediately after the GB has opened, e.g. by the operator through a
switch in the switchboard. However, the AGC waits a while before it issues the close signal
again, because the spring load time must expire (or the digital input must be activated - not
shown in this example). Then the AGC issues the close signal.
Digital input
This can be used e.g. when the breaker is able to send a feedback to the AGC when its spring is
reloaded.
There is one input for the generator breaker and one for the mains breaker. The input
configuration is done through the PC utility software. The names of the inputs are ‘GB spring
loaded’ and ‘MB spring loaded’. In the example below they are configured to terminal 91 and 92.
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