Digital Mains Breaker Control - Deif Multi-line 2 Designers Reference Handbook

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The diagram shows that when the generator breaker is synchronised, the mains breaker will be
opened automatically after a time delay (t). Later the mains breaker is synchronised, and the
generator breaker is opened after the time delay (t).
The time delay is measured in seconds and can be adjusted from 0.10 to 99.90 seconds.
The same time delay is used for both generator and mains breaker synchro-
nisation.
If the function is used in a Power Management (option G5) application, then the
short time paralleling will occur between the mains breaker and the tie breaker
on the AGC mains.
The time delay typed in the set point is a maximum time. This means that if 0.10
seconds are used, the two breakers will never be closed at the same time for a
longer delay than the set point.
The short time parallel function is set up in 2700 Short time paralleling
.
The unit will normally execute the automatic mains failure sequence based on the settings
adjusted in the system setup. Besides these settings it is possible to configure a digital input that
can be used to control the mains return sequence. This input is the 'mains OK' input. The
purpose of this function is to let an external device or an operator control the mains return
sequence. The external device can e.g. be a PLC.
The flowchart below shows that if the input is configured, it needs to be deactivated in order to
initiate the mains return sequence. The load will continue on generator supply, if the input is still
activated.
The mains OK delay is not used at all when the 'mains OK' input is configured.
DEIF A/S
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Digital mains breaker control

Designer's Reference Handbook
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