InteliLite Global Guide
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Image 5.18 Breaker control outputs
MCB special requirements
If a contactor is used on the MCB position, it is recommended that the wiring be provided in such a way that
the contactor will be normally closed and will open if the logical binary output MCB CLOSE/OPEN (PAGE 614)
closes. This behavior is called “negative logic” and can be adjusted by the setpoint MCB Logic (page 261).
The negative logic will prevent accidental opening of the MCB when the controller is switched off.
If a contactor is used on the MCB position, it will open itself immediately after the mains have failed,
because it will lose power for the coil. That is why the following adjustment is necessary to prevent triggering
the Wrn MCB Fail (page 699) alarm: MCB Opens On (page 263) = Mains Fail, Mains < > Voltage Delay
(page 258) ≤ 1.
If a 230 V motor driven circuit breaker is used on the MCB position and an undervoltage coil is not fitted, it is
not possible to open the breaker after the mains have failed, because there is no power for the motor drive
until the gen-set is started and providing voltage. Adjusting the setpoint MCB Opens On (page 263) = Gen
Run will prevent triggering the Wrn MCB Fail (page 699) alarm.
Breaker fail detection
Breaker fail detection is based on binary output breaker close/open comparing with binary input breaker
feedback.
IMPORTANT: It is necessary to configure breaker feedback to use this function.
IMPORTANT: Also it is possible to use breakers without feedbacks. In this case there is no check
of breaker real state.
There are three different time delays for breaker fail detection – see following diagrams.
When binary output breaker close/open is in steady state and breaker feedback is changed the breaker fail is
detected immediately (no delay).
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