Rated Operating Sequence

It will work just fine.

The listed operating sequence gives the minimum time between trip and close operations that the breaker will withstand its rated interrupting and thermal limits. This is needed if you are programming reclosing relays, so that after an initial fault interruption (the first O), you must wait at least 0.3 seconds to reclose. If the fault still remains and the breaker trips again (close - open, CO), you must then wait at least 1 minute before trying to reclose a second time into a possible fault if you expect the breaker to withstand it. If you wait 3 minutes instead of just 1 minute, the breaker will have had additional time for the conductors to cool down from the thermal stress of the first reclose and retrip.

Thanks PeterT,

What I'm understanding that we need to set the auto reclosing relay on 3min no matter CB operating sequence O-0.3s-CO-1min-CO or O-0.3s-CO-3min-CO.

>As a result the CB will be ready for reclose and retrip 2min before signal from reclosing relay trigger.

What happen that the client request same as existing system for CB operating sequence?

Are we need to tell the manufacturer to change or only setting time inside the CB control circuit (if provided)

Your assistance appreciated

I think ,change in the CB operating sequence would involve change in the design of the CB itself, because the former one will have to face more arduous duty .

The CB manufacturer will be in a better position to answer.

The circuit breaker's rated operating sequence is the limit of what the breaker is capable of doing. You can set the reclosing sequence to anything you need for your electrical system, as long as you do not exceed the breaker's capabilities. So if your sequence calls for 15 second 1st reclose, then 30 second 2nd reclose, you cannot do that because the 2nd is faster then the breaker can recover. However, a 15 second 1st reclose, then a 60 second (or longer) 2nd reclose is possible within the ratings. If you have more questions, as another poster mentioned, talk to the breaker manufacturer.