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SCHNEIDER NEW TYPE MCCBs

John Peckham

Good afternoon All.

I used to be able to call up Schneider Technical and speak directly with one of their technical team and have a 2 way technical conversation and get sound technical advice. Now you cannot do that. If you call now a helpful lady says she will pass you enquiry to technical. I wanted information on the new type Compact MCCBs for a design I am doing. Their response was to send me a  a long technical document for me to wade through and try and find the information I wanted.

I wanted to know if the new Type Compact T NSX MCCBs  and the NSXm can be fitted in to the existing Powerpact 4 panel boards. Also what is the difference between a Micrologic Type 2.2A and a 2.2AB trip unit? I have worked out the Type G is for generators and the Type M is for motors (I think)?

Also the trip units now have a "Reflex " function which can be turned on and off , what does this do?

I have emailed the questions to Schneider but in the meantime can anyone on the forum help?

Thanks

JP

JP

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  • 0

    Ah, so it's the function that introduces a deliberate arc for a short duration after a fault is detected - to limit the magnitude of the fault current (so downstream devices aren't over-stressed) and gives time for downstream devices to clear the fault, if the downstream devices clear the fault is re-closes, if not it opens properly and disconnects.

    I wonder what downstream AFDDs will think of the resulting current signature flowing through them to their loads?

       - Andy.

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  • 0

    Ah, so it's the function that introduces a deliberate arc for a short duration after a fault is detected - to limit the magnitude of the fault current (so downstream devices aren't over-stressed) and gives time for downstream devices to clear the fault, if the downstream devices clear the fault is re-closes, if not it opens properly and disconnects.

    I wonder what downstream AFDDs will think of the resulting current signature flowing through them to their loads?

       - Andy.

Children
  • 0 in reply to AJJewsbury

    Well, all mechanical breakers introduce an arc while tripping, just the simple ones become more or less constant speed at fault currents beyond a certain level. 

    Here, a more explosive arc actually means the contacts get separated faster - a lot faster, no waiting around with fault currents flowing for the next mains zero-crossing with these devices..The arc duration is significantly curtailed.

    As to the arc fault breaker question - who knows ?  I'd hope that at least the better ones only respond to things that repeat over a few mains cycles but as it is all shrouded in mystery we will never be sure.

    Mike.

  • 0 in reply to mapj1

    Here, a more explosive arc actually means the contacts get separated faster

    On second reading, you're quite correct. I was confusing it with a different feature in some MCCBs where the contact open a little before de-latching, to produce an arc to limit the fault current while allowing downstream devices time to trip while still limiting energy let-through - i.e. in effect a delayed trip. So quite the reverse of this one. Case of seeing what I expected to see rather than what was actually written Zipper mouth

       - Andy.

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