SCHNEIDER NEW TYPE MCCBs

Hi John. The MCCBs fit the busbars, provided that they have shear-off connection bolts. The 2.2AB trip unit has the Reflex feature, which adds the automatic reset function to the usual 2.2 thermal and magnetic settings.

Common misconception on the Reflex function. Here is a link with an article put together by ElectricalOM. It has clear details on the new range. And contains a link to an FAQ from the manufacturer.

electricalom.com/.../knowledgebase.php

Hope it helps

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.

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.

Thanks for all the input and a Special thanks to Spencer for the comprehensive explanation.

The function may not be adjustable but you can switch it on and off.

JP

EOM have been in to this with Schneider, I can assure you there is no switch to turn on and off the Reflex it is a physical part of the operation of the device.

We will get another meeting set up with the Schneider team and will reconfirm. I will post up the outcome

There is on my software to turn it off or on but the current is fixed.

JP

I see the issue, and why now so many have had the same misunderstanding. Hence the ElectricalOM article on the issue.

In the manufacturer data shows no such ability. The information on this was confirmed with Schneider prior to the article being published.

The only conclusion I can offer to you is your software is wrong.

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

   - Andy.

Afternoon All

Just to let you know I had an email back from Schneider  to tell me that the Micrologic Type AB MCCBs are for where the MCCB is used as an incomer connected to a supply and the Type A is for use within and installation.

JP