DC application

[Ayman_sadek]

i want to use nsx100f 4x100A 4p4d circuit breaker in a DC Application, my system voltage is 48v, 100A DC will pass through each pole of the breaker, i will use two of them one for positive and the other for negative pole. Do this circuit breaker works properly in such situation 

[RHH · Accepted solution]

Dear @Ayman_sadek ,

I suggest you use the specific DC NSX found here; NSX for DC 
And use a TM100 DC trip unit with it.

Therefor I cannot tell you the DC specifics of a non DC NSX, as its probably not tested for it.

The standard NSX100F states; 

network type

AC

Hope this helps you out.

[Ayman_sadek]

Dear @RHH ,

thanks for ur reply, but what makes me confused that i found the following in FAQ schnieder and that was the reply 

(CAN NSX AC BREAKER be USED IN DC APPLICATIONS ?

ONLY the following 2 categories of the compact NSX AC MCCB are proven to operate under DC rated operatinal voltage as shown in the attached catalogue Panorama.
1- The compact NSX AC MCCB 1 Pole - from 100 to 250A only - can be used under 250VDC rated operational voltage .
2- The compact NSX AC MCCB 2 Poles - from 100 to 250A only - can be used under 500VDC rated operational voltage.
Kindly use the below link to download the Schneider offer for DC networks Circuit breakers from 16 to 4000A Compact NSX DC & Masterpact NW DC.
https://www.se.com/uk/en/download/document/LVPED)

thats why iam asking if i can use NSX AC type on my application since in our country the NSX DC is not available 

regards 

[Berkhof]

Hi Ayman,

I think the FAQ refers to the 1P and 2P NSX. This one is for both AC and DC.

The frame is really meant for AC. There is a Micrologic that can be used in both an AC and a DC NSX, The TM-G. 

But I don't recommend using AC components for DC.

Kind regards,

John

[Christian_Bach]

Hi @Ayman_sadek ,

First, very important point, never use a circuit breaker for performances that are not claimed on the catalog, you would not be covered by the manufacturer and authorities in case of issue, on top of potential safety risks of course.

Second, @Berkhof , a Micrologic shall NOT be used in DC, the current sensors DO NOT work at all !

I think for your application a 2P NSX might be ok.

Christian

[Berkhof]

Hi @Christian_Bach,

According to the Schneider documentation, the TM-G is suitable for both AC and DC.

https://www.se.com/ww/en/product/C164MG125/trip-unit-tm125g-compact-nsx160-4-poles-4d-neutral-fully-...

Maybe I shouldn't have called it a Micrologic but a Trip unit 😉

Kind regards,

John

[Christian_Bach]

Hi @Berkhof ,

Thanks for your inputs. TMD or TMG are thermal magnetic trip units. TMG have double AC DC markings, you are right, but it must be used with a DC breaking block in this case.

And sorry if my previous statement was a bit "rude", it was just to make crystal clear that Micrologic are not working is DC and thus avoid misuse 😉.

This is Schneider vocabulary, Micrologic wording applies to electronic protection only.

Thanks,

Christian