400a Supply needed

DJF84 · Jul 1, 2016

Morning Guys

just after a bit of guidance if possible regarding a new supply that is needed.

we will be installing some equipment that requires a 400A 3 phase supply, the Clients LV panel is old gaining a 400a supply from this is proving difficult.

Its has a number if spare ways which will only accommodate MCCB's up to 250A, of which these we can obtain.

My question is can we supply the new equipment from 2 separate 200/250A MCCB's within the LV panel? A parellel feed but separate breakers?

Your help is is very much appreciated.

thanks
Dan

Leesparkykent · Jul 1, 2016

DJF84 said:
Morning Guys

just after a bit of guidance if possible regarding a new supply that is needed.

we will be installing some equipment that requires a 400A 3 phase supply, the Clients LV panel is old gaining a 400a supply from this is proving difficult.

Its has a number if spare ways which will only accommodate MCCB's up to 250A, of which these we can obtain.

My question is can we supply the new equipment from 2 separate 200/250A MCCB's within the LV panel? A parellel feed but separate breakers?

Your help is is very much appreciated.

thanks
Dan

Does the new equipment need a 400A per phase?

DJF84 · Jul 1, 2016

Hi Lee

Yes I will be around 400a per phase

Regards

Leesparkykent · Jul 1, 2016

DJF84 said:
Hi Lee

Yes I will be around 400a per phase

Regards

Big bit of kit then. could you not install a busbar chamber and switch fuse/fused switch?

Darkwood · Jul 1, 2016

Without knowing the nature of the load(s) then suggestions are edging on the guessing here, is this for one load, if so is it inductive, are there multiple circuits etc, you get my drift.

jackhammerJIM · Jul 1, 2016

DJF84 said:
Morning Guys

My question is can we supply the new equipment from 2 separate 200/250A MCCB's within the LV panel? A parellel feed but separate breakers?

Your help is is very much appreciated.

thanks
Dan

No you cannot use 2 separate mccbs for the supply . A parallel supply would be 2 lots of cables fed from the same mccb.

DJF84 · Jul 1, 2016

Lee - yes that was our 2nd option really, we would need to pull the existing 240mm SWA out and reinstall into a buzz bar somewhere with limited room, would also need a longer shut down which we were trying to avoid. This maybe our only option but just thought would see other views really.

It is a 250kw solar PV system, the supply will be to the solar PVDB which has a 400a main switch controlling 8 MCB's individually controlling the inverters.

Cheers guys

Darkwood · Jul 1, 2016

jackhammerJIM said:
No you cannot use 2 separate mccbs for the supply . A parallel supply would be 2 lots of cables fed from the same mccb.

Yes it is possible but careful design is needed, how about a 400amp MCCB with volts free release that is fed from two 250mp MCCB's, the 2 x 250amp have a control circuit holding the MCCB volts free release on the 400amp. The 400amp then feeds the 2 parallel cables. If either 250amp was to trip then it would drop out the 400amp thus cutting all power to parallel cables.
This although not conventional in method would allow for the use of existing ways to deliver the power required.

There is never a 'no you cannot' in my book until I have exhausted all options. :smart:

Leesparkykent · Jul 1, 2016

Even though longer shutdown etc I would still go down this route rather than some Heath Robinson set up. Surely this should of been picked up whilst being surveyed and discussed with the client?

DJF84 · Jul 1, 2016

Thanks for the replies guys it is much appreciated. During survey the panel in question did have a spare way dutiable for a 400A MCCB, this has now been taken up and all other ways are only capable to house the 250A MCCB's as the spacing between the buzz bars are slightly smaller. Just one of those things but now we just need to find a way around it.

The other option was to connect directly in the bottom of the main switch of the LV panel but sadly it not a lug connection. We would bee to find som sort of pin which could go into the terninal and then allow for 2 X lugs to be mounted on. I have done a lot of searching today and cannot seem to find anything like what we require. If we could do this it would then just be a case of mounting a switch fuse adj the panel.

rgards

jackhammerJIM · Jul 1, 2016

Thinking out of the box there dark wood . i would scour the regs to see if anything prohibits but i take your word it complies :cool3:

A 250 kw pv system does not require 400 amp per phase ?????????

my bad . 360 amps per phase

Leesparkykent · Jul 1, 2016

jackhammerJIM said:
Thinking out of the box there dark wood . i would scour the regs to see if anything prohibits but i take your word it complies :cool3:

A 250 kw pv system does not require 400 amp per phase ?????????

my bad . 360 amps per phase

I was just quoting you but computer died lol

UKMeterman · Jul 1, 2016

This is a big bit of kit, have you tried giving the technical departments of Siemens, Schinider and MEM a call, there may be modern automated versions that can be used in conjunction with the required mains failure relay.