63A 3 phase socket

[apprentice87]

4mm would be fine, 6mm would be great, and 10mm would be even better, for current rating and VD purposes with that load and run length. BUT, i suspect it will all come down to R1 + R2 in the end..

Just remember, does the charger have a great big transformer in it?? What MCB will you need,, A "B" or a "C" or even a "D"..

This will be the deciding factor i suspect. not the load or anything else, so as a first move i would be asking the makers what sort of OCPD they recommend..

Completely forget the load, it is the OCPD chosen that you have to design your cable around..

Another thing, earthing type??

john..

 

[Tony S]

OK, customer reports that it is 23kW total load, so I make that about 42Amps total or 16A per phase, so we would be happy on a 20A MCB and a 20A commando socket with a 10mm 4 core XLPE SWA rated at 73A, 6mm is rated at 53A according to the big yellow book, so a l ittle undersized  though it would probably work fine!

I’m not quite sure how you are working that out but I get 33.2A per phase at a PF of 1.

What is the load, if it’s inductive then the current will rise.

 

[binky]

pinched amps from Doncaster cables calculator - per phase not total, my bad! Please ignore the rest of that post it's garbage! 

 

[Risteard]

OK, customer reports that it is 23kW total load, so I make that about 42Amps total or 16A per phase

Ignoring power factor it's about 33.2A per phase.

Oops... sorry - I see Tony has already pointed this out.

 

[Andy™]

33.2a. would need a 63a socket. you cant get them in 20a either, its 16, 32, 63 or 125 (larger is available iirc, but not used very often)

 

[Tony S]

If you’re being pedantic.

 

[binky]

installed 63A socket with interlock

Ignoring power factor it's about 33.2A per phase.

Oops... sorry - I see Tony has already pointed this out.

think I'm going to ignore the Doncaster cable calculator in future....at least for ampage, I'm kind of guessing they apply a worst case scenario, altough the option for clipped direct was selected

 

[apprentice87]

I would DEFINITELY use a 32A plug and socket myself, if for no better reason that the gland thing on the rear end of the plug, will be designed to grip cable about an inch in diameter, and i doubt to be honest, whether it would even be suitable for what will, presumably, be 4mm flex from the charger..

I have welders with 63a plugs on them and they are great big unwieldy clumps things.. [the plugs, not the welders!!]

john..

 

[binky]

Used 10mm 4core XLPE SWA, the cabe calculator seemed to think either 4mm or 6mm would be fine, depending on the cable type, for the length of run. 

 

[apprentice87]

Bigger the better.. i would have liked to use a bigger cable than 4 or 6mm to be honest..

Does the punter still want the 63A MCB then??

john..

 

[Risteard]

I would DEFINITELY use a 32A plug and socket myself

The load exceeds 32A though. (33.2A+)

 

[apprentice87]

Yes, but if it is a charger, i cannot see that it pulls this load all the time, and it is only a slight overload. Not ideal i grant you.. I would want to see the charger myself and see what the makers say. If the punter insists that he wants a 63A supply though, that is what he should get...

john..

 

[Sidney]

I would more than likely be going with 32 amp socket with a 32 amp OCPD. Although we should be using the declared nominal voltage of 400v this calculation throws us slightly over the 32 amp rating of the socket.

If we use a more realistic 415v then the load will be 31.99 amps. Caveat being that voltage is actually measured on site to confirm it is suitable. 

I would then have to consult the manufacturers instructions but at a guess this would be a resistive load, possibly a bridge rectifier, so potentially a B curve MCB of Gg fuse. As this is a modern charger I would hazard a guess that it would more than likely be a soft start but only the manufacturer can confirm.

What cable installation method is to be used?

I would also need to know supply characteristics and expected Ze for the installation and also any applicable Zdb and voltage drop. Only then can I select my cable.

A lot of people tend to forget to account for volt drop when using distribution circuits, I've only recently started placing a calculated volt drop note on the DB circuit chart, I would use a label but this would only annoy Tony...

 

[Tony S]

I think we’ve been looking at this as a purely resistive load, I know I have. As this charger is liable to be inductive and therefore a lagging PF. The PF will increase the current draw. I’ve worked some figures out but they are pure guesswork.

I think in this case it’s “go by the manufacturers instructions”.

It would be interesting to see a photo of the rating plate.

 

[Sharpend]

@Sidney nice to see the 2396 wasn’t wasted  

 

[Sidney]

@Sidney nice to see the 2396 wasn’t wasted  

It was, I've forgotten most of it and will probably have to resit my 18th edition test several times...  :slap

 

[binky]

Bigger the better.. i would have liked to use a bigger cable than 4 or 6mm to be honest..

Does the punter still want the 63A MCB then??

john..

Yep, I was going to put a 50A in, but he wants full spec capability of the socket - lord knows why.

 

[Sidney]

Yep, I was going to put a 50A in, but he wants full spec capability of the socket - lord knows why.

What does the manufacturer state?

 

[binky]

now idea, nit sen the spec sheet. Trouble with customer is he has degree in electrical engineering or something like that. Very intelligent but clueless  :^O . Tried to get me to connect to a differnt dis board, another 50m with only 4 hours on a saturday morning to complete works and it easn't an easy run!

 

[Sidney]

Contact the manufacturers for guidance, I’ve done it in the past and most have been very helpful. Get it in writing, email, then there’s no arguements from management.