Welder problem

mac_iomhair

Welder rated for 72 Amps to install in a garage.
With a 63 Amp main switch fuse and an 80 Amp ESB fuse in the meter cabinet.

i know this welder is just way too big to be installed in a domestic premises but how would i get around it without it tripping out all the time.

would a 50 amp mcb do the job?

bertie1

No. Not if you horse up the output of the welder.

2011

i know this welder is just way too big to be installed in a domestic premises but how would i get around it without it tripping out all the time.

Perhaps not!

Am I correct in assuming that it is single phase???

Welder rated for 72 Amps to install in a garage.

When your welder gives out 72 amps on the secondary side (the side that you are welding with) it does this at a voltage that is far lower than on the input side of the welder (the side that you plug into the socket). The result of this is that the current drawn from your socket is far less than 72 amps. How much less? This will depend on the rating of your welder, look on the nameplate. You can calculate the approximate input current from the formula below (ignoring losses):

Input current = (Output Current x Output Voltage)/ Input Voltage

= (72 x Output voltage) / 230

So if the output voltage was 44 volts at 72 amps the welder would only draw a bit over 14 amps on full load. This welder would be rated at about 3.2KVA.

From this equation you should be able to size your MCB. If this is a single phase welder the chances are it is designed to take a 16A commando socket like this:



A 20A MCB would be OK. I would suggest that you wire the socket in 4 sq. cable at a minimum and put it onits own circuit with its own RCD (or better still its own RCBO).

Can you confirm what type of plug is on the welder and what rating it is??

Sometimes the rating is given in KVA (VA * 1000).

mac_iomhair

hey, there was no plug with the welder. i have it wired up to a 16A socket simalar to the one you have pictured. maybe i should upgrade that to 20A or 32A. The information I got on it was that it was 16A but when I wired it up in 2.5mm and on a 20A breaker it was working on mid output but tripping when turned up. i was thinking on putting in six square and a D rated 20A MCB. (currently its a B rated domestic mcb) but if you think its own RCBO would be better maybe I should go with that then?

http://www.parweldltd.com/pdf/xtm181m.pdf
theres a link to technical data sheet. mine is the XTM301C.
page 8 has all the technical spec it. see what you make of it...thanks:)

2011

D type MCBs are not designed to protect socket outlets! From a quick glance at your link it would seem that the smallest welder shown should be protected by a 32 amp fuse!! This means that a 2.5 is completely unsuitable! I did not have time to read it properly.

My advice is to get a qualified electrician to take a proper look at this. As well as shock risk there is increased fire risk now with large currents. DIY is great, but you have to know your limit.

mac_iomhair

its a radial circuit. fed from an rcd and an mcb (d rated for transforrmer/welder)
there is nothing wrong with that for feeding a socket?

2011

D type MCBs are not suitable for socket outlets.

You may well get it to work, but to be sure it is safe is a different matter.