industrial welder. any advice

[Davey1988]

Hey guys

I want help on this forum about cpc and I heard I won't get any am I right?

 

[davesparks]

Calculate cpc size using the adiabatic equation, exactly the same as any other circuit.

And put your best tin hat on before anyone else answers this, if you aren't on a wind up you are going to be catching some serious flak!

 

[Davey1988]

Cheers for your help.

 

[D Skelton]

Oh dear God!

Step away from the welder!

Get a qualified lad do do the job, watch and learn.

 

[davesparks]

Aaaaaaand they're off!

 

[davesparks]

Cheers for your help.

So, what answer have you got after using the adiabatic?

 

[Davey1988]

No ze provided and unable to measure. Not sure on the cable sizes yet especially cpc So ain't worked out r1 and r2.

Lovely.

 

[davesparks]

Where's the first post gone?

 

[Davey1988]

To save future embarrasment I deleted it.

2 phases. No neutral. And cpc
80 amp fuses per phase. Max leakage imo can be no higher than 160amp.

First time in dealing with welders not 100%

 

[davesparks]

You've got serious problems if you've got a leakage current of 160A

 

[Davey1988]

Maybee

 

[davesparks]

No, they use the cpc as a cpc and a neutral as a neutral if one is required. It sounds like the machine you have is designed to operate on two phases of a three phase supply, unless of course it's designed for a two phase supply?

You need a lot more than a little guidance, you clearly don't understand the first thing about the job you are attempting to do.

 

[PEG]

thinking worst case senario. Do welders use a cpc to act as a neutral. little guidance is all I need and I'm finding it really hard to get it on here.

Some welders have 200amp - 400amp earth clips.....

I think you are getting confused with the terminology,referring to the OUTPUT side of the machine.

The terms and figures only make sense,if this is the case.

Do a bit of research,and all will become apparent...but do not attempt,if unsure,and some other human is to test its' operation...:conehead:

 

[Knobhead]

Think along the lines of electrode (live) and work piece (neutral return). The I/P and O/P are two separate entities.

Where I’ve seen things go badly wrong is when the CPC has been used for the return. Do some reading on the subject, as a hint, don’t bother looking in BS7671.

 

[plugsandsparks]

Think along the lines of electrode (live) and work piece (neutral return). The I/P and O/P are two separate entities.

Where I’ve seen things go badly wrong is when the CPC has been used for the return. Do some reading on the subject, as a hint, don’t bother looking in BS7671.

Yep, I recently had a call out because a welder had set the cpc on fire in the DB and it even made the trunking rattle, lol. I repaired the circuit and offered to check the welder to make sure it was wired correctly but they thought it was dangerous so the had ditched it before I got there...

 

[Knobhead]

Yep, I recently had a call out because a welder had set the cpc on fire in the DB and it even made the trunking rattle, lol. I repaired the circuit and offered to check the welder to make sure it was wired correctly but they thought it was dangerous so the had ditched it before I got there...

Welding sets have been the bain of my life, more correctly idle welders who can’t be bothered with the return.

Cables on fire, bearings seized, you name it, they can bugger it up!

 

[davesparks]

Being back acetylene welding, that won't bugger your earth wires up!

 

[plugsandsparks]

Being back acetylene welding, that won't bugger your earth wires up!

May sound a little sad, but when I was a lad, I did spend some time in the welding shop ONLY because I was fascinated by the cutting torch and how good the welders were at cutting thick plate. Anyway when I eventually got them to let me do some cutting I was ecstatic, can still remember the day....

 

[davesparks]

May sound a little sad, but when I was a lad, I did spend some time in the welding shop ONLY because I was fascinated by the cutting torch and how good the welders were at cutting thick plate. Anyway when I eventually got them to let me do some cutting I was ecstatic, can still remember the day....

Ive got some of my grandad's oxy torches in the shed, he was a diesel fitter working on mining machinery and trucks etc in australia. theres a normal size cutting torch, straight torch about 2' long and a circle cutting guide to hold the big torch and cut perfect circles.
Some of the other gems he's passed on include a 3 legged puller which could have a role in war of the worlds and an 1" drive socket set.

Anything I have no use for or don't want gets donated to charity

 

[Davey1988]

Any advice on where best to research welders. As yous say noT bs7671

Cheers fellas. I'm having a debate at work and I advise they oversized the phase cables (ain't disputed the cpc as that's what I'm working out lol)

 

[davesparks]

Any advice on where best to research welders. As yous say noT bs7671

Cheers fellas. I'm having a debate at work and I advise they oversized the phase cables (ain't disputed the cpc as that's what I'm working out lol)

Why oversize the phase cables? the correct size cable will do the job fine

 

[Davey1988]

That's why I'm trying to research a little first before I look like the noob. Which I am but.... its 80 amps per phase and they want to install a 70mm cable capable of carry 196 amps per phase. (Only thing I can assume is to gain a 35mm earth cable Which may be required. That's why I'm wanting a little advice

 

[davesparks]

That's why I'm trying to research a little first before I look like the noob. Which I am but.... its 80 amps per phase and they want to install a 70mm cable capable of carry 196 amps per phase. (Only thing I can assume is to gain a 35mm earth cable Which may be required. That's why I'm wanting a little advice

CCC isn't the only consideration when selecting a cable.
Are you actually a qualified electrician?

 

[Davey1988]

Never said it was. I've worked out 36mm earth cable required. But don't understand the phases. Probs convience.

 

[davesparks]

Are you responsible for designing this circuit?

 

[davesparks]

Never said it was. I've worked out 36mm earth cable required. But don't understand the phases. Probs convience.

Assuming that is copper you have worked that out for then you'll obviously have to use 50 mm

 

[Davey1988]

Someone else designed it. I'm trying to understand it.

They specified 70mm. 35mm copper.

I have to install it and I think it's way to big.

 

[Davey1988]

K value 46
zs .31
voltage 415
Diss connection time required 5 seconds.

 

[davesparks]

Someone else designed it. I'm trying to understand it.

They specified 70mm. 35mm copper.

I have to install it and I think it's way to big.

If a designer has specified it then that is what you install, it's their name on the paperwork and their neck on the block if it's wrong.

 

[davesparks]

K value 46
zs .31
voltage 415
Diss connection time required 5 seconds.

Length of circuit, max permitted Zs, inrush current, power factor, max permitted VD, ambient temp, installation method, type of cable, conductor operating temperature?

 

[Darkwood]

Welding sets have been the bain of my life, more correctly idle welders who can’t be bothered with the return.

Cables on fire, bearings seized, you name it, they can bugger it up!

You and me too..been there posted some pics in the past ..seen welders take out 10mm bond in trunking melting into every other cable blowing main cutout... cost 6k to rewire and regardless of our warnings same guy did the same thing 2 weeks later - sacked instantly then and we had to re-do our work again albiet not as bad - 10mm earth and 600amps don't mix....

 

[Knobhead]

Sorry to say I’m out of here, the OP clearly doesn’t know what he’s doing. That said it doesn’t sound like the designer does either.

Heavy welding plant is dangerous and not for a trainee to be playing about with.

 

[Davey1988]

Length of circuit (25 meters),
max permitted Zs 0.31,
inrush current, max 80amps it runs off 50% power wave
power factor (unknown but the fuses are 80amp built in the machine 80amp max. N/A)
max permitted VD, 25m probs 2vd max. (No worries here)
ambient temp 30o
installation method E,
type of cable SWA 4 core.. I said the earth was copy my bad it's sheath, (was tired)
conductor operating temperature? 40 - 60o (90o cable)

Ohh and disconnect te required 5 seconds.


Tony your right I don't know about these but I'm the type of guy who likes to find out why it's this cable.

 

[Darkwood]

Take a pic of the plate Davey or supply the make and model of the welder, welders are not for the inexperienced as Tony quite rightly points out and require a lot of respect, some simple info you forget to mention or don't realise is important can be the difference between an incorrect install with issues to even a dangerous setup.

Welders can be designed for multi-tapped inputs and the plates can become confusing very quick, as a Trainee your enthusiam is great but you should be working under someones wing here and this is the person to answer your queries as (s)he's will have all the facts to hand as they have designed said circuit...

Your trying to win the marathon here just after you learned to walk, trying to understand this side of the job can make what your learning very confusing indeed as you'll see obvious conflictions to what your been taught so I would get yourself a good few yrs behind you before tackling such equipment.

I've seen seasoned Electricians mess up on machine/plant supplies just because they are clearly out of there depth, its not about just designing the supply, its also about knowing the peak and duration of power demands and how the loads work..... often is the case where you haven't got any info to reference as with most older plant.

 

[netblindpaul]

Any electric welding set made to current standards must not be able to "take out" any supply side earths etc.
If the set is not totally electrically separated between primary and secondary, then it does not meet the current build standards for it to be legal for sale, and if it is already in use then it is considered lethal by HSE & TWI I don't believe that the IET would argue either, and must be put out of service immediately as it is no longer considered compliant with PUWER98 nor EAWR89.

 

[mechelec]

Used to do some maintenance work for a small machine shop a few years ago. Had to replace bearings on one of his lathes on several occasions because he used to centre 2 pieces up on it and weld together. Problem was he would put the welders earth clamp on the body of the lathe and weld the piece in the chuck.

 

[Darkwood]

Used to do some maintenance work for a small machine shop a few years ago. Had to replace bearings on one of his lathes on several occasions because he used to centre 2 pieces up on it and weld together. Problem was he would put the welders earth clamp on the body of the lathe and weld the piece in the chuck.

Considering they make rotating earth clamps specially for this purpose then this bloke is an idiot, what he did there was dangerous both to personel and the integrity of the bearings.... they could have easily failed catastrophically after the damage sustained from the high currents bridging the bearings considering lathes can have heavy loads spinning with high inertia he is lucky he got nothing worse than bearing replacements... if thats true I'm truely facepalmed!!!!

 

[Geordie Spark]

Used to do some maintenance work for a small machine shop a few years ago. Had to replace bearings on one of his lathes on several occasions because he used to centre 2 pieces up on it and weld together. Problem was he would put the welders earth clamp on the body of the lathe and weld the piece in the chuck.

Things like that grind my gears!!

A Lathe is a precision machine tool and should be treated as such.

It is NOT a freaking welding jig!!!! :32:

 

[PEG]

Things like that grind my gears!!

A Lathe is a precision machine tool and should be treated as such.

It is NOT a freaking welding jig!!!! :32:

...Unless it's in a propshaft repair shop,in which case,that's mainly what it is!...albeit with running earth arrangements in place.

Any welding operation,carried out on machinery where current continuity bridges lubed slide beds and bearings,is going to be costly...:icon12:

 

[Knobhead]

https://www.youtube.com/watch?v=5JbnDXw-0pM

https://www.youtube.com/watch?v=-aEuAK8bsQg