Beware Using Generators

[Mee]

Only today did we have an issue, so thought I would post for members information.

If you use a generator and a welding or similar plant then make sure your generator has AVR or auto voltage regulation if you use an invertor welder as they are sensitive to incoming voltage as we have blown an invertor welder today.

As a company we use a national contractor to supply our generators for sites with no power, or insufficient power for our needs and the contract with them stipulates that only AVR generators are to be supplied, today one slipped through the net and we were supplied with one generator without AVR and welder went bang.

Fortunately two generators were delivered, and this project only started on Monday and the prep work is in its infancy so only one welder was working, and they had a spare.

 

[Jim Davey]

AVR is not the only factor at play, if the generator is under specced then no AVR in the world will make up the difference. Similarly, if the generator is big enough, it doesn't matter if it doesn't have AVR control as the voltage will not be adversely effected by the load of the inverter resulting in trouble free running. Most national fleet operators and manufacturers recommend if you want to run an inverter of a generator find the max mains potential KVA draw, then double it for specifying a generator.

For example 4 KVA mains required flat out, get an 8 KVA generator.

It's not guaranteed that an inverter will be damaged for certain running it on an undersized generator, enough "get away with it" but plenty don't and I've had enough experience of voltage drop killing inverters over the years to heed the mfrs recommendations now.

 

[WorkshopChris]

Its surprising how many times you see a capable generator supplying a welder through half a mile of 1.5mm cable then people blame the welder or the generator for poor performance or problems.

 

[Jim Davey]

True, the system is only as good as the weakest link.

 

[HMB]

Aggreko. The way forward

 

[Jim Davey]

Hammer-walnut.

 

[gt6s]

AVR is not the only factor at play, if the generator is under specced then no AVR in the world will make up the difference. Similarly, if the generator is big enough, it doesn't matter if it doesn't have AVR control as the voltage will not be adversely effected by the load of the inverter resulting in trouble free running. Most national fleet operators and manufacturers recommend if you want to run an inverter of a generator find the max mains potential KVA draw, then double it for specifying a generator.

For example 4 KVA mains required flat out, get an 8 KVA generator.

It's not guaranteed that an inverter will be damaged for certain running it on an undersized generator, enough "get away with it" but plenty don't and I've had enough experience of voltage drop killing inverters over the years to heed the mfrs recommendations now.

In total agreement with of all that. Having experience with welder and generators hire up to 550 Kva. I have a generator and I would never dream of using an inverter off it tho I have run the MIG. But not ideal so now I run the MIG the TIG and the plasma cutter only off the mains.

 

[HMB]

Hammer-walnut.

Can't beat a bit of aggreko

 

[Jim Davey]

That is not a little bit. It's a load of aggrecko.

 

[HMB]

Lovely v16 diesels iirc. Needed ear defs to venture inside

 

[Mee]

Certainly not underspecced Jim, 220 KVA as it will be running some large loads.

 

[Jim Davey]

Certainly not underspecced Jim, 220 KVA as it will be running some large loads.

Was the inverter running off the 220 KVA when it failed? If so what voltage was it putting out? Anyone test for harmonics? What leads/distribution etc? Too many factors to point straight at AVR control. I agree I rather have AVR control for sure. What inverter was it by the way? Some seem very susceptible to this type of failure.
The GYS E200CEL MMA set has FV flex voltage, meaning it can automatically adjust itself on the fly to accept an input voltage from 85-265 volts, that's pretty impressive and makes me a lot mor confident to put them out for use on generators. (The current still needs to be there for the work to be done though, it doesn't mean you can run a 4mm rod off a 2 Kva genny now lol, it just means the set has better protection against variable input voltage, often a problem with temporary or inadequate available site power.)

 

[Mee]

As far as I am aware it was load sensing and non AVR, it runs at standard 3 phase as well as 240 and 110V.

The generator company agreed it was non AVR and shouldn't have been sent out for us as they can exceed 300 volts, their words and not mine. It was one of the older Millers which was damaged and they have just said replace it and send us the bill and we will amend your hire invoice accordingly, so admitting liability.

As work was starting and we are in the set up phase of the project the only 240V was to run the welding equipment doing the prep work, the heavy guns are going in to the site in a few weeks.

 

[Jim Davey]

Fair play, good of them to admit it, voltages that high are not good for more than just inverters.

 

[Mee]

Admittedly, but transformer welders handle them better.