Portable generator earthing

[dobbslc]

I do a lot of generator work on sites and the big ones all need an earth electrode.
Anything portable under 10 kva doesn't.
If it's small and feeding portable tools you don't need an electrode either ( it wouldn't be portable otherwise!)

 

[the snooper]

Aparently not.
If you were using the genny to power a building or portacabin via a transfer switch then yes, but for powering stand alone tools and appliances no.
I googled portable generator earthing as suggested and it was all clearly explained over a couple of pages.

One question though to robotstar or snooper, if you did decide to use an external earth what problems could it potentially cause?

if you simply earthed the frame and did nothing else I doubt very much there would be any effect at all

 

[Gramas]

you will have to try it, it may well be ok on the lower settings, when you first arc up it draws a lot more power and once energised drops down

Yeah can only try, once I've moved house and got garage on the house will have sparky hook up welders own feed in

 

[the snooper]

I have a 5kva and the welder doesn't like it

 

[Jim Davey]

Keep the welding to a minimum, the weak point in an overloaded portable genny is the automatic voltage regulator AVR. It's a little black box with 5 or 6 wires going in that controls how much exitation goes into the windings to give you the voltage required. If you overload the genny the AVR has to supply a lot more excitation voltage and waves the white flag (mystical blue smoke and no power from the genny lets you know this has happened)

 

[the snooper]

Keep the welding to a minimum, the weak point in an overloaded portable genny is the automatic voltage regulator AVR. It's a little black box with 5 or 6 wires going in that controls how much exitation goes into the windings to give you the voltage required. If you overload the genny the AVR has to supply a lot more excitation voltage and waves the white flag (mystical blue smoke and no power from the genny lets you know this has happened)

most electrical gear runs on smoke and once it escapes it doesn't work anymore

 

[Jim Davey]

Exactly, I love getting paid to patch up smoke leaks in old welders.

 

[Justme]

I use a 6kVa to weld on but only at low levels.

If I want to weld thicker I use a 15kVa.

You do get cold starts but once its going it will cope.

 

[Gramas]

I use a 6kVa to weld on but only at low levels.

If I want to weld thicker I use a 15kVa.

You do get cold starts but once its going it will cope.

It's 3mm max I'm welding on a 195amp set that needs 6.5 kva to run on max so my gen is 0.5 short of that so hopes my be ok

 

[Jim Davey]

It's nowhere near as cut and dried as that, but try it. I'd keep the welder set as low as you can get away with though.

 

[the snooper]

It's nowhere near as cut and dried as that, but try it. I'd keep the welder set as low as you can get away with though.

yeah start low and work up, less chance of damage to the generator

 

[Justme]

It's 3mm max I'm welding on a 195amp set that needs 6.5 kva to run on max so my gen is 0.5 short of that so hopes my be ok

Mine is a 210amp mig.

There is no way I can run it at over 110amps on the 6kVa unit.

Above that is full of cold welds & does not maintain a nice smooth weld process / sound.

Def cant run 195 amps on 6.5kVa.

Roughly thats 195 amps x 27 volts (guesstimate) or 5265 watts.

You will have a PF of around 0.7 so that 5265 watts becomes 7.5 kVa before you even consider the efficiency of the unit which could be a low as 50% for a transformer type.

At full chat you want 15 kVa.

 

[Gramas]

Mine is a 210amp mig.

There is no way I can run it at over 110amps on the 6kVa unit.

Above that is full of cold welds & does not maintain a nice smooth weld process / sound.

Def cant run 195 amps on 6.5kVa.

Roughly thats 195 amps x 27 volts (guesstimate) or 5265 watts.

You will have a PF of around 0.7 so that 5265 watts becomes 7.5 kVa before you even consider the efficiency of the unit which could be a low as 50% for a transformer type.

At full chat you want 15 kVa.

Can only try I suppose , thanks for the reply And info