3 ph Welder from rotary convertor?

according to the isomatic website ..sellers of three phase rotaries

Boosters=99 are designed to run induction motors most efficiently. Welders can also be operated but the converter size should be chosen to be larger than the welder input power by 50%. If no power rating is shown then multiply the welding current by 50 for A series converters or by 30 for D series converters. The result will be the converter power rating in Watts for 100 % duty factor, often misnamed duty cycle.

so a 180 watt welder needing 16 amps would need 24 amps ..or 8 hp rotary converter if i got my sums right .

all the best.mark

meant to say 180 amp welder not watt.

all the best.markj

Hi, In my opinion you could use a smaller converter, as long as it's got a large flywheel to operate as an energy store. Often wondered about this. An electronic converter is a massive nono just to state the obvious.

You can do a lot with a large flywheel energy store. Would it be easy to add a flywheel?

Rob.

Ive looked at the plate, and its not even close to the amount of 3ph current required... Welders are thirsty things! Oh well, single phase it is.

Dave

Tell me about it, On my big TiG set I can get more heat off the gimbal on the electric meter than the torch.......

John S.

You can run some three phase wound transformer tigs and migs off single phase

but you only get half the power .

Done it with mine, a cebora special uno 200 amp tig

Just a mater of moving a few wires around under the lid

all the best.mark

Although it's counterintuitive, the added mass of a flywheel does not improve (reduce the effective source impedance) the performance of a rotary converter. Some rotary inertia is needed, but only enough to smooth the cycle to cycle torque variation. The inertia of the motor rotor is normally ample.

Static phase converters rely on start and run capacitors and the motor inductance for the phase shift mechanism. These will not work on a transformer/rectifier load.

Electronic VFDs will drive a three phase transformer rectifier load if DC output is the only requirement. However they will fail miserably if there are control circuits that need a sinusoidal supply waveform.

Jim