Running plasma off a generator

[akpilot]

I live off grid and use a 25 kw generator for the Plasma, Mill, Lathe, ETC. the plasma I have now is a TD Cutmaster 82 which doesn?t seem to like the generator, very unstable over 40amps, even though the generator is capable of much higher output. Does anyone have experience running a plasma off a generator? Is this a common problem? Will a Hypertherm work any better? (Jim any input?)

[beefy]

Is the generators freqency (rpm) accurate.

Also how well does it maintain it's rpm when a load is applied. Does it bog down then build up again.

The same goes for the output voltage.

Keith.

[jimcolt]

Not all plasma systems work the same on a generator output. Plasma systems tend to have a relatively high inrush current.....which often can cause a voltage droop as soon as the arc tries to fire, which will cause the plasma to not fire. Some plasma systems will produce a lower output cutting power (watts, which is amperage x load voltage) if the input voltage is unstable.

The following Hypertherm units were designed with generators in mind: Powermax1000, 1250, 1650, Powermax30, 45, 65, 85 and 105. These systems have a "boost conditioner " circuit that senses the input voltage real time and adjusts the output power to compensate. The initial startup has also been designed (this took torch and power supply development) to minimize the starting inrush current. On the Hypertherm web page there is a "generator chart" for each system....this tells you what size plasma will work on what size generator. There are many cases where you can use a relatively small generator that will allow the plasma to cut at reduced power. Where the charts suggests "arc stretch"....this means that you can push the plasma beyond its advertised cutting capability with a properly sized generator.

I have attached a suggested generator chart for a Powermax65. This chart shows that you can use a Powermax65 at its rated capacity on a 15kW generator (full arc stretch at 65 amps),and at reduced outputs with smaller generators.

Jim Colt

Powermax65generatorchart.jpg

[beefy]

Jim, that's the type of response that made me glad I bought a Hypertherm

Keith.

[akpilot]

That's the type of response that make me wish I had bought a Hypertherm!!! Thanks JIM. I was on the verg of buying a machine tourch for my TD, but now I might just sell it and buy a Hypertherm.

[pony]

Does your generator have a load only when the plasma cutter is in use, or do you use it to power other devices that draw a constant load? I'm not sure if you are running primarily solar and the generator for your cutter/mill/lathe, or everything off the generator (lights, table controller, etc)

If your generator has "idle control", and is otherwise unused until the plasma fires you might try running it with idle control off.