vfd or phase converter?

[jakeh]

I am in the process of getting a new shop set up. I have a one horse rpc that has done well for my small lathe and grinder, but will need to go bigger for my 5 hp air compressor and a miller intellaweld 650. How large a phase converter would I need for the welder? Would it be possible to balance the voltage on the three phases for motors ranging from 3/4 horse to whatever the welder will draw? Would a vfd be a better choice? I don't know how or even if a vfd would work to power the welder.

 

[rsanter]

A VFD will not work on a welder.
Look at the welders specs, some welders are single and three phase. In that case the welder only uses two of the three phases

Bob

 

[jakeh]

I don't understand. If the welder uses only two phases can I run it on 220 single phase?

 

[454ragtop]

Can't help on the welder, but I'd recommend changing the motor on the compressor to a single PH one.
Jim

 

[A_Pmech]

Yes, that machine can be made to run on single-phase. How big of a service do you have? That Intelliweld is going to need about 200 amps of it.

I'm all for large equipment, but a 650-amp CC arc welder in a home shop is probably a bit excessive.

 

[930dreamer]

Build a 10hp phase converter for the compressor and smaller tools, I can't help on the welder.

 

[Packard V8]

Careful on using a rotary phase converter on an air compressor. Some compressors will start under load and run on a RPC and some won't. The rule of thumb I was given is it takes a 50% larger converter for an air compressor than the horsepower of the motor on the compressor.

My machinist has a shop full of RPCs, but he has to run his compressor on a large single phase motor.

jack vines

 

[larry_g]

http://phase-a-matic.com/VoltageStabilizerDescription.htm

Give the company above a call. They are the professionals. What you are getting into is pushing the limits of most garage hobbyists capabilities. I had a friend that powered his shop, including some CNC stuff and swore that the power from the Phase-A-Matic was better than some commercial power.

lg
no neat sig line

 

[sailah]

I had a 10hp RPC in my wood shop for running up to 7.5hp motors. My compressor ran fine and was 5 hp. I would double the size for hard starting loads. My table saw was the biggest load because it was a direct drive and swung a 18" blade. Lots of inertia to get that running.

I also bought a miller gold star 400 TIG welder with the plans of running it on three phase as it was three phase only. It would not work. I had my buddy who is a nuclear electrical engineer and runs serious electrical **** at the power plant come over and diagnose. He hooked up all sorts of test equipment and basically said...

"The SCRs are not firing, the power isn't accurate enough". Or something like that. Basically the rpc was good for motors, but not electronics. I sold it and bought a single phase machine. A VFD will def not run the welder.

 

[jakeh]

I realize that a 650 amp welder is more than I need, and most likely never will push it that hard. Its my nephews machine that he got for $350, its like new and he wants to bring it over to let me use. It would give me stick and tig capabilities that I don't have now and would be a power supply for the induction forge that I've been jonesing for. I have 200 amp service in the shop.