Need 600V AC

[Grayham]

I got a very good deal on a 30hp electrically driven air compressor. Problem is, my garage only has single phase 220v ac power and the motor requires 600v three phase and draws 30A. I am quite handy at building and fabricating and have a slightly better than average knowledge of electricity. I want to build a power supply for this compressor but am not sure which is the best way to go about it? I have 220v 200A available in the garage. Should I build a couple of step-up transformers and a phase converter or a large alternator or? What do you suggest? Any input would be very helpful. Thanks.

 

[Geniere]

Bad deal! The only practical way to get 600 volts, 3 phase ac would be a motor generator set. That would cost BIG, BIG bucks. 30 HP is about 22500 watts. Starting surge would propably trip your 200 amp breaker no matter how you did the conversion.

Two suggestions: Get a 30 hp gasoline engine or a 240 volt ac, 4HP motor to drive the compressor. With a low power motor, the compressor will probably work, but deliver a much reduced volume of air. Max pressure should stay the same.

BTW - Residential voltage is usually 230-240 vac phase to phase and 115-120 vac phase to neutral

 

[NickE]

220V single phase is going to give you around 415V 3-phase (standard industrial supply in most parts of the world) - with transformers and phase converters you'd be able to get to 600V P-P, but you'll lose quite a bit in the conversion, so the 200A is going to be right on the edge. You'd need some sort of starter to get round this - star-delta probably wouldn't be enough, so you need a soft starter which is getting into big money, even for a small motor like this one.

All in all, changing the drive motor to suit your supply is probably going to be the most economical solution but as already mentioned above, power is limited on single phase drives.

 

[PowerEngineer]

I have to agree with Geniere...bad deal!

There's no way to run a three-phase motor starting from a single-phase supply, which is all you have in a normal household supply. If you had a second phase, then you could possibly configure them into an open-delta which could serve a three-phase motor.

Sorry.

 

[dkozloski]

If the compressor is U.S. made you will be able to convert it to run from an internal combustion engine very easily. It probably already has an unloader which wiil work as an automatic pressure control device and you should be able to get a VW or some other air-cooled motor for a prime mover to eliminate having to fiddle with a coolant system. It would be best if the prime mover was some sort of industrial type that included a governor. You can get full pressure out of it with a smaller motor by adjusting drive pulley sizes but at a reduced pumping rate. I have seen dozens of conversions of this type.

 

[xenos500]

Yes, internal combustion is greeat. I would replace the motor with a small diesel..... but thats just me. Electric motors are kinda cool too, Maybe the best way it to run the electric motor off a generator..(diesel ) Thats how trains work...they work pretty good.

see ya and good luck

 

[Mday]

call your local power utility company, hire an electrician.

otherwise, you void any insurance you have, and will have a fire.

 

[rectifire]

As a licensed professional electrician, I can tell you that there is NO WAY you can get the kind of power you need to run this thing from a 220V 200A single phase residential service. It is simply not possible, so don't even try.

For example, the minimum size breaker needed to legally power this motor from a 220V single phase service, is over 250 Amps. This exceeds the total rating of your whole panel! There is no way you could even buy such a breaker for your panel!

This is not even taking into account the extra power used by phase convertors and transformers.



Like others said, a gas or diesel engine would be your best bet.
Good luck to you!

 

[Mark R]

You could try the simple solution - ring the electricity company and ask them to install 600V in your garage. If you give them the impression that you are going to be running heavy equipment, they might even do it for free.

Failing that replace the motor with a smaller one, and make appropriate changes to the belt drive system to reduce the flow rate.

 

[Okimoto]

you can run a phase converter maybe? Or maybe you can take the motor into an alternator shop and have them re-wind the armatures for a lower voltage and single phase power, if thats possible?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2560050356

if you run the phase converter they have on ebay, and hook it to this motor: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2560872468&category=42922
then you can run your air compressor with little to no loss of performance.

the total would be pretty cheap all things considered, and might actually run within your specs?

 

[compudog]

An expensive, though viable solution would be to replace the 600 V motor with a 3 phase 240/480 volt motor and then purchase an inverter (VFD, ASD) to run the motor from your single phase supply. The inverter would need to accept a single phase supply or be programmable to accept a phase loss. Usually the inverter's output has to be de-rated when supplying only a single phase input.

The more I think about this, the better an internal combustion engine sounds. It may be cheaper to sell the compressor to someone that has the 600v 3-phase and pick up a small residential model.