3 phase shop air compressor Electrical Question

three phase compressor on single phase power with a converter? to much of a load. tools that freewheel are not a problem, but a air compressor is under a big load alot of the time. a drill press, disc sander, even a 7hp table saw is ok, because the load can come and go. once a air compress is charged up, every time it starts its under load. rotary converter is better than a static. in fact, a big rotary converter can power up a shop full of three phase machines is its well planed out.

 

Around here for a power co to put 3 phase in would require you to be zoned commercial. I would assume that type of standard would be normal for most towns.

 

Go-twichy is right, no load is ok with a phase convertor. Since start up takes more amps, that is why an unloaded lathe, drill press, mill, can start but a compressor already with air pressure in the tank has trouble.

 

Got a blueprint off ebay & made a rotary phase converter.Jimmie King

 

Smart thing to do first is look and see what is running down the alley past the shop, might be single phase, might be 3 phase. Where I am at if it happens to be going by, they will drop it on a separate meter, not a problem. A good rotary would run it if sized correctly. I am not an electrician, but I fail to see where a properly sized VFD would not run it as well. If you want to delve in to the possibilities the Practical Machinist forum has a sub forum with lots of reading, and lots of expertise that posts there.

 

We put in a 3 phase pump on the farm It required a new power pole, with 3 new transformers, $ 4 k to the power company and $ 1 k in a new panel and hookup to the electrician. , and we have a yearly fee of $ 1200 minimum power bill as a standby cost , we pay if any power is used or not , but 80 % deducted from the first power bills $ 1300 amonth when we are pumping.

 

So you are saving $1300 a month? In four months it's paid for itself. Pretty good.

 

Phase inverters will work, Or see if you can get a good deal on a single phase item...trade, maybe ?

4TTRUK

 

I'm the owner of an electrical contracting company....I don't care for phase converters, I make better money on a new 3 phase service ...However I have seen rotary converters function ok for high starting load motors...I have no experience with solid state devices.Static converters are not a good choice for a compressor load. Just make sure your existing electrical service is in good shape and the convertor is of adequate size. Don't cheap out!!

 

It's illegal in all states to run three-phase to a residential service. Sell the three-phase motor and install a single-phase in its place. Easiest, cheapest, and safest solution to your problem.

 

Illegal ? would that be utility company rules or an actual law?

 

It's not illegal. It's expensive and requires some paperwork, but not illegal. It was $4500 to get 3PH dropped in here back in 03. No thanks, bought a 10HP 1PH motor for $650...new from Grainger. Runs almost exactly the same as it did on 3PH, but it takes 5 seconds longer to cycle on single phase power. It used to pump 205gal from 125psi to 150psi in 1min 15sec on 3ph, now it's 1, 20.

 

we did a house out here and it cost the guy 15,000 buck! they had to run another pole down a street to get him that third leg. but he was loaded and didnt care what it was going to cost him. the only thing in his house that was 3 phase was his air compressor. they didnt make ac units small enough for a home in 3 phase. that still cracks us up about it.

 

To be honest I have never seen three phase in a house in a lifetime of electrical work.However,I don't do residential work,so...I'm sure it exists. I deal with the utility company a lot and never heard of of three phase in a house being illegal from them but generally speaking they won't want to provide it unless you have a legitimate need.Like a business in your house and that may be the "illegal" part,running a business in a residential neighborhood.
Cost of three phase? Last small three phase service I did was to a new pizza joint.200 amp 42 space panel,180 foot of 4 inch underground PVC conduit and wire,inspection fees.Owner paid for the excavation and backfill.Charged $ 4200 for the service ,no branch wiring.The owner paid the utility company 1200 bucks for their work.Three phase was on the pole at the street.
Another recent job was a 200 amp three phase service to a small butcher shop.Conditions allowed me to use an overhead service with a 4 wire SE cable.So this would appear similar to a typical residential service. My bill was $2800 for just the service.Utility company charged the owner about $800 for their hook and transformers on the pole with existing three phase.
This is in Western NY state and utility company hook up prices and policies on electrical services are all different