5-7hp 3phase motor needed

I would think this company could help you out.

've bought several used machine parts from them.

Thanks, They look pretty close. I'll give them a call come Monday afternoon. Have you delt with them before? Russ

Get in touch with a local scrapper., Or scrap yard. My local scrapper(s) regularily throw (sell) a lot of them for scrap value.

I asked one day if he had any, and the next day he stopped by with several

15 hsp motors, which I traded for a few barrels of chips. Can't get a better deal than that.

Pete

While you're rounding up a bigger motor for your RPC you need to be thinking about getting some more run capacitance. For reasonable voltage balance you will need around 212 microfarad of run capacitance. If you are not starting with a rope or pony motor (Rozen System) you'll probalby need additional start capacitance as well.

Over,

I bought the 5 - 7 1/2 hp static converter, he told me I could convert it over to a rotary, but all I had laying around was a 3hp and a 15hp 3 phase motor not on my mill. All though I've been thinking how cool it would be to have that 15hp spindle on my bridgeport. I've heard too big of a motor will blow the caps so I didn't want to try that, at least not until they are in a box...

Check out what I have under this site, click on phase converter about 3/4 of the way down..

Thanks for you help, I do appriciate it.

What are the values of your capacitors, both run and start?

Well I don't know which is which but there are 2 smaller ones that have

540-648 uF 125 VAC that look like they are wired in series and 2 larger ones that say 70UF 240VAC on them looks like wired in parallel. Does that help?

Russ

Unless you can tell run caps from start caps, any suggestions for a larger idler motor would be of no help to you.

Thanks anyways, as long as it hits it's specified hp I'll be happy. Another guy who has a 40hp phase converter hooked up in his pole barn remarked these looked awefully big for a 5 hp converter but he said it's better than blowin them. Russ

Russ

The 3 HP idler will undoubtedly provide all the "third phase" you'll need for running a 5 Hp 3 phase motor on your machine. Big idlers and tuned idlers help spin up tool motors but once the machine is spinning, they do little for improving the power delivered to the load. If you need to run the 5 HP machine at full power for extended time periods, you may notice some heating of the tool's motor. The idler might get hotter that you like too. But, the 5 HP machine motor will deliver its full rated 5 HP when fed thru a 3 HP idler. Add-on fans will bring the temperature down to your satisfaction (if needed). That said, if this was my project, I'd make the spare 15 HP 3 phase motor into an idler instead of using the 3 HP motor. That would make all your 5 HP 3 phase motors run as though they were being fed from the local power company's 3 phase.

Jerry

Jerry, Thanks for your input, and info. I don't know if I really have the juice to run that in my garage though. I've really only got 50 amps going out there and was leary of putting a 10hp converter out there let alone a 15. Do you think that It would get started on that low of amperage?

Russ

Russ

I agree with you. The 3 HP idler seems like a good choice for your shop.

Jerry

I'd try it. If it pops the breaker... Then un hook it. I've had a 30hp idler on a 100 amp circuit. running a couple of full sized VMC's for years.

I've got a 15hp converter on a 30 amp circuit for many years. No (known) problems.

Pete

Pete

How do you spin up the 15 HP idler?

Jerry

I'd be more concerned about blowin the caps. My buddy did that and he said it made a huge mess with all that hot oil flying all over. He's got a couple full size VMC's (Haas) and 1 cnc turning center aaannndd 2 manual lathes. I've only got one little CNC Mechtronics that I hope will work. I believe it's got a 5 hp spindle motor on it. Russ

Russ

You dont need "caps" in the circuit *after* the idler is spun up to synchronous RPM. I assume you refer to someone who tried to start up a too big idler with inadequet capacitance. The blown caps werent on that 40 HP phase converter, were they? A little additional capacitance in the idler's start circuit will normally spin up the idler so quickly that "blowing" them isnt expected to be a problem. The start capacitors for a 5 HP idler are relatively inexpensive

Jerry

If you are running a CNC off this rig then you should have some run caps to even out the phases. If your phases are not within 2-4% of each other you will have problems. I use a 40hp with a large buck boost transformer and a bank of 50mf run caps and get 212-214-211v as an output under load (spindle cutting al. 15% load, with two axis driving). Remember, the balance you get under no load will be different. I use a pony to spin mine up prior to starting, mainly to avoid a large current demand on start-up.

1200 mfd of dry starting caps. Snaps right up to speed.

Pete

Dave

I have no disagreement with anyone who wants to balance the voltages from an idler. I do know that there are many CNC machines that are being run successfully from idlers without balance capacitors. What is the negative result associated with your CNC machine when run from unbalanced idlers? I may be overlooking something.

Jerry