Re: Can I convert single phase motor to three phase?
Quote:
Originally Posted by
Jim Estes
I have a compressor motor that is blowing the starting capacitor. I have checked the voltage and it is fine. I was wondering if I could just convert this motor to three phase and eliminate the starting and run capacitor.
I have searched and found tons of articles about converting three phase motors to single phase. I am sure it goes both ways, but I was wondering if someone else had already done this. I have three phase in my shop and converting this motor to three phase would be cheaper than buying a new three phase motor.
I have no idea why it is blowing caps, but I suspect that it is from too many starts per hour.
Any help is greatly appreciated.
Jim
Jim, as for blowing caps;
Check voltage while actually starting, see if it dips more than 5, maybe 10%.
Check your unloader. When the compressor gets to pressure and cycles off you should hear a brief hiss as it releases the air from the cylinder, if no hiss, your unloader is not working and the motor is trying to start against a cylinder of high pressure air. If you hear a continuous hiss, your check valve is bad.
As for rewinding a single phase motor to 3 phase, I have done it several times and can coach you, but unless you work in a rewind shop it would be much cheaper to buy a 3 ph motor.
Re: Can I convert single phase motor to three phase?
On the subject of a quick fix in times when you are without a place to buy or get the necessary correct parts, I had a small home made air compressor bought from a deceased estate made from a small stripped down 4 stroke lawn mower engine and a 1/3 HP single phase motor.
In my infinite wisdom, which is normal for any DIY graduate with a degree in nothingness, I decided to guild the lily and connect it to a large 50 litre air tank as it was originally made with a couple of square tubes in the frame that served as a rudimentary reservoir.
Catastrophic results would be a new way of stating things went pear shaped.......OK, it started and did pump up to 80 PSI but it couldn't restart when the pressure dropped down to 50 psi.......motor go hot wouldn't turn quickly and the start windings shed magic smoke.....it couldn't get up to speed for the centrifugal switch to cut out the start windings.
It was soon realized that the motor was unable to lift the load once the load was fully loaded.........no load and it went for it big time.
As I am the tightest miser you can imagine when it comes to buying parts that I can't source from the scrap box, I just added a tee piece to the outlet pipe to the tank and a small gate valve.
On starting against a pressurised tank I just opened the gate valve and then closed it once the motor started, it's not on an automatic cycle for restarting as that was too sophisticated for the initial build plan, but it does have a pressure relief valve once it gets to 80 psi...........simple and it worked.
Some years ago I parted it from the big tank and just ran it direct on line as a wheeled portable for pumping tyres and blowing things off as I now have a 2 cylinder bigger compressor for all my needs, and I'm getting lazier by the day once something works and doesn't need improving.
I don't mess with single phase motors anymore now that you can buy a 3 HP VFD for under a $100 and get an automatic 3 phase supply speed controllable for cheap to get 3 phase motors
Ian.
Re: Can I convert single phase motor to three phase?
Quote:
Originally Posted by
ElectricSteve
Jim, as for blowing caps;
Check voltage while actually starting, see if it dips more than 5, maybe 10%.
The OP posted 15 years ago.
Hopefully he has cured the problem since!!!
Al.
Re: Can I convert single phase motor to three phase?
LOL.....I forgot to look at the posting date........probably all over bar the shouting by now.
Ian.