Converting 3phase drill to single

[JimM]

I've given up expecting any sort of decent performance from my cheapy Clarke pillar drill so am looking to upgrade. There seems to be a few decent looking second hand drills around but most of them are 3 phase, how would I go abpout converting one of these to single phase. Is it just a case of swapping the motor and if so what sort of spec should I be looking for in the replacement ie Watts, RPM etc

Cheers

Jim

 

[shenion]

You can swap the motor, that is the simplest. Find a motor with the same shaft, rotation direction, RPM and horsepower.

There are also static phase converters. They will run the 3P motor off single phase. You will get only 2/3 the rated power out of the motor.

 

[Drains]

Jim, motor speeds are dictated by the number of poles, dont worry too much about the specific speed rating on the motor, but you are looking for something in the region of 3000rpm (2 pole) or 1500 rpm (4 pole).
You should try and match the frame size too (printed on the manufacturers plate), that way the shaft size, shaft height and hole centres will be the same.
And as Shenion says, check the direction of rotation. It's not a problem with three phase as you can reverse 2 phases and so reverse rotation, but on single phase it's normally pre set. From what I recall, direction is rated as looking towards the shaft, clockwise/counterclockwise. (or right hand/left hand)

 

[rtbcomp]

On some single phase motors you can reverse direction by swapping over a couple of wires in the connection box.

 

[irondarren]

jim look into a 3 phase power converter, i have a 4kw rotary one its great. expensive to buy but once you have it, you can buy any three phase tool and use it (within the scope of the converters output). alternative is fleabay and a second hand single phase motor, or machine mart sell new ones, you just have to get the right spindle and frame size

 

[snowcat]

jim look into a 3 phase power converter, i have a 4kw rotary one its great.

actualy fairly easy to make if you have an old 3ph motor, Did one a few years back just for the shear hell of it.

 

[JimM]

actualy fairly easy to make if you have an old 3ph motor, Did one a few years back just for the shear hell of it.

Can you give us a few pointers how I'd do this ??

Cheers

Jim

 

[snowcat]

No problems, I cant rember the exact wireing diagram but can pull the lid off the one i built and sketch it up for you,
For now il give you a run down of the princibles, You will need a 3ph motor, around 5hp is a good size this will alow you to drive about a 3.5hp motor, A 3ph contactor(and i think i put a 240v coil in it) , and a couple of capacitors, Il have to search for the fomular I used to calculate the size,.

Ok basicaly you produce 2ph plus a neutral, 3ph motors will run happy with this, the cap,s are used to "shunt" the converter to make it spin, then once turning it rotates powered by ph1 and neutral, because of the generator effect the 3rd winding produces the extra phase.

Extra caps can also go in across the phases to add a smoothing effect.

Sounds complex but a day of head scratching had it working just fine,(iv got 3ph, it was done to prove a point)..

Il sketch you up a diagram over the next couple of days, and it should become clear

 

[zoezant]

jim look into a 3 phase power converter, i have a 4kw rotary one its great.

New to this game but just thought I'd add that you could use a 3 phase inverter, and rewire the motor to work off 240v 3 phase. most 3 phase motors will rewire even if they say they wont. then you have speed control also. Just done this on my chipmaster and suds pump, works a treat!

 

[bgarvanman]

Yes,

I find single phase to three phase inverters an easy way to convert three phase machines to single phase power.

Just make sure that the 3 phase motor is a dual wound star / delta type and your away, the inverter providing 3 phase 220/240v power.

Available up to about 3kw,

dinnyb

 

[scarecrow]

I nearly had the same problem as jim I was going to buy a five horsepower three-phase compressor a few weeks ago for €350 which was a Steal. I was also thinking of putting the new motor on it but from reading some of the treads around here three horsepower is is about as high as you can go on one phase
I'm not very electrically minded can wire a plug and some other bits and pieces and that's about it I would be very interested in making a converter or inverter(whatever it is) any diagrams or instructions would be much appreciated

 

[shenion]

You can run more than 3HP on single phase. I think 3HP is about the limit on 13A.

My compressor has a 5HP motor, it runs on a 20A breaker.

Here is info on makeing a static phase converter: http://home.att.net/~waterfront-woods/Articles/phaseconverter.htm

 

[snowcat]

Here is the refrence I used when i built mine, It has everything in there, I think there was an issue with the way the caps were wired in on the contactor, but if you start geting problems il do me best to help. http://www.metalwebnews.com/howto/ph-conv/ph-conv.html

Edit, I used the link shenion had posted up also.. although through reading i found the rotary was the better option and not much more difficult to build.

 

[scarecrow]

Thanks guys I've been doing a little research as well and came up with these sites
http://www.metalwebnews.com/howto/phase-converter/phase-converter.html
http://www.laserfx.com/Backstage.LaserFX.com/Hobby/PhaseConvert.html
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
I read somewhere last night to run of 5hp compressor you would need a 8hp idler as you would be starting it under load
I'm sorry now I didn't buy compressor but I'll be keeping an eye out for a three-phase motor when I get one you'll be the first to know about it

 

[snowcat]

Thanks guys I've been doing a little research as well and came up with these sites
http://www.metalwebnews.com/howto/phase-converter/phase-converter.html
http://www.laserfx.com/Backstage.LaserFX.com/Hobby/PhaseConvert.html
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
I read somewhere last night to run of 5hp compressor you would need a 8hp idler as you would be starting it under load
I'm sorry now I didn't buy compressor but I'll be keeping an eye out for a three-phase motor when I get one you'll be the first to know about it

yep thats right scarecrow the power is lost because your only running at 2/3 of the power aprox, A 5hp will give you enouth power to run about 3.5hp max.