1800 vs 3600 RPM for phase converter

I recall from various discussions here that 1800 RPM motors were preferred over the higher speed ones when making a phase converter. I picked up a 3 HP Baldor at a factory closing today for $10 with the intent of making a phase converter, and it's 3600 RPM. Why are the lower RPM motors preferred?

Source for inexpensive run capacitors?

RWL

Reply to
GeoLane at PTD dot NET
Loading thread data ...

they are quieter. Otherwise a 3600 RPM motor will do just fine.

Try

formatting link

-- all ebay searches in one quick page.

i
Reply to
Ignoramus28617

I think the size of the motor is the key. A three hp 3450 rpm motor is smaller than a three hp 1750 rpm motor.

For run caps try your electric company or whoever maintains the street lights.

Dan

Reply to
dcaster

Dan sez: "For run caps try your electric company or whoever maintains the street lights"

Also try any HVAC outlet. They usu. have a good selection of run caps and potential relays.

I think the size of the motor is the key. A three hp 3450 rpm motor is smaller than a three hp 1750 rpm motor.

.

Dan

Reply to
Robert Swinney

I have been told that a 1750 rpm motor was 4 pole and 3600 rpm was 2 pole. Thus making the 1750 rpm a better candidate, because it had more copper in it to generate the third leg.

Richard W.

Reply to
Richard W.

True. But I'm wondering.....

The kinetic energy energy of a rotating body is a function of the square of the angular velocity. Thus a flywheel of n kilograms on a 3600 rpm motor will have 4x the energy of the 1800 RPM one.

That sounds relevant...

Reply to
David Lesher

From my experience it's down to the noise; the cooling fan in my 2 pole

3000RPM motor (50Hz over here) was so noisy that I pulled it out and fitted a 6" enclosure fan (Muffin fan) on the end case instead, it's now tolerably noisy although the motor itself is still noisier than a 4 pole would have been. Aside from that, the motor works well as an idler. Martin
Reply to
Martin Whybrow

It may be, but you have 2 legs running the motor to generate the third leg on both motors. It not just idling under load, it's generating the third leg. So it would seem that a 4 pole motor would be better under higher loads.

Richard W.

Reply to
Richard W.

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.