Single Phase Induction Motor Winding

[novellsuse]

Hi,
Wondering if someone here could help me out. I currently have an AC induction motor that is a 3450 rpm(2 pole), 1 1/2HP, 115/230V split run winding & cap. start winding. My total run winding resistance is 1.1 Ohm. The wire the factory used for the run winding is 16ga aluminum wire. The 2 poles are concentric wound. What I want to do is replace the run windings with all copper 16ga wire. I understand that the copper has much less resistance than Aluminum. My goal is to have a motor that runs cooler and has a higher service factor. The concentric windings are wasteful for efficiency. I want to wave wind the 2 poles of the motor. The concentric winding pattern that the factory used, has way too many wires horizontally out of the core slots. These wires...MANY feet are not in the direct magnetic field like the ones in the vertical stator core slots. Can I wave wind the two poles with the amount of copper wire until it adds up to the same 1.1 Ohms for the original winding? Also...what would happen if I used alittle less? Say .8 Ohms. When I wave wind each pole, do I wind them exactly the same way, or do I wind each one from opposite directions? Anyones help would be greatly appreciated!....Thanks, Doug (DN2772_1@webtv.net)

 

[SteveKW]

Going from aluminum to copper you typically go one size smaller!

Going to a better insulation class may give a better SF and would increase the life of the windings.

As for changing the windings to concentric, I would think playing with the run cap to change the power factor would be an easier and quicker way to squeeze a few more pennies off the electric.

I wonder if just going up to the next size HP motor and adjusting the run cap would be an easier way to accomplish your goals?. You would gain your SF and the motor would run cooler!

 

[UKpete]

2-pole motors always have large end-windings, regardless of winding configuration. It's one of their main disadvantages.

Concentric windings are the norm because they can be machine inserted, but if you are redesigning/rewinding there is no advantage to concentric windings, you can use wave (or lap, which has the same performance). However, repair shops will always copy wind unless you can design/specify an alternative. BUT - you cannot just wind until a target resistance is met as you suggest. Instead you have to calculate the number of turns required for a given voltage and number of slots. If you want to improve the performance of this machine, some motor design knowledge will be required.

Also with hand winding the cost of the wire is relatively small, so use copper and get as much in the slot as you can - it will bring the losses down. Polyester grade 2 is a good choice, it is class H which will give you a very healthy SF.