Using old stator housing (iron rings) as transformer core? Possible?

Thread Starter

RogueRose

Joined Oct 10, 2014
374
I have an old stator from a motor I took apart and it is made of many rings of steel, welded in a few places to keep it together, similar to how transformers are welded.

It obviously has the spaces to hold the windings inside the core so IDK if those will pose a problem or not and I'm sure I could put something inside it like a solid steel rod and weld it in place (could probably get near perfect fit). I could also cut off the "legs" that make the hole. The size is to big for one transformer so I would use it in 1/5's to 1/3's to make it reasonable, but still large.

I was considering making a variac with this if this is possible as I have the wire to make one.

stator1.jpg stator2.jpg
 

Alec_t

Joined Sep 17, 2013
10,429
Looks ok as the basis of a toroidal transformer. If you cut it into 3 or 5 you'd have incomplete magnetic circuits and hence very poor transformer efficiency.
 

Thread Starter

RogueRose

Joined Oct 10, 2014
374
Looks ok as the basis of a toroidal transformer. If you cut it into 3 or 5 you'd have incomplete magnetic circuits and hence very poor transformer efficiency.
No, I think you mis-understand what I meant (my fault, poor description). The stator is long (many stacked plates - maybe about 200). I was thinking of using 40 - 66 of them instead of the entire length as this is about 7.5" long and about 8" diameter
 

crutschow

Joined Mar 14, 2008
23,484
That should work as long as you have sufficient turns to avoid core saturation.

But you don't need to add anything to the center of the core, you just wrap the wires around the stator like a toroidal transformer.

How would you vary the variac voltage?
 

shortbus

Joined Sep 30, 2009
7,074
Some motor stator laminations aren't made from the same grade of steel as real transformer grade steel. So saturation could be different.
 

Thread Starter

RogueRose

Joined Oct 10, 2014
374
That should work as long as you have sufficient turns to avoid core saturation.

But you don't need to add anything to the center of the core, you just wrap the wires around the stator like a toroidal transformer.

How would you vary the variac voltage?
I'm not quite sure I know exactly what you are asking but what I would do is do a single pass first coil winding - then insulation, then a second layer of the same wire, which should create an isolation transformer. Then sand down the top of the wire in one area of the of the winding (outer or inner part of the top of the winding. Then have a graphite contact sweep across the sanded area giving the difference in voltage.
 

GopherT

Joined Nov 23, 2012
8,012
I'm not quite sure I know exactly what you are asking but what I would do is do a single pass first coil winding - then insulation, then a second layer of the same wire, which should create an isolation transformer. Then sand down the top of the wire in one area of the of the winding (outer or inner part of the top of the winding. Then have a graphite contact sweep across the sanded area giving the difference in voltage.
Or, you could buy a Variac for about $50.
 

GopherT

Joined Nov 23, 2012
8,012
Also, the laminations are just that, laminations. There should be a carefully deposited magnesium oxide layer between each layer, or if it is old, craft paper. No conductivity between layers.

The silicon-steel laminates should be free from oxidation. It looks like it is covered with blisters of rust.

Check the conductivity between layers (start from outside and work one probe towards the other side to see if you get any continuity. Then repeat for the other end cap. Any conductivity will cause eddy current heating and lower magnetic saturation.
 

shortbus

Joined Sep 30, 2009
7,074
Check the conductivity between layers (start from outside and work one probe towards the other side to see if you get any continuity. Then repeat for the other end cap. Any conductivity will cause eddy current heating and lower magnetic saturation.
Most motor stators have at least one row of weld bead linking all of the lamination's together, so that may not work.
 
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