Winding Varnish / Electrical Insulation Coating for Motor Repair?

I have an MXUS 4503 on the SB Cruiser trike that needs a bit of rework. (I've already welded a new end to the axle that had broken off)

Pics of the insides at the end of the post.

First, it has a fixable short between one of the "blue" phase windings and the stator lamination; I've temporarily fixed that by inserting plastic shims (bits of ziptie) between the winding and the face of the lamininations in the area that tapping the windings while running an isolation tester at 250v indicated a problem.

Second, I need to replace phase wires with something signficantly better than 18g but with very good insulation that has good thermal resistance to melting or softening.


I've poked around a number of threads discussing various varnish types and motor repair; some have links that still work, and I've found a number of different types of brush on, spray on, etc., insulating varnish. They all appear to be very similar, as do most of the ones discussed previously. But before I buy one, I would like opinions from those that have used similar types.

--is it likely that these (see links below) will flow down into the windings, and get between the stator and windings, to help create better insulation that what's there, potentially fixing this motor in a more permanent way (without rewinding, which is simply never going to happen)?



Secondarily, for the phase wires, I've been considering using magnet wire out of an old microwave oven transformer, or the transformer out of my first (dead) welder. But i'd also wnat to use something additional for insulation between each of the phases, and between the phases and the axle/bearing/etc. I suspect Kapton tape would be sufficient for this, as long as the temperatures can be kept down (with the 18g wire I could fit (that failed) temperatures witin hte wire jacket just outisde the axle were up to about 125-130F with 100A phase currents on the SFOC5 controller.

I need something reliable, that can handle 150-200A+ phase currents, for short bursts at least (a few seconds at a time, repeatedly over a few minutes of rding on my commutes, and longer times on other trips, with longer burst durations if carrying heavy cargo or a trailer full of dog, etc.

So...suggestions? Thoughts?

I'm looking to do this stuff in the next several days, depending on when the stuff will arrive here, once I have enough useful responses.

Kapton links first, then varnish:

https://www.amazon.com/Mil-Kapton-Tape-Polyimide-Yds/dp/B006ZFQNT6

https://www.amazon.com/Mil-Kapton-Tape-Polyimide-yds/dp/B006ZFNB2I

https://www.ebay.com/bhp/kapton-tape


https://www.amazon.com/dp/B008OA7CAE?psc=1&pf_rd_p=bb9788eb-24d0-484f-bb96-c8eca0708597&pf_rd_r=7VT9MQZ3KSEK8AWYH0JG&pd_rd_wg=5z5jI&pd_rd_i=B008OA7CAE&pd_rd_w=PH8KU&pd_rd_r=d328b2b1-00f8-4903-8951-a78f1ecdc165&ref_=pd_luc_rh_crh_rh_sim_03_01_t_img_lh

https://www.amazon.com/IEC-60317-50-Ed-1-0-Specifications/dp/B000Y2SGZ0/ref=sr_1_2?keywords=winding+varnish&qid=1552194033&s=gateway&sr=8-2

https://www.amazon.com/MG-Chemicals-GLPT-Insulating-Varnish/dp/B008OA7DDK/ref=sr_1_1?keywords=winding+varnish&qid=1552194033&s=gateway&sr=8-1

https://www.amazon.com/dp/B0034D1ZCM?psc=1&pf_rd_p=c35a81db-c1c9-4121-b93f-97ef6cbb19f8&pf_rd_r=7VT9MQZ3KSEK8AWYH0JG&pd_rd_wg=5z5jI&pd_rd_i=B0034D1ZCM&pd_rd_w=ZOuYx&pd_rd_r=d328b2b1-00f8-4903-8951-a78f1ecdc165&ref_=pd_luc_rh_crh_rh_sbs_02_04_t_img_lh

https://www.ebay.com/itm/MG-Chemicals-4228-225ML-Red-GLPT-Insulating-Varnish-225ML-Bottle/331529483474?epid=9011367709&hash=item4d30b274d2:gOMAAOSwqu9VLBIl

https://www.ebay.com/itm/MG-Chemicals-4228-55ML-Red-GLPT-Insulating-Varnish-55ml-Bottle-NEW/231070150546?epid=11024539531&hash=item35ccdaaf92:g:13wAAOxygLxSVGYX

https://www.ebay.com/itm/MG-Chemicals-4228-1L-Red-GLPT-Insulating-Varnish-1-Liter-Bottle/251918313995?epid=659490270&hash=item3aa7806a0b:g:mFUAAOSwBahVLBM5

https://www.ebay.com/itm/MG-Chemicals-4228-55ML-Red-Insulating-Varnish-55-mL-Bottle/183674349887?epid=18012068013&hash=item2ac3d8293f:g:-dsAAOSwtM9cXBks:sc:ShippingMethodExpress!85051!US!-1

https://www.ebay.com/itm/GC-ELECTRONICS-10-9002-A-ANTI-OXIDATION-RED-INSULATING-VARNISH-2FL-OZ-BOTTLE/401087906220?epid=2254360029&hash=item5d62b3c1ac:g:NKoAAOSwr7ZW5b30:sc:USPSFirstClass!85051!US!-1

https://www.ebay.com/itm/MG-Chemicals-4226-55ML-Super-Corona-Dope-High-Voltage-Insulating-Varnish/120798757392?hash=item1c202ac210:g:RUAAAOSw-31bavzY

https://www.ebay.com/itm/MG-Chemicals-4228-55ML-Red-Insulating-Varnish/111653147651?hash=item19ff0bd403:g:ONEAAOSwwstbav74

https://www.ebay.com/itm/MOTOR-WINDING-TRANSFORMER-BARE-WIRE-INSULATING-VARNISH-SPRAY-REPAIR-COATING-CAN/152021663167?hash=item2365327dbf:g:YykAAOxyOypSWx3F






More details, pics, etc
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1450682#p1450462

It's a gamble but could work.. the varnish i have used soaked really well into the winding, i heated the entire stator to 40 deg C to help with the flow. It can be soaked several times.

Question is only if you will get it to the correct spot, thick enough..
Other question is that the heat resistance of the varnish i used was not comparable to the original coating, it softened even though it was within temp spec. Product i used was Ultimeg 2000/372, 180 degC temp varnish

I'd try

If going with used magnet wire just be absolutely sure of no shorts due to insulation scrapes and forget about insulation between the phases, halls, and temp sensor wires (yeah, do those with thinner magnet wire too). Being a one time permanent mod I'd spring for new wire as It's much easier to work with and get into a nice tight smooth bundle. The magnet wire varnish already insulates every strand, (eg the windings have no extra insulation between phases) and the whole reason to do it that way is to not waste limited space through the axle with unnecessary insulation.

Tips:

-By far the hardest most time consuming part for me is making the ends of each strand bare and join them with solder into each phase first. Measure resistance to be sure each strand has continuity.
-Stagger the ends of the phases when forming the complete bundle to go through the axle, so you end up with a tapered end to send through.
-Completely enclose the end you're sending through with the double heat shrink to avoid scraping while push/pulling it through. The point should be a tough soldered bundle of strands for one of the phases covered in double shrink...You'll grab it with pliers to pull through to help make the bend at the inside end of the tunnel (thus the push/pull at the same time method)
-Clean the axle tunnel and file/sand down any sharp edges to avoid cuts in the shrink.
-I used silicone as lubricant
-

John in CR said:

-Stagger the ends of the phases when forming the complete bundle to go through the axle, so you end up with a tapered end to send through.
-Completely enclose the end you're sending through with the double heat shrink to avoid scraping while push/pulling it through. The point should be a tough soldered bundle of strands for one of the phases covered in double shrink...You'll grab it with pliers to pull through to help make the bend at the inside end of the tunnel (thus the push/pull at the same time method)
-Clean the axle tunnel and file/sand down any sharp edges to avoid cuts in the shrink.
-I used silicone as lubricant

Click to expand...

Thankfully, after my axle repair (from the last time it broke), I don't have an "axle tunnel" to deal with (since that's part of why it broke I left that "feature" out). I simply have a semicircular space between the bearing ID and the axle flats (which I extended thru the bearing hole); one side is a larger open area than the other at present, by a small amount.

So I don't need to worry about any of that stuff. I can simply wrap the bundle(s) in Kapton tape (which is very thin), and then tie the bundles down to the axle inboard of where the bearing will be once the cover is in place. This will be a lot thinner than heatshrink, leaving me at least a bit more volume for conductors.

I would definitely prefer to use at least a layer of Kapton between the phases, to doubly ensure there "can't" be a short between them in the event of overheating (since the Kapton should be good for a lot hotter than the winding insulation). Since Kapton can be fragile, I might see how thin a tape I can get Teflon in, as an outer jacket for the whole thing. (so it would end up something like TKT insulation does).

Any other opinions on which varnish might be more applicable to this type of repair?

At the moment, I have these in my cart, and will just get all three if not.

1 Mil Kapton Tape (Polyimide), 3" x 36 yds
https://www.amazon.com/gp/product/B007GCNAB6/ref=ox_sc_act_title_1?smid=A1RYF7WY9L3HL5&psc=1

MG Chemicals Super Corona Dope, 55 ml Liquid Bottle with Brush Cap Applicator
https://www.amazon.com/gp/product/B008OA7CAE/ref=ox_sc_act_title_4?smid=ATVPDKIKX0DER&psc=1

MG Chemicals 4228-55ML Red Insulating Varnish, 55 mL Bottle
https://www.amazon.com/gp/product/B008OA7DDK/ref=ox_sc_act_title_5?smid=ATVPDKIKX0DER&psc=1


Maybe also add this (or similar) as a protective "jacket" around the wires to prevent damage to the kapton.

1" x 11yds PTFE Adhesive Tape PTFE Coated Fabric Teflon Tape
https://www.amazon.com/gp/product/B07BL1MJ47/ref=ox_sc_act_title_1?smid=ALM0AUUTE78RO&psc=1

So I ordered the above stuff, and the Kapton tape should be here today; the "CoronaDope" should be here tonight or tomorrow morning, and then I can try coating the windings with that, in the areas where I had to push them up away from the stator to remove the isolation fault.


BTW, I pulled out the old welder transformer, and it has 10g magnet wire on one side, and 14g on the other side. More on that and the repair itself here:

https://www.endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1451436#p1451436

Don't know if it will help, but have you seen.. or used the liquid electrical tapes? I haven't used them, but always
wondered how tough they were. Might be thick enough to fill in a void?



Theres also Plastidip, which I have used, and is pretty tough,.. good for painting on surfaces.

https://www.google.com/search?hl=en&biw=1680&bih=989&tbm=isch&sa=1&ei=YLOJXLnaKKXMjwSMq6P4CQ&q=liquid+electrical+tape&oq=liquid+electrical+tape&gs_l=img.1.0.0l2j0i5i30l2j0i24l6.98984.104463..107439...0.0..1.725.7168.3-2j10j2j1......1....1..gws-wiz-img.......0i7i30j0i7i5i30.sXeC2X-l8xM#imgrc=_

Some of those things may not be good at high temperatures. Motor windings can get very hot.
Hard to find, but industrial grade Class H motor varnish is the real deal.
I've used exhaust system paint before, as well as some old marine varnish lying around the garage. The wood varnish seemed to hold up pretty well long term but sure stank the first few times the motor got hot.

APL said:

Don't know if it will help, but have you seen.. or used the liquid electrical tapes? I haven't used them, but always
wondered how tough they were. Might be thick enough to fill in a void?
<snip>
Theres also Plastidip, which I have used, and is pretty tough,.. good for painting on surfaces.

Click to expand...

Unfortunatley neither of those will work for either of the repairs, for more than one reason.

--They're nowhere near thin enough to wick down into the windings/stator to fix that.

--They aren't able to withstand the heat the windings themselves will see, without at least softening, if not actually melting thru. If the phase wires got hot enough to melt Teflon and the plastic jacket, and electrical tape and Gorilla tape (where they were secured to the stator supports inside), they'll soften or melt Plastidip or Liquid Electrical Tape enough to allow the wires to move within it, and potentially short against whatever they're near enough to touch if pressed against them.

Something else too but I forgot while typing the above.

They *are* useful for filling up and "sealing" the wire entry/exit on axles, but my axle doesn't have the usual thru-hole; the wires run along the surface of it (previously on the flats, now will be in grooves on those flats).

fechter said:

Hard to find, but industrial grade Class H motor varnish is the real deal.
I've used exhaust system paint before, as well as some old marine varnish lying around the garage. The wood varnish seemed to hold up pretty well long term but sure stank the first few times the motor got hot.

Click to expand...

I ran across some places that appear to sell the varnish, but not in small amounts, so would be well out of my budget. I also don't think they sell to individuals (no regular sale page).

I almost bought a spray can of the red engine paint, but it was a budget choice between that or the CoronaDope and the other Red Electrical Varnish, so I went with the two instead of the one, especially since they are both brushon and thin enough to easily control where they go (for the most part). And I know the CoronaDope will handle the electrical insulation needed, and will probably handle the heat.

I thought about using the polyurethane I have, that I used on parts of the SB Cruiser's wooden bits, but I'd rather fix it right once, than have to figure out how to remove stuff that doesn't work, and redo it.

THe repair is "complete" and appears to be working correctly, passes isolation test at 250v and 500v axle to phases. Pics and stuff over here:

https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1451710#p1451710

https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1451710#p1451708

https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1451710#p1451702