How to meg a 110/220 single phase AC motor

[markba633csi]

If you happen to lose track of which wire goes where I can help you re-identify them- a couple simple ohmmeter checks is usually all it takes

 

[ltlvt]

If you happen to lose track of which wire goes where I can help you re-identify them- a couple simple ohmmeter checks is usually all it takes

If you happen to lose track of which wire goes where I can help you re-identify them- a couple simple ohmmeter checks is usually all it takes

This would be greatly helpful and greatly appreciated. No color and in some case no insulation left on the wires. I have not traced them back to the coils they are connected to yet. Trying take it slow to help control any further damage. Thanks for the reply.

 

[ltlvt]

Here is a you tube video that deals with single phase motors. BTW this is the megger that I have, and it works great. Being this is a fan motor for HVAC they always have the capacitors mounted remotely from the motor so as den-den has stated you are not supposed to megger the capacitor. I will be going all the way back to the termination of leads on each coil so now comes the hard detective work.

 

[luap]

luap : could you please explain what you mean in "relieve" (A Megger might "relieve" a shorted winding but there isn't much between wires in a coil?)

Some repairmen use a Megger to create an arcing effect (or heat) to fix a shorted winding...The copper enameled wire windings are close together ,separated by the existing coating on the wire then the insulating varnish ..so the arcing causes the varnish to run into the shorted section.

Transformers can also be repaired in similar manner but low voltage would do all right .
Your cooking it to correct the moisture content an etc . An oven will also do.

I think there is a treatise on this subject?

Many stories of natural disasters .
waterlogged pumphouse etc .
an they had to get the pumps back online.
Only to take the electric motors to the shop or oven to dry them out (The moisture .) ........

 

[ltlvt]

Some repairmen use a Megger to create an arcing effect (or heat) to fix a shorted winding...The copper enameled wire windings are close together ,separated by the existing coating on the wire then the insulating varnish ..so the arcing causes the varnish to run into the shorted section.

Transformers can also be repaired in similar manner but low voltage would do all right .
Your cooking it to correct the moisture content an etc . An oven will also do.

I think there is a treatise on this subject?

Many stories of natural disasters .
waterlogged pumphouse etc .
an they had to get the pumps back online.
Only to take the electric motors to the shop or oven to dry them out (The moisture .) ........

Thank you verry much for explaining that to me. Now I understand. I am just a hobbyist but always eager to learn. I managed the skilled trades dept for GM for many years and was a skilled tradesman before, so I have been close to all aspects of skilled trades my entire life. Now that I am retired, I realize most of the trades are in my DNA. Again, thanks for the response.

 

[luap]

Thank you verry much for explaining that to me. Now I understand. I am just a hobbyist but always eager to learn. I managed the skilled trades dept for GM for many years and was a skilled tradesman before, so I have been close to all aspects of skilled trades my entire life. Now that I am retired, I realize most of the trades are in my DNA. Again, thanks for the response.

New to the( Forum )an still trying to digest what is going on here . Inventing a new world, I think we have done that here ?........

 

[ltlvt]

As I promised earlier here is the update on the motor. Being 70 years old and subject to wandering around in the shop trying to remember what I was fixing to do I thought it would be a good idea to make a list of steps to follow to keep me inline on the motor . So here are the first of the steps and the status of each.

Step 1 Vacuum the inside of the stator and all leads. - Complete

Step 2 Verify with DVOM there were no shorted leads and measure resistance on each. - Complete

Step 3 Document with photos the location of all leads their terminals. -Complete

Step 4 Check each lead with Megger to ground -Complete but failed every lead except the start leads.

Step 5 Blow inside all groves of stator on both ends with canned air. -Complete (should have seen all the lint and dust that came out.)

Step 6 Re-Check each lead with Megger -Complete and all leads checked good beyond the max range of 1,000 megaohms. Which is the best you can get. I verified my megger using one brand new 2 hp Baldor motor I have and a just rewound 2 hp Reuland motor that I had rewound by Wiemsco . So now I have insured the light is green to go further towards repairs.


Step 7 will be to permanently mark each lead and where they are terminated before replacing the ones that are beyond salvaging. I do think marking and a hand skeched schematic for myself will be of value to help me remember. So for now here are a few pictures before I start snipping wires.

 

[markba633csi]

By all means mark them- I always do
Saves a lot of work later

 

[ltlvt]

Mark, I have decided to take the lower risk way out. The old wires are still intact and when I tried to get solder to stick to them it was a losing battle. It may be the solder that I am trying to use. It is a 60/40 wire made in China of course with its matching flux but it will absolutely not bond with either the old, oxidized copper or brand-new stranded copper wire. So, I opted to just remove all the brittle insulation from the old wires and use the liquid tape shown in the picture. It is a slow process of brushing on a coat and letting it almost cure and then applying another coat. I expect it to take at least 4 coats on each wire maybe even more. The wires that I can slip shrink tube over the dried liquid tape will also get shrink tube. In addition, where the wires join the windings, and the windings will all get the RED high temp varnish brushed on out of a bottle. I know this seems to be a lot of work over just buying a new single-phase motor but one of this size will cost at least $300 and would only have a single shaft where this one is a dual shaft. Besides I prefer to resurrect Old than to buy New. I have owned this motor for over 37 years myself and it was used when I got it, so it is surely at least Vintage. Marathon made this motor in Wisconsin and now Marathon resides in India. So, I can at least boast Made in the USA...

 

[markba633csi]

I've had experience of impossible to solder stranded wires. The problem is a thin layer of corrosion, developed over many years, and hard to remove.
The liquid tape option is fine, though time consuming