Rewinding a Generator

[petronila]

Hello All,

Some one wants to repair a low voltage Ac Generator insulating the same failed formed coils, I now this is not a good practice but the costumer wants to evaluate this possibility, some one with experience? pro and cont? thanks for the inputs

Carlos

 

[electricpete]

For large motors, sometimes a failed coil is "cut out".

It is important to evaluate the resulting unbalances.

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[ccjersey]

I had a repair shop investigate the problem with a 25kW 3 phase set that had residual on only one phase and wouldn't build up voltage. No obvious burned insulation or other problem, just quit under load (0verload???).

Turns out there was a short between phases at the lead end of the stator where the leads were spliced on and insulated. The short was reinsulated and the leads relaced and the whole stator cleaned baked and dipped etc. Still running fine, but it's only a backup so it has accumulated only a few hours in the 15 years since.

I would say that is likely to be an uncommon occurrence.

 

[edison123]

Hi Carlos

If the old winding was varnished and baked, then you cannot possibly take out the coils in reusable form.

If the old winding was unvarnished, what sort of ground insulation was there in these formed coils ? Can you remove the old coils withotu distorting the shape ? Is the turn insulation good ?

When we were starting up in 70's, we used to "re-insulate" these formed coils. We have been only rewinding with new coils for the past 20 years.

* Women are like the police. They can have all the evidence in the world and yet they still want a confession - Chris Rock *

 

[electricpete]

I think the only feasible repair if a coil is failed will be a cut out coil. (and that still needs evaluation).

Anyone agree / disagree?


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