Leakage current tests
Leakage current tests
(OP)
During the static full-flux test, the stator windings were put through several full-current thermal cycle cycles that were quite severe. After that, the stator windings were subjected to resistance testing and leakage current testing. It was found that several of the stators exhibited unacceptable leakage current from the windings to the stator lamination stack.
The question is, did the leakage have anything to do with stator material? (we used unannealed Hyperco Fe-Co lams)
The question is, did the leakage have anything to do with stator material? (we used unannealed Hyperco Fe-Co lams)





RE: Leakage current tests
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RE: Leakage current tests
RE: Leakage current tests
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RE: Leakage current tests
Resistivity is actually pretty much the same for both annealed and un-annealed materials.
RE: Leakage current tests
If that's the case, then. speaking as a neophyte, it sounds very plausible that the anneal would change that behavior. I can sort of imagine that in an unannealed material, the magnetic flux getting discombobulated and shorted out, while an annealed material would have the flux sailing nicely through it.
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RE: Leakage current tests
http://www.metglas.com/products/magnetic_materials...
http://www.doiserbia.nb.rs/img/doi/1451-4869/2013/...
http://www.vptechnotron.cz/download/katalog2_en.pd...
Which all seem to support the notion that flux will be less for unannealed material
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RE: Leakage current tests
Do you do a bench mark test before you start the the thermal cycling?
Bill
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"Why not the best?"
Jimmy Carter
RE: Leakage current tests
Unanneal bothers me a bit since this material is not supposed to use this way.
RE: Leakage current tests
I’m guessing motor but I want to confirm.
Roughly what size motor?
I'm familiar with motor testing but I’m not familiar with a full flux test for motors that would put the windings through full current thermal cycles. Do you energize stator windings directly or do you use a loop around the core?
On transformers, a change in exciting current pattern (usually an increase) is supposed to be associated with a shift in the windings under mechanical stresses.
Exciting current is not typically measured for motor stator cores on its own. If the exciting current magnitude did increase I guess there is a small possibility that a gap has opened up if you have segmented laminations (for example 8 different segments around the circumference at one axial elevation of the vertical core).
Otherwise, I guess we might think about a really really severe core interlaminar insulation damage such that the resistive component of current (due to circulating currents thru shorted lams) becomes significant relative to the inductive component. To check for this, do a standard stator core test which checks for “watts loss” (watts per pound) and possibly look for hotspots on the stator bore by thermography during the test.
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(2B)+(2B)' ?
RE: Leakage current tests
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(2B)+(2B)' ?
RE: Leakage current tests