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Old 12-23-2011, 07:58 AM   #148
Beastly Adventurer
Joined: Jul 2008
Location: The great state of confusion
Oddometer: 4,313
Originally Posted by vtbob View Post
Does the insulation on the stator winding age? Would this aging cause shorted windings and over heating? Would these shorts cause gradual output voltage reductions...that could be measured as a precursor symptom?
Why would the stator insulation age / fail? Poor material used? Some type of contaminations? Vibration cause cracking? All good things to think about and get more info.
Has anyone really analyzed a failed stator?

All good questions .... If I were a gambler I woulf vote for the quoted item above... but it's just a guess.
IMHO, yes, insulative qualities do degrate with time/heat so at some point when you get a short between ajacent windings the situation is agrivated and feeds on its self till it self destructs. The time it takes for this to happen would likely be a function of ambient temperature, average speed of bike (more convective cooling at higher speeds, but then also higher current in the stator at higher speeds ... not sure which would predominate.... ) and then if bash plate was installed this would reduce the convective cooling ....

With the stator sitting inside the "counterbored" flywheel and not getting much of any oil bath cooling and sitting on top of the exhaus header it is a less than ideal situation for the stator....

One of the other guys on the forum was going to send me his failed stator unit, but I have not hear back from him...
If I get it I will try to see what I can figure out... but it may be difficult to figure out wether the insulative failure was the result of the failure or the cause of the failure or ... both ...?

One thing I've mentioned before is that if the copper used in the windings is a lower grade it would have a higher bulk resistivity and thus create more heat.

In terms of predicting failure ... if all three stator windings are at the same voltage (the voltage will vary with RPM) then likely the stator is good - if on the other hand one of the windings is at a lower voltage then likely that winding is failing ... A device could be designed that would plug in-line with the harness from the stator that would monitor/compare the voltages of the three windings and post an alarm if one winding started acting up.... In truth I'm not sure how much better that would be than just a simple voltage monitor...

JRWooden screwed with this post 12-23-2011 at 08:57 AM
JRWooden is offline   Reply With Quote