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1. 02:05 PM - Re: Re: Thermocouples: grounded or ungrounded (Paul Eckenroth)
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| Subject: | Re: Thermocouples: grounded or ungrounded |
[image: IMG-1229.jpg]
Bob
I agree with what you are saying concerning the ideal method of monitoring
the coils. However I need to work with what I have and I don't think I can
monitor 12 individual coils with the tools at my disposal. I do plan on
using your idea of the rotary switch and I appreciate the schematic. I
thought all might be interested in a picture of the stator after removal.
The one coil suffered catastrophic damage with the phenolic spacer
completely destroyed by the heat. I have machined the case to allow more
ventilation and will add two blast tubes directly at the coils. And hope
for the best.
Paul
I did check with GRT and their EIS/ EFIS cannot read thermocouples except
through the 4 or 6 EGT and CHT inputs.
On Thu, Jul 7, 2022 at 3:22 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> The most important temperature readings will be of the stator.
>
>
> yeaaahhh . . . sort of. Temperature numbers of the stator
> stack adjacent to mounting bolts will be greatly
> influenced by heat transfer to the crankcase.
>
> We know that the stator failures are generally limited
> to one pole. How do the wires look on remaining poles?
> To precipitate this 'isolated' failure suggests a thermal
> runaway event where the resistance of copper rises with
> temperature which in turn, increases energy dissipated in
> the wires. I.e. a positive feedback for temperature
> excursion.
>
> To catch a pending failure suggest a need to monitor
> each winding . . . unless field experience shows that
> failures are concentrated.
>
> In any case, other temperatures around the system's
> components may be interesting data but I'm skeptical
> as to their ability to flag impending failure any
> one coil.
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
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