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nuckolls.bob(at)aeroelect
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 Posted: Mon Sep 06, 2010 11:52 am Post subject: Cooling Jab 3300 PM Alternator |
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At 07:57 AM 9/6/2010, you wrote:
| Quote: |
<gordonrsmith921(at)yahoo.com>
'lectric Bob wrote:
"Your main alternator is rated for 22A intermittent (which you could
probably boost to continuous duty with some well considered cooling)."
How is this to be accomplished? Cooling air to the Rec/Reg or to the Alt
coils mounted to the back of the engine or both?
|
Perhaps both. But the primary concern is for
alternator windings. You can always go to a more
robust rectifier/regulator (John Deere?).
It would be a very interesting and useful experiment
to do some flight testing on temperature rise for
this alternator on the as-installed engine. We don't
know what limits the ratings given by Jab. Wire
temp limits? Semiconductors in R/R?
If the windings are similarly disposed about a
magnet bearing flywheel like the Rotax 912, then
cooling the coils would not be easy.
You could thermocouple the windings and do some
full load testing. I can't imagine anyone winding
the aircraft alternator with wire insulated at
less than Class H temperatures (180C max hot spot).
If we were sure that the wires were not being
abused, the beefing up the R/R might produce a
much more robust system. It's doubtful that
Jab will share the information even if they
know it.
Bob . . .
Bob . . .
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Mon Sep 06, 2010 6:50 pm Post subject: Cooling Jab 3300 PM Alternator |
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Bob, all, mention is made of the John Deere rectifier/regulator as a substitute for the Jabiru unit, however, as I recall, the JD unit is rather pricey, too. Has anyone investigated the Harley Davidson rec/reg? Can be had for at least two output levels and they're relatively inexpensive at $35 to $50. Just a thought.
Rick Girard
On Mon, Sep 6, 2010 at 2:48 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
At 07:57 AM 9/6/2010, you wrote:
| Quote: | --> AeroElectric-List message posted by: "Gordon Smith" <gordonrsmith921(at)yahoo.com (gordonrsmith921(at)yahoo.com)>
'lectric Bob wrote:
"Your main alternator is rated for 22A intermittent (which you could
probably boost to continuous duty with some well considered cooling)."
How is this to be accomplished? Cooling air to the Rec/Reg or to the Alt
coils mounted to the back of the engine or both?
|
Perhaps both. But the primary concern is for
alternator windings. You can always go to a more
robust rectifier/regulator (John Deere?).
It would be a very interesting and useful experiment
to do some flight testing on temperature rise for
this alternator on the as-installed engine. We don't
know what limits the ratings given by Jab. Wire
temp limits? Semiconductors in R/R?
If the windings are similarly disposed about a
magnet bearing flywheel like the Rotax 912, then
cooling the coils would not be easy.
You could thermocouple the windings and do some
full load testing. I can't imagine anyone winding
the aircraft alternator with wire insulated at
less than Class H temperatures (180C max hot spot).
If we were sure that the wires were not being
abused, the beefing up the R/R might produce a
much more robust system. It's doubtful that
Jab will share the information even if they
know it.
Bob . . .
Bob . . .
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