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andymeyer
Joined: 31 Mar 2015 Posts: 54 Location: SW MI
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Posted: Sun Feb 26, 2023 4:28 pm Post subject: SD-8 Self Exciting via Z25L |
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I am setting up the regulator and components from Z25L for a self exciting SD-8 to support backup power for my second ignition and backup power for the aircraft E-Bus.
One option is to screw this stuff to an Aluminum plate and let it hang out in the air - another is to 3D print an enclosure for everything. Question is how much heat do I have to deal with and what's the fire risk of these components if I have it running full tilt (not likely in my configuration, but...)
I'm not seeing more than a watt from the resistors if my math is right. How much heat from the regulator and diode bridge?
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chaskuss(at)yahoo.com Guest
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Posted: Mon Feb 27, 2023 4:51 am Post subject: SD-8 Self Exciting via Z25L |
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The SD-8 produces power whenever it is moving. The faster it rotates, the more power it creates. The issue is shedding that power [which is converted to heat] when it isn't needed. So max heat is created at normal cruise power to max [2700] RPMs, when the unit's power is not required [normal operations]. That means you need max ability to shed heat 98% of the time. Better to keep the voltage control device out in the open on a large heat sink [aluminum plate]
Classic British motorcycles use this same sort of alternator and voltage control. Check out the large aluminum plates used to mount the drivers footpegs in the photo linked below [1975 Norton 850 Commando Mk III] The voltage control devices [Zener diodes] are mounted to the back side of these plates
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user9253
Joined: 28 Mar 2008 Posts: 1921 Location: Riley TWP Michigan
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Posted: Mon Feb 27, 2023 8:32 am Post subject: Re: SD-8 Self Exciting via Z25L |
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It seems that you are saying that the voltage regulator for the SD-8 is
a shunt type. Is there any documentation to support that?
Most modern voltage regulators for permanent magnet alternators are
the switching type. They open the output for part of the AC cycle. The
power produced is determined by the connected load, provided that the
permanent magnet alternator is spinning fast enough to maintain the voltage.
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_________________ Joe Gores |
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nuckolls.bob(at)aeroelect Guest
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Posted: Tue Feb 28, 2023 6:21 am Post subject: SD-8 Self Exciting via Z25L |
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At 06:28 PM 2/26/2023, you wrote:
Quote: | --> AeroElectric-List message posted by: "andymeyer" <meyerkc135(at)gmail.com>
I am setting up the regulator and components from Z25L for a self exciting SD-8 to support backup power for my second ignition and backup power for the aircraft E-Bus.
One option is to screw this stuff to an Aluminum plate and let it hang out in the air - another is to 3D print an enclosure for everything. Question is how much heat do I have to deal with and what's the fire risk of these components if I have it running full tilt (not likely in my configuration, but...)
I'm not seeing more than a watt from the resistors if my math is right. How much heat from the regulator and diode bridge? |
This isn't a 'fire risk' . . . it's a risk of
regulator failure. The SD-8 stock regulator is
a 4-component, bridge rectifier, SERIES switch
configuration that rejects something on the order
of 30 watts at full load.
The power-path components depend on thermal
conductivity of the potting compound for heat
rejection. The rectifier/regulator's service
life is tied to optimizing thermal management.
I've been considering an instrumented
thermal study on this device but that's
pretty far down on the to-do list right
now.
B&C installation instructions should be
followed . . . when in doubt, calling
B&C directly with such questions is a far
more reliable than consulting folks
who have no personal knowledge of the
product construction and performance.
They're really nice and helpful folks
who enjoy hearing from their customers.
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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user9253
Joined: 28 Mar 2008 Posts: 1921 Location: Riley TWP Michigan
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Posted: Fri Mar 03, 2023 12:24 pm Post subject: Re: SD-8 Self Exciting via Z25L |
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I asked B&C about their voltage regulators for permanent magnet alternators. Below is their reply:
The PMR1C is indeed a switching series regulator.
(The) AVC1 regulator, designed as a replacement for the PM Ducati regulator
used on Rotax 912/914 engines, is (in contrast) a shunting device.
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_________________ Joe Gores |
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