Today's Message Index:
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1. 09:54 AM - Re: Is there a switch configuration that will do this? (user9253)
2. 11:54 AM - Re: Re: Is there a switch configuration that will do this? (David Carter)
3. 12:49 PM - Re: Dual alternators (Peter Pengilly)
4. 01:15 PM - Re: Re: Is there a switch configuration that will do this? (Robert L. Nuckolls, III)
5. 01:27 PM - Re: Dual alternators (Robert L. Nuckolls, III)
6. 02:10 PM - Re: Re: Is there a switch configuration that will do this? (David Carter)
7. 02:12 PM - Re: Dual alternators (Kelly McMullen)
8. 09:34 PM - Re: Dual alternators (Robert L. Nuckolls, III)
9. 11:07 PM - Re: Dual alternators (tiyaverma)
10. 11:10 PM - Re: Dual alternators (tiyaverma)
Message 1
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| Subject: | Re: Is there a switch configuration that will do this? |
You need a DP3T ON-ON-ON switch.
Mouser and Digikey and others sell them.
https://www.mouser.com/Electromechanical/Switches/Toggle-Switches/_/N-5g2jZ1yzvvqx?P=1z0z2o3Z1z0z28f
https://www.digikey.com/en/products/filter/toggle-switches/201?s=N4IgjCBcpgzADFUBjKAzAhgGwM4FMAaEAeygG0RYAWeWAdgE4QBdIgBwBcoQBlDgJwCWAOwDmIAL5EATLACsSEKkiZchEuUoAOafABseluy6ReAkeKkgAtNMXKBAV3WlIFBcwlW7bkABEABVgAFRYJIA
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=502430#502430
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| Subject: | Re: Is there a switch configuration that will |
do this?
>> You need a DP3T ON-ON-ON switch.
Joe - thank you, it appears that would work electrically. It took me a few
minutes to decipher the actions of this switch, but I got there.
However, I have not yet found one in a form factor that would match the
rest of the standard toggles in my panel. I may have to just live with two
switches. It's not the end of the world, but it's not as elegant.
Thanks!
---
David Carter
david@carter.net
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| Subject: | Dual alternators |
In Diamond twins one regulator is the master and has the job of
balancing the alternators.
I=99m not actually sure how it achieves that, but works well most
of the time.
The regulators are provided by the engine mfrs (Continental or Austro).
The G1000 instrumentation systems use hall effect sensors to detect the
output of each alternator.
The regulators use a different sensor to do their job.
Can result in the G1000 saying the loads are unbalanced, which makes
pilots unhappy =93 although voltage is always good.
I have spent a lot of time troubleshooting, reloading G1000 software and
other stuff to cure what seems to be an imaginary problem.
Peter
From: owner-aeroelectric-list-server@matronics.com
<owner-aeroelectric-list-server@matronics.com> On Behalf Of Robert L.
Nuckolls, III
Sent: 17 June 2021 18:21
Subject: Re: AeroElectric-List: Dual alternators
I've imagined, but never tested, that running two alternators that
are feeding a single battery bus would be dominated by current from
one of the alternators.
My reasoning is that regardless of how closely the charge systems
are matched, small variations would result in a slightly higher
output voltage on one of them. This would then result in an even
lower output from the lower voltage output charge system,
which would reduce its current contribution.
Yes, until system loads exceeded the capacity
of the alternator with the higher set-point. The
bus voltage sags allowing the lower set-point
alternator to wake up and begin to support the
load.
This is what happens with a B&C standby alternator
system. #2 alternator is set to some lower-than-nominal
regulation voltage. Should the #1 alternator quit,
voltage sags and #2 wakes up. Similarly, should the
#1 alternator suffer an open winding with subsequent
loss of capacity, the voltage might sag and again,
#2 steps in to take up the slack.
In both cases, #1 alternator is running maxed out
whether by reason of total system loads =or= loss
of capacity.
If the above assumptions are accurate, how would it change if
the two alternators shared a single regulator?
(I=C3=A2=82=AC=84=A2m not advocating
this arrangement)
Cessna 336/337 Models do just that. Beech Barons too.
There is a switch for bringing a second regulator into
service should the first one fail. This philosophy
does produce a system whereby the two alternator
ammeters track each other fairly closely . . . in
my not so humble opinion, a totally misguided practice
to keep pilot's 'happy'.
There is no practical NEED for balancing the
loads on two alternators assuming (1) either
alternator can carry 100% of ships loads
with (2) demonstrated adequacy of cooling.
This shade-tree 'paralleling' scheme creates
single points of failure for both alternators.
How this got past in-house DERs is a mystery
to me . . . how the FAA bought it is a . . .
well . . . I won't go there.
Would the result change If the two alternators were PMA units,
mechanically tied together and producing a sin wave 'in-phase.'
The engines cannot be synchronized that tightly.
One final question I've wondered about. How do twin engine planes
with two alternators manage (my assumed) tendency for two alternators
in parallel quickly relying on the larger voltage out unit for most
of the current?
They parallel fields on a single regulator.
I designed a true paralleling regulator proposal for Cessna on
the 303 Crusader program thinking that there was a HUGH after market
opportunity to put the system on new and fielded Barons and
Skymasters.
I don't know how the Cessna West was wiring their airplanes.
In any case, Cessna East didn't bite on the idea so I
was never funded to pursue the design. Twin Generators on
earlier Cessna and Beech models WERE fitted with paralleling
regulators which DID NOT compromise independence of the
two system. Turbine twins have always enjoyed that design
philosophy.
Here is a sketch on a generator paralleling system
on a Beech Model 18 I think . . . but typical of
all dual generator twins of the era.
http://aeroelectric.com/Pictures/Schematics/Parallel_Aircraft_Generators.
jpg
This design uses voltage drop in the generator's
compensation windings as a current shunt. Any difference
in those two voltages biases the voltage sense windings
to depress excitation to the generator with the higher
load while elevating excitation on the lighter loaded
machine . . . pretty slick.
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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| Subject: | Re: Is there a switch configuration that will |
do this?
>However, I have not yet found one in a form factor that would match
>the rest of the standard toggles in my panel.
What switches are you using?
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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| Subject: | Re: Dual alternators |
>
>Thanks Bob, now that is amazing engineering, zero PN junctions, must
>be near bulletproof.
>Cheers,
>Brian.
Pretty close. If memory serves, some versions of
these regulators came with field remover/refurbish/
replace manuals. They're stone simple in their
physics of operation and very repairable as long
as they were not abused.
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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| Subject: | Re: Is there a switch configuration that will |
do this?
>> What switches are you using?
It appears that Stein's crew is putting these in by default unless I ask
for something else.
https://www.steinair.com/product/toggle-switch-spst-onoff-fast-on-terminals/
---
David Carter
david@carter.net
>
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| Subject: | Re: Dual alternators |
I was under the impression that the Diamond twins either had Austro
(originally Thielert) diesel engines or Lycoming avgas engines. Where
did Continental come in?
On 6/18/2021 12:48 PM, Peter Pengilly wrote:
> In Diamond twins one regulator is the master and has the job of
> balancing the alternators.
>
> Im not actually sure how it achieves that, but works well most of the time.
>
> The regulators are provided by the engine mfrs (Continental or Austro).
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| Subject: | Dual alternators |
At 02:48 PM 6/18/2021, you wrote:
>In Diamond twins one regulator is the master and
>has the job of balancing the alternators.
>
>I=99m not actually sure how it achieves that, but works well most of
the time.
Is there a .pdf of the alternator wiring you could
share? Sounds like an interesting system I'd like
to understand.
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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| Subject: | Re: Dual alternators |
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| Subject: | Re: Dual alternators |
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