Today's Message Index:
----------------------
1. 06:20 AM - Re: Sequence for bringing alternators on line. (Robert L. Nuckolls, III)
2. 06:23 AM - Re: Re: Sequence for bringing alternators on line. (Robert L. Nuckolls, III)
3. 08:16 AM - STARTER VOLTAGE SPIKE (user9253)
4. 08:17 AM - Re: Sequence for bringing alternators on line. (Carlos Trigo)
5. 08:30 AM - Re: Sequence for bringing alternators on line. (William Hunter)
6. 08:55 AM - Re: Sequence for bringing alternators on line. (Robert L. Nuckolls, III)
7. 09:01 AM - Re: Sequence for bringing alternators on line. (Robert L. Nuckolls, III)
8. 09:05 AM - Re: STARTER VOLTAGE SPIKE (Charlie England)
9. 09:13 AM - Re: STARTER VOLTAGE SPIKE (Robert L. Nuckolls, III)
10. 12:23 PM - Re: Sequence for bringing alternators on line. (William Hunter)
11. 01:16 PM - Re: Re: Sequence for bringing alternators on line. (Sebastien)
12. 01:31 PM - Re: Alternator Noise When Touching Metal Airframe Grounds (Jared Yates)
13. 01:41 PM - Re: Re: Rotax Charging System (Sebastien)
14. 02:55 PM - Re: Rotax Charging System (user9253)
15. 04:32 PM - Re: Alternator Noise When Touching Metal Airframe Grounds (Robert L. Nuckolls, III)
16. 07:39 PM - Re: Re: Rotax Charging System (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Sequence for bringing alternators on line. |
At 05:46 PM 6/12/2018, you wrote:
>I am writing checklists for a new homebuilt I will be doing the
>flight testing on. Aircraft has a 40A main alternator and an SD-8
>backup alternator. The alternator switch allows either the main or
>backup alternator to be on and also has an off position. I'm
>thinking of leaving the switch on the main alternator all the time,
>except for a test of the SD-8 during the runup. Does anyone see a
>problem with this plan or should I wait until the load on the
>electrical system has come down to a certain point before switching
>to the SD-8? As far as I know the SD-8 will put out whatever it can
>and any load in excess will simply come from the battery.
Sequencing optoins are not critical. The alternator(s)
may be off or on before starting . . . and order of
shutdown at stopping is similarly unimportant.
Emacs!
>Is it reasonable to test the SD-8 every flight or is this something
>that can be done on a monthly or quarterly basis? Also I have run
>into a couple pilots recently who start their engines with the
>alternator off in order to "prevent damage to the alternator during
>start". I can't remember any mention of this in the AEC. Is there
>any basis for this? Should I turn the alternator off before shutdown
>and then on after startup?
The SD8 is very reliable . . . especially
when held in reserve, It's output at
run-up rpm will be rather limited. If you
run up at 1800 rpm, the SD8 will be turning
~2340 and produce about 4A of output.
Depending on the type and condition of
battery . . . and system loads . . .
you'll need to look closely at
bus voltage to make sure it changes
upward by any observable amount
when turned ON.
Testing ever so often while in-flight
would be easier to do . . . you can also
use the flight test to verify your plan-b
loads such that the battery is not discharged
during the en route phase of flight and
held in reserve for descent, approach
and landing.
The risk of damaging an alternator
or other electrowhizzies by the mismanagemet
of alternator switches during normal operations
is a myth. You may sequence their switching
in any manner that makes sense to you.
Bob . . .
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Subject: | Re: Sequence for bringing alternators on line. |
At 09:07 PM 6/12/2018, you wrote:
>
>The two relays and starter contactor should all have diodes just
>like the battery contactor does. Connect banded end of diodes to positive.
> Can the start switch handle the start contactor coil current? Or
> is the E-123 Relay necessary?
The ACS/Bendix/Gerdes key switch will handle
the automotive starter contacter that's fitted
with a supression diode. Many (like the B&C
S702) have the diode built in. If in doubt,
install a second one . . . two are better
than none. The buffer relay is not necessary
but doesn't hurt anything . . . if left in
add the diode to it too as Joe suggests.
Bob . . .
Message 3
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Subject: | STARTER VOLTAGE SPIKE |
Below is a quote from VansAirforce post #24 by Cumulo
http://www.vansairforce.com/community/showthread.php?t=160519
>
> Re:big bang
> The diode bridge inside the average alternator is robust enough to snub and dissipate
the starter energy provided the alternator "A" lead is intact and on
line across the bus.
> From my perspective Nuckolls is a new guy. He didn't start monkeying with this
stuff 'till Cessna had begun using alternators, so he is not well placed to
be the last word on this subject.
>
> Let me describe the sequence involving a starter that has the potential to damage
electronic stuff:
> 1. The Master is turned on, connecting the battery to the bus.
> 2. The starter button is pushed, energizing the starter solenoid
> 3. The starter solenoid connects the starter to the bus.
> 4. several hundred amps flow to the starter and the starter begins to spin the
engine.
> 5. Battery is low, so starter slows and and stalls.
> 6. the stalled starter with a hundreds of amps demand pulls the bus voltage down
to a few volts.
> 7. Master solenoid drops out , disconnecting battery from bus.
> 8. the very strong magnetic field of the starter collapses (the starer now is
just a massive inductor of copper and iron)
> 9. A very high energy spike WILL BE produced if there is nothing to snub and
dissipate it.
>
> The above is not the normal start sequence. Normally, the STARTER solenoid releases
first,turning the starter off and the starter energy is dissipated on the
solenoid copper contacts.
>
> BTW, proof by authority is not a good way to argue, but I DO have an A&P, accessories,
radio, instrument repairman certs, had a repair station for a decade
and stick wise most everything but an ATP. And way back when I worked for a living
I was an Electrical Engineer doing mostly military and computer design stuff.
>
> Nuckolls has done some really good stuff and I tip my hat to him, but I can demo
blowing a small diode out with a starter spike any old time.
>
> I think that having to start a dark airplane is too restrictive, too old timey.
Protection should be standard so strobes, radios, EFIS, EMS audio amps can
be on with no fear of damage from any cause. Stay tuned.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480847#480847
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Subject: | Re: Sequence for bringing alternators on line. |
Bob
Are your assertions below, about the SD-8, also valid for the SD-20 (now BC-
410H)?
Thanks
Carlos
Enviado do meu iPhone
No dia 13/06/2018, =C3-s 14:19, Robert L. Nuckolls, III <nuckolls.bob@aero
electric.com>
> The SD8 is very reliable . . . especially
> when held in reserve, It's output at
> run-up rpm will be rather limited. If you
> run up at 1800 rpm, the SD8 will be turning
> ~2340 and produce about 4A of output.
>
> Depending on the type and condition of
> battery . . . and system loads . . .
> you'll need to look closely at
> bus voltage to make sure it changes
> upward by any observable amount
> when turned ON.
>
> Testing ever so often while in-flight
> would be easier to do . . . you can also
> use the flight test to verify your plan-b
> loads such that the battery is not discharged
> during the en route phase of flight and
> held in reserve for descent, approach
> and landing.
>
> The risk of damaging an alternator
> or other electrowhizzies by the mismanagemet
> of alternator switches during normal operations
> is a myth. You may sequence their switching
> in any manner that makes sense to you.
>
>
> Bob . . .
Message 5
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Subject: | Re: Sequence for bringing alternators on line. |
Regarding the SD 20, does anybody know what its output should at 1,000 RPM
(engine idle) and also at 2400 RPM Cruise?
Thanks,
Bill Hunter
On Wed, Jun 13, 2018, 11:23 Carlos Trigo <trigo@mail.telepac.pt> wrote:
> Bob
>
> Are your assertions below, about the SD-8, also valid for the SD-20 (now
> BC-410H)?
>
> Thanks
> Carlos
>
> Enviado do meu iPhone
>
> No dia 13/06/2018, =C3-s 14:19, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com>
>
> The SD8 is very reliable . . . especially
> when held in reserve, It's output at
> run-up rpm will be rather limited. If you
> run up at 1800 rpm, the SD8 will be turning
> ~2340 and produce about 4A of output.
>
> Depending on the type and condition of
> battery . . . and system loads . . .
> you'll need to look closely at
> bus voltage to make sure it changes
> upward by any observable amount
> when turned ON.
>
> Testing ever so often while in-flight
> would be easier to do . . . you can also
> use the flight test to verify your plan-b
> loads such that the battery is not discharged
> during the en route phase of flight and
> held in reserve for descent, approach
> and landing.
>
> The risk of damaging an alternator
> or other electrowhizzies by the mismanagemet
> of alternator switches during normal operations
> is a myth. You may sequence their switching
> in any manner that makes sense to you.
>
>
> Bob . . .
>
>
Message 6
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Subject: | Re: Sequence for bringing alternators on line. |
At 10:09 AM 6/13/2018, you wrote:
>Bob
>
>Are your assertions below, about the SD-8, also valid for the SD-20
>(now BC-410H)?
>
>Thanks
>Carlos
Any alternator . . .
I've been working with engine driven power sources on
aircraft and ground based vehicles for a long time. I've
spent hours in the lab with various alternators and generators
on test stands exploring system performance of the
various components with some pretty illuminating
test equipment.
Not once have I observed any adverse behaviors of
these machines when turning on or off EXCEPT for
the classic, uniquely AUTOMOTIVE definition of a
LOAD DUMP. This is a carefully orchestrated
condition where the system loads are low to zero.
The alternator is working hard to RECHARGE a
DEPLETED battery. The BATTERY becomes disconnected
from the bus.
This is the electronic equivalent of playing tug-of-war
wherein both sides have their heels dug in and are
straining on the rope . . . then you cut the rope
. . . EVERYBODY hits the ground.
I could duplicate this condition in a Bonanza or
Baron where the alternator(s) and battery are
on separate switches. Discharge the battery,
crank with ground power, turn on the alternator(s)
and then turn the battery off. Sho' 'nuf . . . you're
going to get a big bump in alternator output
due to a predictable delay in voltage regulator response
to a sudden drop in load wherein the BATTERY's
mitigating influence on such events is not present.
Now, how often and under what circumstances would
such an event happen in YOUR airplane?
Bob . . .
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Subject: | Re: Sequence for bringing alternators on line. |
At 10:29 AM 6/13/2018, you wrote:
>Regarding the SD 20, does anybody know what its output should at
>1,000 RPM (engine idle) and also at 2400 RPM Cruise?
>
>Thanks,
See https://goo.gl/m6i8qR
At engine 1000 rpm, alternator rpm is about 1300 . . .
you might see 5 or so amps.
At engine 2400, alternator 3,000 the chart
says 29A
Bob . . .
Message 8
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Subject: | Re: STARTER VOLTAGE SPIKE |
On 6/13/2018 10:15 AM, user9253 wrote:
>
> Below is a quote from VansAirforce post #24 by Cumulo
> http://www.vansairforce.com/community/showthread.php?t=160519
>
>> Re:big bang
>> The diode bridge inside the average alternator is robust enough to snub and
dissipate the starter energy provided the alternator "A" lead is intact and on
line across the bus.
>> From my perspective Nuckolls is a new guy. He didn't start monkeying with this
stuff 'till Cessna had begun using alternators, so he is not well placed to
be the last word on this subject.
>>
>> Let me describe the sequence involving a starter that has the potential to damage
electronic stuff:
>> 1. The Master is turned on, connecting the battery to the bus.
>> 2. The starter button is pushed, energizing the starter solenoid
>> 3. The starter solenoid connects the starter to the bus.
>> 4. several hundred amps flow to the starter and the starter begins to spin the
engine.
>> 5. Battery is low, so starter slows and and stalls.
>> 6. the stalled starter with a hundreds of amps demand pulls the bus voltage
down to a few volts.
>> 7. Master solenoid drops out , disconnecting battery from bus.
>> 8. the very strong magnetic field of the starter collapses (the starer now is
just a massive inductor of copper and iron)
>> 9. A very high energy spike WILL BE produced if there is nothing to snub and
dissipate it.
>>
>> The above is not the normal start sequence. Normally, the STARTER solenoid releases
first,turning the starter off and the starter energy is dissipated on
the solenoid copper contacts.
>>
>> BTW, proof by authority is not a good way to argue, but I DO have an A&P, accessories,
radio, instrument repairman certs, had a repair station for a decade
and stick wise most everything but an ATP. And way back when I worked for a
living I was an Electrical Engineer doing mostly military and computer design
stuff.
>>
>> Nuckolls has done some really good stuff and I tip my hat to him, but I can
demo blowing a small diode out with a starter spike any old time.
>>
>> I think that having to start a dark airplane is too restrictive, too old timey.
Protection should be standard so strobes, radios, EFIS, EMS audio amps can
be on with no fear of damage from any cause. Stay tuned.
>
> --------
> Joe Gores
>
Yeah, I replied to it, as well. Hilarious.
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Message 9
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Subject: | Re: STARTER VOLTAGE SPIKE |
At 10:15 AM 6/13/2018, you wrote:
>
>Below is a quote from VansAirforce post #24 by Cumulo
>http://www.vansairforce.com/community/showthread.php?t=160519
This is a myth that has been propagated for
decades and has no foundation in physics.
Recall that the bench demonstrations for dissipating
the magnetic field collapse in a battery contactor
showed that the energy resulting from the spike
was dissipated in an arc that forms between the
spreading contacts of the controlling device, i.e.
the switch. The energy did NOT propagate onto the
bus in any significant way.
The same thing happens with starters except the
device taking the abuse is the starter contactor.
Yeah, there's some fire between the opening
contacts but that energy has to jump the RESISTANCE
of the arc and then boost the bus voltage against
the surge mitigating effects of battery(s) and
a host of capacitors built into the electrowhizzies.
Not once in 50 years of pondering the vagaries of
electrical system gremlins on vehicles have I
seen a measured/demonstrated risk to electrowhizzies
from a release energy stored on the starter's
inductance.
WAaayyy back when, we thought that 'starter
spikes' were killing the transistors in the newly
minted solid state features of radios at Cessna.
It turned out that depressed bus voltage during
cranking due to soggy battery was killing the
radios . . . NOT starter spikes.
That REAL threat to EARLY solid state designs
has been fertilized into any number of ol' pilot's
tales that are without foundation.
Bob . . .
Message 10
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Subject: | Sequence for bringing alternators on line. |
Thanks!!!
Bill Hunter
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, June 13, 2018 9:01 AM
Subject: Re: AeroElectric-List: Sequence for bringing alternators on line.
At 10:29 AM 6/13/2018, you wrote:
Regarding the SD 20, does anybody know what its output should at 1,000 RPM
(engine idle) and also at 2400 RPM Cruise?
Thanks,
See https://goo.gl/m6i8qR
At engine 1000 rpm, alternator rpm is about 1300 . . .
you might see 5 or so amps.
At engine 2400, alternator 3,000 the chart
says 29A
Bob . . .
Message 11
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Subject: | Re: Sequence for bringing alternators on line. |
The starter contactor is a B&C S702 and SD-8 relay is included in the PMOV
kit so I think the diode is built in as well.
The E-123 relay is not necessary in the current setup but this system was
originally designed for P-Mags and the start switch was going to be an
S2000 button. I'm guessing that the S2000 needed the relay and when it was
replaced with an ACS switch the relay was left in for later conversion.
Thank you all for the replies, I'll just leave the alternator switch on
Main all the time since there's no advantage to turning it off for engine
start. Once the aircraft is through its test phase we plan on testing the
SD-8 on an every 4 months schedule.
On Wed, Jun 13, 2018 at 6:22 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 09:07 PM 6/12/2018, you wrote:
>
>
> The two relays and starter contactor should all have diodes just like the
> battery contactor does. Connect banded end of diodes to positive.
> Can the start switch handle the start contactor coil current? Or is the
> E-123 Relay necessary?
>
>
> The ACS/Bendix/Gerdes key switch will handle
> the automotive starter contacter that's fitted
> with a supression diode. Many (like the B&C
> S702) have the diode built in. If in doubt,
> install a second one . . . two are better
> than none. The buffer relay is not necessary
> but doesn't hurt anything . . . if left in
> add the diode to it too as Joe suggests.
>
>
> Bob . . .
>
Message 12
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Subject: | Re: Alternator Noise When Touching Metal Airframe Grounds |
Thanks Bob, I'll try that early next week and report back. What I was
calling alternator noise does rise and fall with engine RPM, and goes away
when I pull the main alternator field CB.
On Tue, Jun 12, 2018 at 6:13 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 03:01 PM 6/12/2018, you wrote:
>
> Yes, and also a gns430w and skyview system.
>
>
> Just for grins . . . try unplugging the
> data cable between the intercom/controll
> panel and the remote transceiver . . . and
> see if the noise is affected.
>
> Oh yeah, are you sure it's alternator whine . . .
> pitch rises and falls with engine rpm?
>
>
> Bob . . .
>
Message 13
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Subject: | Re: Rotax Charging System |
Joe the Ducati has 6 pins instead of 5 for the John Deere. I believe the
extra pin on the Ducati is for a large capacitor but the John Deere ones
are MOSFET rectifiers which don't need the capacitor? So we could hook up
the two AC wires, the B+, the L, and the IGN wires the same as on the
Ducati and just remove the cap from the system? Am I making any sense?
On Mon, Jun 11, 2018 at 11:15 AM, user9253 <fransew@gmail.com> wrote:
>
> Search eBay for AM101406 or MIA881279
> Chances are that the $20 ones are the same as the more expensive ones.
> Note that the terminals are arraigned in a different order than the
> Ducati. The mounting holes are also spaced differently. Be sure to use
> heat conductive grease on the mounting base to carry heat away.
>
> > Any luck on a part number or a way to determine an appropriate John
> Deere regulator?
>
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480794#480794
>
>
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Subject: | Re: Rotax Charging System |
Neither the Ducati or John Deere regulator has a terminal specifically for a capacitor,
although some installers might connect a capacitor to Ducati terminal
R. Terminals B and R are connected together internally. I believe the purpose
of the R terminal is not for redundancy, but rather to reduce current through
a single terminal. A capacitor is required regardless of which regulator is
used. It can be connected to the main power bus. I put a 10 amp fuse in series
with mine.
Splice the two wires together that were connected to Ducati terminals B & R and
connect to John Deere terminal B+.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480867#480867
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Subject: | Re: Alternator Noise When Touching Metal Airframe |
Grounds
At 03:31 PM 6/13/2018, you wrote:
>Thanks Bob, I'll try that early next week and report back. What I
>was calling alternator noise does rise and fall with engine RPM, and
>goes away when I pull the main alternator field CB
very well . . . just making sure we're
peering into the right rabbit hole . . .
Bob . . .
Message 16
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Subject: | Re: Rotax Charging System |
At 03:41 PM 6/13/2018, you wrote:
>Joe the Ducati has 6 pins instead of 5 for the
>John Deere. I believe the extra pin on the
>Ducati is for a large capacitor but the John
>Deere ones are MOSFET rectifiers which don't
>need the capacitor? So we could hook up the two
>AC wires, the B+, the L, and the IGN wires the
>same as on the Ducati and just remove the cap
>from the system?=C2 Am I making any sense?
As long as you have a battery on line,
the capacitor serves no demonstrable
purpose.
Bob . . .
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