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gjermundwestad(at)hotmail
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 Posted: Sat Dec 25, 2021 4:33 am Post subject: Sv: ULPower Alternator/Regulator |
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Hi!
Here is what ULPower says about their regulators capacity to handle failures. The capacitor is key....
This is from the 520T manual available on net. The 30 Amp installation might be different, but is also available online.
"The ECU needs a stable DC output . If the battery fails, or there is an open contact inside, the buffering characteristics from the battery fail also . Such a situation may result in an unstable power supply to the ECU. Therefore, we strongly recommend the installation of a genuine ULP capacitor (this capacitor is able to cover for the big amount of amps coming from the alternator/regulator) parallel on the battery.
Likewise, a failure of the RR may result in an erratic power output, which is buffered by the battery and capacitor."
Best regards
Gjermund Westad
Fra: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> på vegne av Sebastien <cluros(at)gmail.com>
Sendt: lørdag 25. desember 2021 05:23
Til: aeroelectric-l. <aeroelectric-list(at)matronics.com>
Emne: Re: ULPower Alternator/Regulator
As Dan already posted, the alternator is permanent magnet.
I was wondering more if anyone knows if the voltage regulator has any over-voltage protection included. ULPower are apparently very good about responding to inquiries so I will send them an email and post the reply to this list.
In any case, the electrical system on the aircraft in question has already been installed but was designed by a highly qualified and experienced electrical & robotics engineer with no GA aircraft knowledge. The aircraft owner sent me the diagram so that I could admire it but a quick and dirty FMEA showed some problems. A review of the manufacturer's instructions lead me to suggest that they rewire it to conform with those instructions but since the alternator wiring already includes a current limiter and a solenoid I thought it would be appropriate to leave those in rather than create the problem Joe pointed out vis a vis shorted b lead.1 If I can get permission I will post the schematic to the list; notwithstanding its problematic features it's quite a work of art.
Regards,
Sebastien
On Thu, Dec 23, 2021 at 2:11 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 11:16 AM 12/23/2021, you wrote:
| Quote: | Does anyone have experience with this system? My friend is installing a
UL350 Engine and their wiring diagram and instructions specify no protective
devices between the alternator and the battery. |
Protecting b-lead wiring from hard faults within
the alternator itself is a legacy protocol in
T/C aircraft since the first Ford alternator was
bolted to a Cessna (approx 1964).
However, LOTS of automotive applications tie
the alternator b-lead right to battery (+)
(like my '87 GMC) with some later models
adding a fusible link at the battery end
(like the 97 Chevy I worked on last week).
What kind of alternator is on the UL350, wound
field or permanent magnet?
| Quote: | Does anyone know if this alternator/regulator combination
can suffer from an overvoltage event? Or is the regulator
fault tolerant? |
There is NO alternator system immune to OV events.
Probability, severity and risk run the gamut from
a little puff of smoke to a major incendiary event.
That needs to be sorted out in a failure mode
effects analysis with appropriate prophylactics
incorporated.
As supplier of the system, the engine manufacturer
SHOULD have conducted those studies and published
well considered protocols in their manual . . .
unfortunately, few engine suppliers have any notion
of what that process entails.
The usual answer to a query on the matter is: "we've
got xxxx of these flying with no reported events of
noteworthy magnitude."
For this List to offer any more considered advice,
much more data are needed as to system characteristics.
The SAFE thing is to incorporate b-lead and ov protection
as a matter of policy . . . it's light, cheap and better
to have it and not need it as opposed to needing and
not having.
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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nuckolls.bob(at)aeroelect
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| Posted: Mon Dec 27, 2021 6:06 am Post subject: Sv: ULPower Alternator/Regulator |
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At 06:23 AM 12/25/2021, you wrote:
| Quote: | Hi!
Here is what ULPower says about their regulators capacity to handle failures. The capacitor is key....
This is from the 520T manual available on net. The 30 Amp installation might be different, but is also available online."The ECU needs a stable DC output . If the battery fails, or there is an open contact inside, the buffering characteristics from the battery fail also . Such a situation may result in an unstable power supply to the ECU. Therefore, we strongly recommend the installation of a genuine ULP capacitor (this capacitor is able to cover for the big amount of amps coming from the alternator/regulator) parallel on the battery.
Likewise, a failure of the RR may result in an erratic power output, which is buffered by the battery and capacitor." |
This narrative is nearly a clone of legacy legends about
alternator/battery operations and he real needs of automotive
electronics. Just the high points:
Batteries don't 'buffer' anything. They deliver energy at
12.5 and below, they require something on the order of
13.8 to 14.4 to charge. Between those conditions,
they're very nearly an open circuit. They cannot
act as some sort of super-capacitor that smooths the
alternator's output voltage.
Put an oscilloscope on the DC bus while your
car is operating under various electrical
system demands . . . VERY trashy whether the battery
is connected or not.
A battery IS a storage vessel for energy when the
alternator quits . . . it WILL stand off the over-
excited alternator run-away and/or alternator-
load dump for the hundreds of milliseconds that
the OV management system needs to make up its mind.
But in no way is it any kind of filter for normal
operations of the ship's electro-whizzies.
Check out the suite of plots taken from a B&C
SD-8 alternator under various conditions of
load, and existence of battery and/or 'filter'
capacitor.
https://tinyurl.com/y6tgyzaa
Note that under light loads is when ripple is
greatest. The presence of a battery or capacitor
makes little observable difference . . . cause
under load, the alternator's ripple voltage
is rather small.
"Unstable power supply" is not defined. What's nominal?
What are acceptable excursions from nominal that
degrade ECU performance?
What size capacitor? You can easily calculate capacitor size
needed to reduce a KNOWN ripple voltage under KNOWN current
demands to an ACCEPTABLE amplitude per requirements
stated above. (Hint . . . it's a LOT bigger than
the 'recommended' sizes published by most manufacturers)
Since requirements for the ECU and alternator
output characteristics are not stated the value
of or justification for a capacitor is not
validated.
If OBAM aviation has a significant downside, it's
that many products are sold and operated on aircraft
with meager knowledge of the performace NUMBERS. We're
the world's largest consumers of field-qualified
products in aviation.
If I were tasked to integrate this engine and its
supplied accessories into a TC aircraft, ALL those
numbers would be KNOWN by qualification and flight
tests documented in voluminous reports. Both
alternator/battery system AND ECU would be qualified
to some normal and adverse conditions and NUMBERS
secured to assure a harmonious marriage with the
ship's compliment of electrics.
The statement quoted is pretty 'generic' . . .
offered up by most engine suppliers to OBAM aviation
for decades but not backed up with documented,
quantified physics.
If ANY supplier to the OBAM aviation market finds
these assertions in error, please, Please, PLEASE
join us here and make your argument. The last
thing we wish to do here is be an echo chamber
for bad information.
Make my day . . . show me where I'm wrong!
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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