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Regulator/Rectifier

  • Rotaxrobert
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2 years 3 weeks ago #14717 by Rotaxrobert
Regulator/Rectifier was created by Rotaxrobert
On a recent cross-country flight in an RV-12 ( Skyview installation), the voltmeter started spiking between 14.4 volts and 15.8 volts. I Landed as soon as possible. Lockwood Aviation tech support thought it was either the regulator/rectifier or perhaps the R, B+ or C wire. I was carrying an extra regulator/rectifier due to their notorious reputation. When I inspected the old regulator and the connectors, there were no signs of overheating. Nevertheless, I replaced it with the new one. It appeared to work on the ground. When I took off again, it worked for about 1 hour and then started spiking again.

From other things I have read, I suspect that the C wire is not seating properly and when I connected the new regulator, it seated temporarily but become loose again in flight.

I would appreciate any comments on this. We have not been able to get back out to the aircraft to check this connector.

Also, I am trying to figure out exactly what the C connector does. The other four I was able to trace on the schematic, however, the C wire appears to get connected to the Skyview, but I cannot tell what its function is.

Thanks for any comments.

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2 years 3 weeks ago #14720 by jacques44
Replied by jacques44 on topic Regulator/Rectifier
I had the same problem, I have then removed the original connector, replaced it with individual inox lug connectors with heat shrink and since, no problem.

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2 years 3 weeks ago - 2 years 3 weeks ago #14728 by MMiller
Replied by MMiller on topic Regulator/Rectifier
The regulator C pin is the control input. It senses system voltage (battery voltage, plus regulator output, minus system load) to turn the regulator on and off. If the voltage to this pin is above three volts there is enough power to turn ON the regulator, once the pin voltage exceeds 14 volts the output is turned OFF.

On the RV12, the C pin is connected to the main BUS through the second pole of the master switch.

The typical failure mode for a Rotax regulator is reduced output, or no output, so your regulator is likely good. A resistive connection in the C pin circuit will give you an overvoltage condition because the regulator is trying to compensate for the voltage drop seen on the sense pin.

As a side note, the Amp Faston connector is rated for 10 mating cycles....a "knock-off" part may be of lesser quality.
Last edit: 2 years 3 weeks ago by MMiller.

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2 years 3 weeks ago #14763 by Rotaxrobert
Replied by Rotaxrobert on topic Regulator/Rectifier
Thank you for your response. I have never heard of a inox lug connector.

Do you have a source for that? I would like to see what one looks like and how it compares to the connector I am currently using.

It turned out that the C connector was not seated properly in the connector housing and it appears to be working correctly now but I am interested in better solutions.

Thank you

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2 years 3 weeks ago #14764 by Rotaxrobert
Replied by Rotaxrobert on topic Regulator/Rectifier
Mike,
Thank you for the excellent explanation.
It turned out that the C pin was not seated properly in the connector housing. We re-inserted it and after almost two hours of flying, everything appears to be OK.
I am still confused and concerned on one point-
Did we really have a overvoltage condition or did our voltmeter just indicate an overvoltage condition?
The reason I am trying to clarify this is that I am concerned that I might have damaged the battery or electrical system.
When I was trying to figure this out, I contacted Odyssey battery to get their perspective. They felt that if I had a real overvoltage situation, then the battery would have failed. They said the battery has a built in venting system so it will not explode, however, we would have smelled an odor like rotten eggs. I inspected the battery. It appeared normal plus there was no odor. Furthermore, after we fixed the problem, it had no problem starting the aircraft. Maybe the battery can handle more volts than they recommend (15 volts max.)

Do you have any thoughts on this?

You have been a tremendous help.

Thank you.

Bob

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2 years 3 weeks ago #14766 by MMiller
Replied by MMiller on topic Regulator/Rectifier
Bob,
Your welcome.

With a resistive connection on the C pin you did have an over-voltage condition. The displayed voltages and alarms were accurate. But I wouldn't worry about it, I doubt anything was damaged. Most of your expensive avionics devices are designed for 12 - 28 volt operation, so no problem here. I agree with the people at Odyssey, the battery is robust, its not going to catch fire or melt down, worst case is you may have shortened its life, but I doubt it. The only thing I can think of that may have caused the smell are the two cooling fans under the panel. These fans use stepping motors and are rated for 12 volts, they may not tolerate an over voltage, just a guess here. But easy to check, turn the master on and see if they spin. Good luck.

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2 years 3 weeks ago #14767 by jacques44
Replied by jacques44 on topic Regulator/Rectifier

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2 years 3 weeks ago - 2 years 3 weeks ago #14772 by Bill Hertzel
Replied by Bill Hertzel on topic Regulator/Rectifier
INOX, from the French, Inoxydable (Non-Oxidizable)

Commonly referred to in the U.S. as Stainless Steel.
Last edit: 2 years 3 weeks ago by Bill Hertzel.

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2 years 3 weeks ago #14773 by jacques44
Replied by jacques44 on topic Regulator/Rectifier
In fact, the lugs of my connectors were oxidized .

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2 years 2 weeks ago #14774 by Roger Lee
Replied by Roger Lee on topic Regulator/Rectifier
If you have corrosion issues from living in a moist humid climate you can use some dielectric grease on your contacts to help prevent the oxidation.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
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2 years 2 weeks ago #14775 by Rotaxrobert
Replied by Rotaxrobert on topic Regulator/Rectifier
Actually, there was no odor. Odyssey said that was a sign to look for. So I guess we are OK and I will keep an eye on the battery.

You are very knowledgeable and I appreciated the time you took to reply to my question.

Bob

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2 years 2 weeks ago #14776 by Rotaxrobert
Replied by Rotaxrobert on topic Regulator/Rectifier
No
I had never heard of it, but now I know and I really appreciate the time you took to help with my question.

Bob

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2 years 2 weeks ago #14777 by jacques44
Replied by jacques44 on topic Regulator/Rectifier
Indeed, I live near the Atlantic Ocean, and corrosion is a problem
Thank you Roger for your advice

Jacques

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2 years 5 days ago #14834 by Ukpylot
Replied by Ukpylot on topic Regulator/Rectifier
I've just started to look at the electrical system install for the Rotax 912 ULS I am attempting to put in the Zenith CH750 I'm attempting to build and wondered if anyone could explain to me the purpose of the individual C, R and B wires. It looks like the three get combined (with the capacitor) and go as one wire to the.... ? I can't work out if it goes to the battery or the 'alternator input' on my power panel.

I'm totally new to all of this plane building thing but I firgure I'll only learn by asking questions so any advice/help appreciated. It would be great to get a first engine start over the new year, but I want to make sure i get it right.

Paul

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2 years 5 days ago #14837 by MMiller
Replied by MMiller on topic Regulator/Rectifier
Do not tie the three pins together and come out with one wire.

The R and +B pins are the regulator output and are internally jumped, so these two wires can be tied together. This typically feeds your bus through a fuse, about 30A.

The C pin is control and sense. Power to the C pin turns ON the regulator, when the C pin senses greater than 14 volts, it turns OFF the output to R and +B. If you jump the C pin to the R and +B pin, the regulator will self excite and can only be turned off by stopping the engine because the R and +B will feed the C pin until the magnets stop spinning. Opening the master switch will only disconnect your battery and cause wide voltage swings on the bus.

I would use a two pole master switch, one pole to power the master relay, the second pole connects the C pin to your bus.

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2 years 2 days ago #14848 by Ukpylot
Replied by Ukpylot on topic Regulator/Rectifier
Hmm thanks for the reply and explanation - that helps a lot with my understanding of how this works. Most all of the examples I see online use the three wire method but I can see that this would be better.

Cheers.

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2 years 1 day ago #14860 by jiott
Replied by jiott on topic Regulator/Rectifier
I would seriously question the advice of Mr. Miller because the Rotax 912 installation manual section 24-00-00 page 19 clearly shows all 3 R, B+, and C terminals tied together before going into the fuse/breaker. Why would the factory recommend this and thousands of us have followed it if it was so bad?

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4 months 4 days ago - 3 months 1 week ago #19970 by AdoraKalb
Replied by AdoraKalb on topic Regulator/Rectifier
Hi...i am a new user here. As per my knowledge If the voltage to this pin is above three volts there is enough power to turn ON the regulator, once the pin voltage exceeds 14 volts the output is turned OFF.On the RV12, the C pin is connected to the main BUS through the second pole of the master switch.
The typical failure mode for a Rotax regulator is reduced output, or no output, so your regulator is likely good.

percent calculator
Last edit: 3 months 1 week ago by AdoraKalb.

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4 months 2 days ago #19981 by MMiller
Replied by MMiller on topic Regulator/Rectifier

jiott wrote: I would seriously question the advice of Mr. Miller because the Rotax 912 installation manual section 24-00-00 page 19 clearly shows all 3 R, B+, and C terminals tied together before going into the fuse/breaker. Why would the factory recommend this and thousands of us have followed it if it was so bad?


Mr. Ott, I’m sorry for the late reply, I missed your comment. Can you find any fault(s) in my statements above? or below? Because Rotax says so is a poor argument in light of the facts. You can wire your aircraft anyway you like, but you should be aware of the consequences. I welcome your peer review.

The Ducati regulator wired according to Rotax’s suggested/mandated wiring will put that aircraft out of compliance with the LSA consensus standards.

To recap, if you wire your aircraft according to Rotax, once the engine is running, the power provided from the alternator will self-excite the regulator. The system will continue to produce power even after the battery has been disconnected. The bus will remain powered, until the engine stops turning. you do NOT have a master switch, you have a “alternator trigger“/“battery disconnect” switch.

Look closely at the disclaimers in the Rotax documentation. Rotax will argue that they make engines and it’s up to the aircraft manufacturer/builder to comply with the regulations.

Please review the following reference documents.

LSA Consensus Standards, From ASTM 2245

8 ) required equipment
8.4.1 ) If installed, an electrical system shall include a master switch and overload protection devices (fuses or circuit breakers.)

The function of a master switch from part 23 (yes I know we are not part 23, but this is the definition the FAA/NTSB will use as a default in the accident report after the inflight fire of an electrical system on a 912ULS that could not of be shutdown.)

§ 23.1361 Master switch arrangement.
(a) There must be a master switch arrangement to allow ready disconnection of each electric power source from power distribution systems, except as provided in paragraph (b) of this section. The point of disconnection must be adjacent to the sources controlled by the switch arrangement. If separate switches are incorporated into the master switch arrangement, a means must be provided for the switch arrangement to be operated by one hand with a single movement.
(b) Load circuits may be connected so that they remain energized when the master switch is open, if the circuits are isolated, or physically shielded, to prevent their igniting flammable fluids or vapors that might be liberated by the leakage or rupture of any flammable fluid system; and
(1) The circuits are required for continued operation of the engine; or
(2) The circuits are protected by circuit protective devices with a rating of five amperes or less adjacent to the electric power source.
(3) In addition, two or more circuits installed in accordance with the requirements of paragraph (b)(2) of this section must not be used to supply a load of more than five amperes.
(c) The master switch or its controls must be so installed that the switch is easily discernible and accessible to a crewmember.

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4 months 2 days ago #19982 by jiott
Replied by jiott on topic Regulator/Rectifier
I am certainly not an electrical guru and would never claim to be, so I don't have the qualifications to either verify or dispute what Mr. Miller has said. However, I am smart enough to NEVER trust one opinion from someone I do not know, especially on the "internet". Also I am more inclined to trust the instructions from the engine manufacturer, based on thousands of successful installations. What I would really like to see is a response from Rotax administration regarding Mr. Miller's comment; also from other knowledgeable persons.

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