Another Ducati Regulator Question

by Ken Ryan in 912 / 914 Technical Questions 6 years ago

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Re: Another Ducati Regulator Question

by Ken Ryan » 6 years ago

Ken Ryan

28 360 928

Thank you!

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Re: Another Ducati Regulator Question

by RotaxOwner Admin » 6 years ago

RotaxOwner Admin

59 1.58k 13.9k

OK, here is the story:

First off, there is NO specific method approved or supplied by ROTAX to instruct you on how to accomplish the cooling of the regulator.

All that is 'writ in stone' is that your installation should ensure that the rectifier-regulator does not exceed the specified temperature limits.

The task of determining the correct and safe way to ensure proper cooling is left to the discretion (and responsibility) of the airframe manufacturer. If location alone does not solve an overheating situation, then it's left open for "the airframer" to find another solution - possibly a heat sink. (The "NOTE" is just that, a note suggesting that you are allowed to try a heatsink if you think it could provide a solution for you.)

Personally I can imagine a couple of different ways to professionally mount this component "with an additional heat sink", but in the final analysis, such an application is going to be very dependent on the exact details of your own particular installation...

Thank you said by: Ken Ryan

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Re: Another Ducati Regulator Question

by Rotax Wizard » 6 years ago

Rotax Wizard

1 707 3.13k

When we look at this type of regulator it should be noted that they are a shunt type. That means they require a load to run them in the cooler modes. If your aircraft has a very small electrical load then the excess electrical energy will shunt to ground at the regulator ground, In the case of the Ducati this is the mounting bolts to whatever location you have it placed. The ground has to reach back to the engine to complete the circuit. I always suggest a separate ground wire from the mount lug to the engine itself to ensure that it can complete the loop without any issue. The electrical parts inside are sensitive to heat and the Rotax recommendation is to mount it where it can stay below 80C (176F) so as to protect the internal parts. Be sure that the engine has a constant electrical load by mounting the requested capacitor as shown in the installation manual.

happy trails

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Re: Another Ducati Regulator Question

by Mike Miller » 6 years ago

Mike Miller

0 41 99

Wizard,
I don’t know about the two cycle Rotax engines, but the Ducati on the 912 series is NOT a shunt regulator. It is simply a full wave bridge that turns OFF once the “C” pin senses ~14 volts. The heat generated at the regulator is proportional to the output current. At low output power, negligible heat is produced. At zero output, no heat is generated.
I’m confused by your claim that the charging system needs an additional ground wire to the engine. The stator charging coils are isolated from any ground reference. Once running, the only current in the engine ground wire is from the three temperature sensors.

Yes, I agree that heat is the enemy of electronics, but these regulators don’t die from electronics failures. I have examined dozens of failures and ALL the failures are mechanical.

Eric, if you want to put this problem behind you, or you need convincing you have a problem, I would be happy to discuss this with you... but a forum is not the place.

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Another Ducati Regulator Question

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