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https://www.rotax-owner.com/en/912is-technical-questions/8513-overheating-voltage-regulator-b

 

I read there that unlike the ULS, the iS voltage regulators shunt all unused current to ground and waste generator power so the generators are always running at maximum capacity. Can I replace the regulators on the iS with an aftermarket non-shunting model like Silent Hektik? I've been looking online for more than an hour and all information I see is about replacing the regulator for the ULS.

  • Re: Aftermarket voltage regulators for 912iS?

    by » one week ago


    Hi Joe

    The electrical system is a completely different design from the ULS.  The ULS is a single phase 250W generator.  The iS is a three phase split system, 400W for the aircraft and 200W for the critical operational bits.  (2 wire AC in for the ULS and 3 wire on the iS were each is one leg of the 3 phase)  Given this the shunt regulators used on the iS is used and dumps unused energy to ground.  I am not aware of any replacements for that design.  The Silent Hektik for the ULS will not work.  

    Cheers


  • Re: Aftermarket voltage regulators for 912iS?

    by » one week ago


    Rotax Wizard wrote:

    Hi Joe

    The electrical system is a completely different design from the ULS.  The ULS is a single phase 250W generator.  The iS is a three phase split system, 400W for the aircraft and 200W for the critical operational bits.  (2 wire AC in for the ULS and 3 wire on the iS were each is one leg of the 3 phase)  Given this the shunt regulators used on the iS is used and dumps unused energy to ground.  I am not aware of any replacements for that design.  The Silent Hektik for the ULS will not work.  

    Cheers

    So the iS has two (three phase) generators of 400W and 200W and two regulator rectifiers one for each. What is preventing an aftermarket regulator from working then? Would I need to find a regulator which has three phase input with sufficient wattage capacity? Some motorcycles have three phase rectifiers.


  • Re: Aftermarket voltage regulators for 912iS?

    by » one week ago


    Is a unit like https://www.aircraftspruce.com/catalog/elpages/kuntzillus.php compatible with the 912iS? This is a strobe that claims to use all unused power from the regulator. I figure that is more efficient (less chance of current overdraw) than using a high power strobe that's almost 400W total in order to nearly max out the B regulator.


  • Re: Aftermarket voltage regulators for 912iS?

    by » one week ago


    On the iS series of engines it has 1 (one) stator.  This is a 600 watt generator where the sator is split into 400 watt for the B regulator  and 200 watt for the A regulator.  They are 3 phase.  Yes if you wish to search out a motorcycle unit and test it that might work however you're going to have to do the verification as to suitability.  I am unaware personally of anyone who has tested this.  

     

    Cheers 


  • Re: Aftermarket voltage regulators for 912iS?

    by » 3 days ago


    I know it's one stator and the ULS is pretty much the same, but single phase (and with two coils for mags, a few more for the generator, and one to count revs). I guess they did that so it would be electrically isolated even if it was not physically isolated.

     

    Are both regulator rectifiers for A and B identical? Is there anything special about them, or would any full-wave rectifier and a switching regulator work the same, assuming that it was designed for an engine environment, the voltage (and current capacity) was correct and there wasn't too much AC ripple?


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