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peterz(at)zutrasoft.com
Guest

Posted: Tue Jan 21, 2014 1:49 pm Post subject: Ducati rectifier/regulators

Oops and rectify... 



[quote] On Jan 21, 2014, at 4:42 PM, Pete <peterz(at)zutrasoft.com> wrote:

 

 From that schematic, it is indeed a simple waste/dump regulator,with the two failing diodes being there to prevent battery from reverse feeding during the dumps.  It is pretty silly that they undersized them for rated alternator generating current capacity.  "Certified". Wow.

 

 Cheers,

 Pete

 

> On Jan 21, 2014, at 4:12 PM, Bill Henderson <europa10(at)bellsouth.net> wrote:

> 

> As info.....

> 

> I opened up one of the Rotax regulators a friend gave me after a failure.  The two diodes were bad and were open so paralleling them with external diodes does seem to be a viable option. Relatively cheap for the cost of the diodes and a heat sink.  No modification to the existing regulator required.  Attached is the fix I obtained from another website.  Just need to join the diodes to the B and two G terminals.

> 

> Just my two cents worth.....

> 

> Bill

> A010 Classic Monowheel

> Still building.

> 

> 

> 

> 

>> On 1/21/2014 3:02 PM, Jan de Jong wrote:

>> 

>> 

>> 

>> ad A:

>> Don't agree. The only stress would be somewhat higher reverse voltage. The Ducati R/R is not a shunt regulator.

>> 

>> ad B:

>> Agree, but the thyristors are more stressed than the diodes. They drop a little more voltage and dissipate more heat.

>> On the other hand, the custom fitting of the diode pills could be more uncertain than the standard fitting of the thyristors (TO220 I believe).

>> 

>> Parallelling the diodes with external ones is possible. They would require a heat sink. Are the failure statistics clear about the diodes?

>> I think it would be better to get an R/R without issues.

>> 

>> Regards,

>> Jan

>> 

>> 

>>> On 1/21/2014 6:30 PM, Greg Fuchs wrote:

>>> 

>>> 

>>> 

>>> 

>>> Well, since the generator is not a two-legged 'phi' connection (i.e. the

>>> midpoint of the generator coil connected to the ground of the system or

>>> vehicle, then 'dumping to ground' may not be the term to use after all. Yes,

>>> I think that is correct.

>>> 

>>> Here are the two main failure modes of the Ducatti regulator as I see it..

>>> 

>>> A) If the aircraft has a very low load usage (i.e. no lights, no

>>> instruments, etc.), the scr's are stressed and 'may' fail eventually. If

>>> this happens, the Ducatti is unrecoverable.

>>> 

>>> B) If the aircraft has a very high load usage (using up most of its 15-18

>>> amps), the output diodes are stressed and probably will fail eventually,

>>> which is backed up by historical data gathering (they fail a lot at high

>>> loads per many forum users). The Ducatti would then be recoverable by

>>> placing 25 Amp or higher diodes on the external terminals as referenced

>>> earlier.

>>> 

>>> Scenario (A) is unlikely, since everyone likes power-hungry instruments and

>>> the like, where scenario (B) is the most likely for the same reason.

>>> 

>>> Thus, if someone wants to 'beef up' their ducatti, then they have the option

>>> to place the external diodes. I guess it doesn't matter what kind, as long

>>> as they can withstand the current from the generator. They will either help

>>> the internal diodes survive almost forever, or take over for them when they

>>> fail (It depends on the turn-on points between the internal and external

>>> diodes).

>>> 

>>> Jan, do you agree with this?

>>> 

>>> Best Regards,

>>> Greg

>>> 

>>> --

gregoryf.flyboy(at)comcas
Guest

Posted: Tue Jan 21, 2014 11:54 pm Post subject: Ducati rectifier/regulators

Bill-

It's nice to have real-world evidence of the diodes going out. That's great

detailed info on their replacement, that may come in handy for some of us,

thanks. 



--

gregoryf.flyboy(at)comcas
Guest

Posted: Wed Jan 22, 2014 12:06 am Post subject: Ducati rectifier/regulators

Maybe not so fast about waste/dump conclusions..

When I built my motorcycle regulator about 5 years ago, I made it in the

shunt configuration, or the simple waste/dump. It still works great to this

day. It is very similar to the example in Nigel's document (which I plan to

go over in more detail about the Mosfet versions of regulators), except I

used an actual programmable shunt regulator IC to control the high-power

stage (a simple thing..it modeled like a zener with an amazing amount of

math to come up with the programming resistors, for what it is).



Unfortunately in this case, I didn't pay attention to the orientation of the

scr's in the Ducatti regulator.

When I went to prove to myself that they were shorting out the windings of

the generator to itself (similar to connecting the two outputs together), I

could only prove what Jan de Jong has been saying all along..that they

weren't. Thus, seems to not be a shunt configuration after all.



One downfall in this configuration..with no load on the generator, its AC

potential may have the ability to climb quite high. In hindsight, I guess

that was talked about in this thread ..30 volts...(42 volts peak?), but I

assumed probably incorrectly, that the measurement was made without a

regulator connected. 

I wouldn't prefer those high voltages flying around...increasing the danger

of getting zapped and the dielectric needs of the components, but it is what

it is. In this configuration, the diode AND the scr are conducting at once,

to carry current to the load...increasing the needs on the heat sink.  



Still, if the output diodes are a common failure mode, and with the cost of

replacements...it would be nice to see some of these things come back to

life. Stick it to the man..or the overpriced dealer, heehee.



--

grahamsingleton(at)btinte
Guest

Posted: Wed Jan 22, 2014 1:53 am Post subject: Ducati rectifier/regulators

I haven't followed this thread much, but isn't the big capacitor essential 

for the Ducatti system/ The big C prevents voltages from rising and

acts as a dump/battery or has my memory tricked me again?

Graham





        From: Greg Fuchs <gregoryf.flyboy(at)comcast.net>

 To: europa-list(at)matronics.com 

 Sent: Wednesday, 22 January 2014, 8:04

 Subject: RE: Re: Ducati  rectifier/regulators

  

 

--> Europa-List message posted by: "Greg Fuchs " <gregoryf.flyboy(at)comcast.net (gregoryf.flyboy(at)comcast.net)>



Maybe not so fast about waste/dump conclusions..

When I built my motorcycle regulator about 5 years ago, I made it in the

shunt configuration, or the simple waste/dump. It still works great to this

day. It is very similar to the example in Nigel's document (which I plan to

go over in more detail about the Mosfet versions of regulators), except I

used an actual programmable shunt regulator IC to control the high-power

stage (a simple thing..it modeled like a zener with an amazing amount of

math to come up with the programming resistors, for what it is).



Unfortunately in this case, I didn't pay attention to the orientation of the

scr's in the Ducatti  regulator.

When I went to prove to myself that they were shorting out the windings of

the generator to itself (similar to connecting the two outputs together), I

could only prove what Jan de Jong has been saying all along..that they

weren't. Thus, seems to not be a shunt configuration after all.



One downfall in this configuration..with no load on the generator, its AC

potential may have the ability to climb quite high. In hindsight, I guess

that was talked about in this thread ..30 volts...(42 volts peak?), but I

assumed probably incorrectly, that the measurement was made without a

regulator connected. 

I wouldn't prefer those high voltages flying around...increasing the danger

of getting zapped and the dielectric needs of the components, but it is what

it is. In this configuration, the diode AND the scr are conducting at once,

to carry current to the load...increasing the needs on the heat sink.   



Still, if the output diodes are a common failure mode, and with the cost of

replacements...it would be nice to see some of these things come back to

life. Stick it to the man..or the overpriced dealer, heehee.



--

gregoryf.flyboy(at)comcas
Guest

Posted: Wed Jan 22, 2014 2:35 am Post subject: Ducati rectifier/regulators

The capacitor is necessary and similar to the  battery will act as a stabilizer, but is not meant to prevent the  voltage from rising. That is the 'dumping' we are talking about. Dumping voltage  is not a function of the capacitor.

   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM  SINGLETON

Sent: Wednesday, January 22, 2014 1:50 AM

To:  europa-list(at)matronics.com

Subject: Re: Re: Ducati  rectifier/regulators

 I  haven't followed this thread much, but isn't the big capacitor essential 

for  the Ducatti system/ The big C prevents voltages from rising and

acts as a  dump/battery or has my memory tricked me again?

Graham

     From: Greg  Fuchs <gregoryf.flyboy(at)comcast.net>

To: europa-list(at)matronics.com 

Sent: Wednesday, 22 January 2014,  8:04

Subject: RE: Europa-List:  Re: Ducati rectifier/regulators

--> Europa-List message posted by: "Greg Fuchs  " <gregoryf.flyboy(at)comcast.net (gregoryf.flyboy(at)comcast.net)>

Maybe  not so fast about waste/dump conclusions..

When I built my motorcycle  regulator about 5 years ago, I made it in the

shunt configuration, or the  simple waste/dump. It still works great to this

day. It is very similar to  the example in Nigel's document (which I plan to

go over in more detail about  the Mosfet versions of regulators), except I

used an actual programmable  shunt regulator IC to control the high-power

stage (a simple thing..it  modeled like a zener with an amazing amount of

math to come up with the  programming resistors, for what it is).

Unfortunately in this case, I  didn't pay attention to the orientation of the

scr's in the Ducatti  regulator.

When I went to prove to myself that they were shorting out the  windings of

the generator to itself (similar to connecting the two outputs  together), I

could only prove what Jan de Jong has been saying all  along..that they

weren't. Thus, seems to not be a shunt configuration after  all.

One downfall in this configuration..with no load on the generator,  its AC

potential may have the ability to climb quite high. In hindsight, I  guess

that was talked about in this thread ..30 volts...(42 volts peak?), but  I

assumed probably incorrectly, that the measurement was made without  a

regulator connected. 

I wouldn't prefer those high voltages flying  around...increasing the danger

of getting zapped and the dielectric needs of  the components, but it is what

it is. In this configuration, the diode AND  the scr are conducting at once,

to carry current to the load...increasing the  needs on the heat sink.  

Still, if the output diodes are a common  failure mode, and with the cost of

replacements...it would be nice to see  some of these things come back to

life. Stick it to the man..or the  overpriced dealer, heehee.

--

Remi Guerner

Joined: 14 Dec 2010
Posts: 284

Posted: Wed Jan 22, 2014 3:18 am Post subject: Re: Ducati rectifier/regulators

Very interesting discussion on the regulator-rectifier. After my first Ducati regulator failed at about 150 hours, I designed some simple installation improvements in order to increase the reliability of the unit.

I believe the main problem is to dissipate the heat. On the Europa, the regulator is bolted to a composite structure which cannot act as a heat sink. So it is necessary to duct cold outside air to the unit fins. I use SCAT ducting to take the air from the front of the cowling to a plenum riveted to the Ducati fins. 

Another issue is grounding:  the unit being bolted through a weak glassfiber/foam sandwich structure, there is no way you can compress the ring terminal enough to make a good ground connection. Now my ground wire is bolted to one of the regulator fins using a separate bolt which can be torqued properly. See attached picture.

Then there is the warning light which occasionally was giving false information while the bus voltage was just right. I have since disconnected the L terminal and installed a separate low/high voltage monitor (B&C).

The replacement Ducati regulator I installed more than ten years ago has now close to 1000 hours. May be because I have been carrying a spare unit since the original one failed?   

Remi Guerner

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h&jeuropa

Joined: 07 Nov 2006
Posts: 654

Posted: Wed Jan 22, 2014 4:58 am Post subject: Re: Ducati rectifier/regulators

The problem with external diodes as mentioned above is that the heat sink they mount to will be at battery voltage.  A better solution is to use a bridge rectifier so the diodes are insulated from the mounting package.  Then the heat sink will be electrically independent.  Such a bridge is a Vishay 36MB120A ($.  This is a 35 amp, 1200 volt device which is similar to the original Ducatti diodes.  I plan to install this Spring.



Jim Butcher

N241BW

tonyrenshaw268(at)gmail.c
Guest

Posted: Wed Jan 22, 2014 9:59 am Post subject: Ducati rectifier/regulators

Hi Remi,

Thank you for a vanilla way of dealing with the problem.

Tony Renshaw

Sent from my iPad



 	  Quote: 	
		   On 22 Jan 2014, at 3:18 am, "Remi Guerner" <air.guerner(at)orange.fr> wrote:

 

 

 

 Very interesting discussion on the regulator-rectifier. After my first Ducati regulator failed at about 150 hours, I designed some simple installation improvements in order to increase the reliability of the unit.

 I believe the main problem is to dissipate the heat. On the Europa, the regulator is bolted to a composite structure which cannot act as a heat sink. So it is necessary to duct cold outside air to the unit fins. I use SCAT ducting to take the air from the front of the cowling to a plenum riveted to the Ducati fins. 

 Another issue is grounding:  the unit being bolted through a weak glassfiber/foam sandwich structure, there is no way you can compress the ring terminal enough to make a good ground connection. Now my ground wire is bolted to one of the regulator fins using a separate bolt which can be torqued properly. See attached picture.

 Then there is the warning light which occasionally was giving false information while the bus voltage was just right. I have since disconnected the L terminal and installed a separate low/high voltage monitor (B&C).

 The replacement Ducati regulator I installed more than ten years ago has now close to 1000 hours. May be because I have been carrying a spare unit since the original one failed?   

 Remi Guerner

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=417404#417404

 

 

 

 

 Attachments: 

 

 http://forums.matronics.com//files/p8230007a_100.jpg

gregoryf.flyboy(at)comcas
Guest

Posted: Thu Jan 23, 2014 11:02 am Post subject: Ducati rectifier/regulators

Using an encapsulated bridge seems like a great plan, and can easily be

found at almost any electrical supplier. 



They have Fast-on connectors, for easy integration with the Ducati (finally

got the spelling right). These parts also seem to have the right qualities: 



GBPC35 series Bridge Rectifier from Fairchild or the GBPC35A from Vishay (be

sure not to get the 'w' version, which has wires instead of fast-ons). One

could go with higher amperage, but the price seems to exponentially increase

if going much higher, and these are only about $3.00 for the first and a few

more for the second. Besides, only 2 of the 4 diodes are to be used. If it

ever fails, the other two diodes can be accessed. It's like having a spare

part being carried around at all times, so according to Remi, I guess that

means the first two will never fail.  ...Its a Murphy work-around #) 



Of course, it would still be good to have a few more reports from people

that have breathed life back into their regulators, just to prove that the

diodes are a common failure. That could be done with a completely burned out

regulator, two 10-cent silicon diodes from Radio Shxxx(Spares?) and a small

load, such as a light bulb...



Greg, A050

 

 



--

budyerly(at)msn.com
Guest

Posted: Thu Jan 23, 2014 9:13 pm Post subject: Ducati rectifier/regulators

Jan, and others,

Thanks for cleaning up my jargin.  In my feeble mind the thyrister disconnect is just dumping the power from the output.  Your explanation shows true knowledge of these components.   Whether it dumps or shorts or snorts, I agree that the problem is not worth repairing.  One could try to fix the Ducati, but as you say, if its broke, it is best to just replace it...  

 

Great idea from Kevin on putting the regulator on the 914 duct, or Remi's idea on an aluminum plate to absorb more heat.

 

However, what is the track record on the others using the GR6 or SH.  Without testing on a plane with known current draw, specifics on the RPM variations, battery condition etc. what is good for one may not work for all.  I know Paul has a fairly high draw aircraft (probably close to 15 amps), and some extra data would be nice...   However, I would like to see all of us not throw good money after bad or waste our time.  My plane just doesn't draw enough power to kill the Ducati so I must experiment on more electrically thirsty planes and listen to the lessons of others.  

 

I have now completed quite a number of aircraft, nearly all are running and working well.  From the electric side, it seems to me we should set a basic guideline for what to do electrically from the bus supply side for our new owners/builders.  Lord knows I have made many compromises using everything from split busses to dual alternators to get enough power to run stuff.

 

Every client/builder has his own desires on the type of equipment he wants, but usually doesn't have a clue on what really happens when all the toys get turned on.  The Rotax install manual gives one the impression the new Rotax/Ducati combo is a 22 amp 14.2 volt system above 1000 + 250 RPM.  I haven't seen that output at 2000 RPM except before the avionics were turned on. (That data was upgraded from the old 13.6 above 2000RPM from my old regulator).

 

We know the Rotax / Jabiru charging systems do not produce enough power to charge, at low RPM as during taxi, pattern, and landing roll out with all the stuff on.  There is nothing worse than an electrical system that is depleted due to low RPM running with a slightly old battery, and on final, when you key the mic, the radio shuts down and EFIS reboots due to a low battery condition brought on by running only 30 minutes at or below 4000 RPM.  On landing roll out you have to shut down everything and run the engine up to talk on the radio.  My rule of thumb is "the Rotax charging system  can only produce 15 amps at 13 volts above 4000 RPM" (at 18 amps the voltage just begins to drop off a bit) and electrical power requirements must be reduced below 4000 RPM or you must have a battery of sufficient capacity to supply the deficiency of the charge system.   

 

I build a power requirement sheet with each panel I build or supervise.  That works great at cruise, but doesn't give the full picture at low RPM/High current draw phases of flight, so we hope the battery was fully charged well prior to pattern entry.

 

If you are an amp zealot, but still want an aux fuel pump, pitot heat, 100 watt landing light, strobes, heavy draw radio (Garmin 430 type), Aux Radio, Mode S transponder continuously working, autopilot, stereo high quality music system, external power plugs for our phones, I-pads and inflight video system,  the Rotax charging system is not going to hack it.

 

Perhaps in the situation above, it would be prudent for a 914 builder (914 can draw 11 amps on its own with both pumps running) to consider a belt driven alternator of 40 amps, and simply redo the cowl front and keep the Rotax as a backup in case of belt failure.

 

If you build a 912S airplane with all LED lighting, Garmin 255 or Becker Com, Simple digital Transponder, Aux Boost, and maybe an autopilot for cruise only and a paper map, then the Rotax / Ducati should be fine.  The GR6 or SH may be better and longer lasting to boot.  In my opinion the Rotax system can't put out much more than 15 amps or so and as the current increases, the voltage output starts to diminish (at least it does in my poor old airplane) .

 

Just my thoughts.

Bud

 

 



 



 	  Quote: 	
		   Date: Mon, 20 Jan 2014 16:40:25 +0100

 From: jan_de_jong(at)casema.nl

 To: europa-list(at)matronics.com

 Subject: Re: Re: Ducati rectifier/regulators

 

 --> Europa-List message posted by: Jan de Jong <jan_de_jong(at)casema.nl>

 

 Re two-phase bridge rectifier/regulator.

 The 2 thyristors in the rectifier bridge do not short the AC input or 

 "dump" anything.

 On the contrary, they disconnect the DC output from the AC input when 

 the output voltage threatens to exceed the set voltage.

 All output current passes through one branch of one diode and one 

 thyristor in series half the time and through the other identical branch 

 also half the time.

 Heat development is proportional to the output current and the voltage 

 drop across a branch.

 Voltage drops increase somewhat with current, so heat development 

 increases more than linearly with output current.

 In the Ducati device the diode is reportedly a MR2510 pill (typically 

 0.75V at 10A, 0.8V at 20A), the thyristor can be a 2N6504 (typically 

 1.1V at 10A, 1.3V at 20A).

 So at 10A the two branches of the bridge are each expected to generate 

 0.5 x  (7.5 + 11) = 9.25W (total 18.5W) of heat.

 And at 20A the two branches of the bridge are each expected to generate 

 0.5 x (16 + 26) = 21W (total 42W) of heat.

 

 (

 a failure mode for the Ducati device is reportedly the loss of 

 continuity of a diode pill attachment through thermal cycling; fitting 

 external parallel diodes has been proposed as a solution; replacing the 

 whole device seems more sensible

 )

 

 Cheers,

 Jan de Jong

 

&g=======================
	


&g=======

 	  Quote: 	
		   

 

 


	


  		 	   		  

  [quote][b]

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