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Z16 Rotax 912 problem

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romaja

Joined: 24 Oct 2016
Posts: 4

Posted: Mon Oct 24, 2016 6:43 pm Post subject: Z16 Rotax 912 problem

I am performing the first few initial flight on a Rans S-20 Raven with a Rotax 912 ULS engine.



My wiring is based on the Z16 architecture using the S704-1 alternator OV disconnect and crowbar OV protection. So far everything is working just fine with one exception.



I noticed running the engine on the ground and once in the air that the 5 amp Gen breaker popped. This is the breaker between the main bus and the master switch. On both occasions, I reset it and it did not pop again.



I am using the S700 2-10 switch as my master switch. The battery I am using is an EarthX Lithium Iron 680.



Whilst in flight I was testing a coolant heater fan and when placed on high will draw 8 amps. Moments later I noticed the 5 amp breaker had popped. Possibly a coincidence.



Normal amp draw in flight is around 7 or 8 amps without  this heater running and a charged battery.



 Any ideas what is causing this CB to pop?



Thanks

Jim

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user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Tue Oct 25, 2016 4:22 am Post subject: Re: Z16 Rotax 912 problem

The over-voltage module is tripping the circuit breaker.  Options are:

Replace the O.V. module with one not so sensitive.

Remove the O.V. module.

Put a filter in series with the O.V. module consisting of an inductor and capacitor.

Leave it as is and reset the breaker whenever it trips.

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_________________
Joe Gores

romaja

Joined: 24 Oct 2016
Posts: 4

Posted: Tue Oct 25, 2016 6:21 am Post subject: Re: Z16 Rotax 912 problem

Thank you very much. Do you know the filter and inductor I would need?

A link possibly?.

I also could remove the OV module. I could use my Dynon Skyview to alert me of an OV condition. Not sure if it would alert me soon enough to prevent damage.



Also, to confirm. You are talking about the 704 module and not the Crowbar?



Best,



Jim

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 25, 2016 7:26 am Post subject: Z16 Rotax 912 problem

At 09:43 PM 10/24/2016, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "romaja" <abc6284(at)mac.com>



 I am performing the first few initial flight on a Rans S-20 Raven with a Rotax 912 ULS engine.



 My wiring is based on the Z16 architecture using the S704-1 alternator OV disconnect and crowbar OV protection. So far everything is working just fine with one exception.



 I noticed running the engine on the ground and once in the air that the 5 amp Gen breaker popped. This is the breaker between the main bus and the master switch. On both occasions, I reset it and it did not pop again.



 I am using the S700 2-10 switch as my master switch. The battery I am using is an EarthX Lithium Iron 680.



 Whilst in flight I was testing a coolant heater fan and when placed on high will draw 8 amps. Moments later I noticed the 5 amp breaker had popped. Possibly a coincidence.



 Normal amp draw in flight is around 7 or 8 amps without  this heater running and a charged battery.



 



  Any ideas what is causing this CB to pop? 	


   Sounds like a 'twitchy' ov module. If you'll

   send it to me I'll check it an correct as

   necessary. It's not 'unsafe' to fly without

   it in the interim.



   

   Bob Nuckolls

   PO Box 130

   Medicine Lodge, KS  67104-0130



 

   Bob . . .

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romaja

Joined: 24 Oct 2016
Posts: 4

Posted: Tue Oct 25, 2016 10:49 am Post subject: Re: Z16 Rotax 912 problem

Sounds like a 'twitchy' ov module. If you'll

   send it to me I'll check it an correct as

   necessary. It's not 'unsafe' to fly without

   it in the interim.



   

   Bob Nuckolls

   PO Box 130

   Medicine Lodge, KS  67104-0130



 

   Bob . . .[/quote]



Thank you Bob,



I will send it to you.

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user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Tue Oct 25, 2016 1:53 pm Post subject: Re: Z16 Rotax 912 problem

Jim, take Bob up on his offer.  I am not familiar with a 704 module, unless you are talking about the relay, which is very unlikely to trip the breaker.  Since you have a SkyView, can you download the data log and analyze it?  MS Excel can search for the maximum voltage.  If the voltage really is high, then the crowbar over voltage module is doing its job by tripping the breaker.  I can not recommend a filter, usually they do not help much.  Search Amazon for "Noise Filter".  Many modern avionics can be powered by either 14 or 28 volts, so over voltage is not as big of a concern as it used to be.  On the other hand, the Lithium battery does not like over voltage.  Do you have high and low voltage alarms set up in the SkyView?

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_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Oct 25, 2016 6:00 pm Post subject: Z16 Rotax 912 problem

At 04:53 PM 10/25/2016, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 Jim, take Bob up on his offer.  I am not familiar with a 704 module, unless you are talking about the relay, which is very unlikely to trip the breaker. 	




  Here are the details



  http://tinyurl.com/japwbsu



  Yes, the S704 is a relay used in conjunction with

  a crowbar ov module in Rotax installations . . .



  http://tinyurl.com/7vp9g4e



 

  	  Quote: 	
		   Since you have a SkyView, can you download the data log and analyze it?  MS Excel can search for the maximum voltage.  If the voltage really is high, then the crowbar over voltage module is doing its job by tripping the breaker. 	




 I have had a FEW . . . meaning two or three in 20 years . . .

 instances where switching some appliance on or off in a

 composite aircraft would trip the AEC9003 or the B&C clone

 of this device.



 A little background on ov protection products . . . the very

 first product I designed for TC aircraft was about 1974 and

 I had just gone to work for Electro-Mech, Inc. in Wichita. It

 was an over-voltage RELAY and the design goal of the moment was

 that a step increase of sensed voltage from normal (14.2) to

 20.0 volts would cause a trip in 100mS plus or minus perhaps

 10mS.



 That was the 'comfortable' requirement embraced by the TC

 aircraft industry at that time. Yet, even in 1974, a DO160

 qualified, 14v appliance had to withstand 20 volts for ONE

 SECOND, and 40 volts for 100mS.



 Having roots of design philosophy fertilize in that

 environment, my OV protection designs have tended to

 run on, shall we say, the 'twitchy' side of trip sensitivity.



 On the whole, not a terrible decision. Since that time, perhaps

 10,000 ov relays (and crowbar ov modules) have been designed

 and manufactured to that design philosophy . . . and nuisance

 trips by the exceptional transient event have been VERY rare.

 But I have personally attend to two such events and there

 have, no doubt, be a few others.



 The 'fix' has been to modify the CbOVM for those airplanes

 with longer time constants  . . . typically 2 to 5 times

 the original design goal.



 ALL future ov protection systems originating from this

 writer's CAD system will shoot for a 500mS response to

 a 20 volt event and a 50mS response to a 40v event.



 Further, timing will no longer be controlled by RC time

 constants and trip-voltage of some semiconductor. Future

 designs are microprocessor sampled and time under software

 control.



 

  	  Quote: 	
		    I can not recommend a filter, usually they do not help much.  Search Amazon for "Noise Filter".  Many modern avionics can be powered by either 14 or 28 volts, so over voltage is not as big of a concern as it used to be.  On the other hand, the Lithium battery does not like over voltage.  Do you have high and low voltage alarms set up in the SkyView? 	


 He is very unlikely to see a REAL ov event on the

 data storage system. Since the even occurs in response

 to some switching event, we're 99% sure that the 'problem'

 originates with a singularly noisy event driving a ov

 protection design with some rather ancient roots in

 legacy operating philosophies.



 So yes, the 'fix' is to simply slow down the OV protection

 sense profile by a factor of 4 or 5 times which is still

 very conservative compared to DO-160 qualification requirements.



 

 

   Bob . . .

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romaja

Joined: 24 Oct 2016
Posts: 4

Posted: Fri Oct 28, 2016 6:04 pm Post subject: Re: Z16 Rotax 912 problem

 	  user9253 wrote: 	
		  Jim, take Bob up on his offer.  I am not familiar with a 704 module, unless you are talking about the relay, which is very unlikely to trip the breaker.  Since you have a SkyView, can you download the data log and analyze it?  MS Excel can search for the maximum voltage.  If the voltage really is high, then the crowbar over voltage module is doing its job by tripping the breaker.  I can not recommend a filter, usually they do not help much.  Search Amazon for "Noise Filter".  Many modern avionics can be powered by either 14 or 28 volts, so over voltage is not as big of a concern as it used to be.  On the other hand, the Lithium battery does not like over voltage.  Do you have high and low voltage alarms set up in the SkyView? 	




Yes I have high voltage and low voltage set on my Skyview. I will check to see where I set them as I cant recall.



I checked the data logs and they dont show any over voltage conditions.



Thanks

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