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generator question

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skidmk

Joined: 19 Nov 2007
Posts: 171
Location: Ottawa, Ontario

Posted: Sat Nov 14, 2009 9:03 am Post subject: generator question

recently installed the horizon P1000 tach,,, it shuts down periodically when full power/rpm is engaged... and it restarts itself once power is pulled back from full.



horizon says its because I'm generating more than 32vdc and the tach is protecting itself by shutting down then restarting when voltage falls back to normal.



Would this be an indicator that my generator is starting to go?  Or the regulator?



thanks



Mike

_________________
Mike "Skidmk" Bourget
Ottawa, Ontario

keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Sun Nov 15, 2009 7:41 pm Post subject: Re: generator question

Hey Hoser,



Mark Bitterlich  seems to be the electron guru around here and if you say some nice things about  the most elite fighting force in the world he might answer. I don't think it's unrealistic to have voltage spikes. Would it be possible to put a transorb surge protector in the power lead for your tach? (not the P-lead connection).  Don't know, but I know they are cheap and you can get them at radio shack. Glad to hear the instrument has some built in protection..pretty pricey



What you been up to?



Semper Fi,



Wiz

dsavarese0812(at)bellsout
Guest

Posted: Mon Nov 16, 2009 3:52 am Post subject: generator question

The problem Mike is experiencing sounds more like a voltage  regulator issue.  If you have a digital volt meter, connect it to the 28  volt buss.  Run the engine up and see if the voltage stabilizes after the  engine RPM gets above about 1200 RPM.  I don't know if you have a 52 or a  CJ.  If it's a 52, there is a rheostat (slotted screw) on the left side by  the flap lever that you can adjust the voltage level.  It should read  about 28 volts when the engine is running between about 1200 rpm (41%) and WOT  (100%) or 2900 RPM.  You can also push the Volt meter button in and read  VOLTS on the inner scale of the instrument (the small gold  letters).

 Dennis

 [quote]   ---

keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Mon Nov 16, 2009 6:34 am Post subject: Re: generator question

Good point Dennis considering when this happens. For the record I still think that anything that creates electricity can create a voltage spike. Might not trash your stuff outright but overtime will ruin it. If I had some fancy EFIS on my plane I'd sure have a surge protector on it. 



Of course I could be wrong!  



K

yakplt(at)yahoo.com
Guest

Posted: Mon Nov 16, 2009 6:35 pm Post subject: generator question

Hi Keith, thanks for the compliment.  My professional field is indeed electronics, with RF as the strong suite, but let me tell you, there are a few guys hanging around this list that are smart enough to keep their mouth shut, but never-the-less are highly regarded experts in their field.  Rob Rowe is one, and when he opens his mouth, I listen closely.  Another gent owns his own company, has a PhD, and develops a whole plethora of products.  That said, just about any time in my life I feel I am starting to get pretty good at something, I get a lesson in humility from someone who is REALLY good.  .  

  

 Also you're right.  Say a few good words about the USMC, and I will always come out of the wood-work.  I have been absent from this list for awhile as I have been  going to school on long and short baseline interferometry.  Another lesson in how much more math I need.  

  

 In answer to the original question that dealt with the over-voltage condition shutting down the tach.  Hmmm..... seems unlikely to me.  The YAK series of aircraft has a built in over-voltage device ALREADY.  If you exceed 32 volts, it trips a circuit breaker and removes field excitation to the generator, effectively shutting it off.  Further, even if that was defective, running over 32 volts DC in your aircraft for any effective period of time would pretty much boil the electrolyte out of your batteries pretty darn quick.  Then we have Dennis's comments, which were are as usual, dead on.  Of course you can check your actual voltage right in the cockpit with your volt/ammeter!  Only takes a second to do that.  So couple that check, with the built in over-voltage protection our aircraft have, and I have a hard time really believing the problem with the tach is an over-voltage condition.  

  

 That said, there are a lot of other issues that are possible.  I would suggest first that the gent check his battery voltage BEFORE he goes flying.  After the aircraft has sat for awhile, check it and make sure it is 24 volts and not less.  If it is, then he has bad batteries, and the generator is going to be trying to constantly charge them.  This will result in a higher noise output from the generator.  The more current it produces, the more noise it will create.  This is a real shotgun comment of course.  But it is a valid test.  

  

 If I were to make a wild ass guess, it would be that this particular tach might indeed be "not quite right".   As in... the people that make it already admit  that it has an over-voltage shut-down mode.  That means two things can make it shut off.  

  

 1.  An aircraft over-voltage. 

 2.  Something wrong with the over-voltage circuit in the tach itself!  

  

 It might be number 2.  

  

 Hey, if you really want to know... just do exactly as Dennis suggested.  Put a good voltmeter on the DC line (the battery is a good place), and measure the voltage before you start, then after with the engine run up as far as you want to stand there and get beat to death by the prop blast!  But... get it up to about 75% or so at least.  Make sure that you watch the voltage come up to between 27-29 VDC and then STABILIZE.  In other words, it should reach a top limit and then STOP going UP as you increase engine RPM.  If it goes up steadily with engine RPM as you pass 75%, then something is bad wrong.  

  

 Voltage spikes:  Sure Keith, voltage spikes are indeed a bad thing, and in fact if you are concerned about them, adding a metal oxide varistor, or "trans-sorb" is indeed do-able.  However, voltage spikes are typically caused by large inductive loads.  The collapsing magnetic fields are the cause... and the biggest cause of those puppy dogs are STARTER MOTORS.  Something the Yak happens to be missing!   Honestly I can't think of too many inductive loads in a Yak (as in motors and stuff like them... INVERTER motor excepted!), so it comes back to the generator itself.  Generators don't usually put out nasty spikes, unless they are defective.  As in... really bad brushes.   

  

 Bad brushes could INDEED cause the problem noted with the TACH shutting off, but it is really low on my personal list of "could this be it?"   Normally if you have brushes THAT bad, you are going to hear it in your radio.  

  

 I've installed the P-1000 Tach on a few aircraft and have never seen this problem before, and my off the record personal guess is ... it may be the tach... but only if I personally ran all the other tests suggested first and they all came back negative.  

  

 Bottom line Keith, your comment about voltage spikes is perfectly true, but not really a concern (in my humble opinion) with the YAK model aircraft.  On the other hand, to prove your point as being VALID, you might be interested to know that in a lot of CESSNA model aircraft, they have two DC bus controls.  MAIN and AVIONICS.   When the starter motor is engaged, the AVIONICS BUS is turned OFF, for exactly the reason you were concerned about.  

  

 Best Regards, 

  

 Mark Bitterlich (writing from my hangar email account)  

  

 p.s.  Computing phase matched cells with simultanious short and long based interferometery is really stretching my remaining gray matter.  

  

 



--- On Mon, 11/16/09, keithmckinley <keith.mckinley(at)townisp.com> wrote:



  	  Quote: 	
		  

From: keithmckinley <keith.mckinley(at)townisp.com>

Subject: Re: generator question

To: yak-list(at)matronics.com

Date: Monday, November 16, 2009, 9:34 AM



 --> Yak-List message posted by: "keithmckinley" <keith.mckinley(at)townisp.com (keith.mckinley(at)townisp.com)>



Good point Dennis considering when this happens. For the record I still think that anything that creates electricity can create a voltage spike. Might not trash your stuff outright but overtime will ruin it. If I had some fancy EFIS on my plane I'd sure have a surge protector on it. 



Of course I could be wrong!  



K



  



--------

Keith McKinley

700HS

KFIT





Read this topic online here:



http://forums.matronics.co;          (And Get Some AWESOME FREE Gifts!); http://;                        -Matt Dralle, List Admin.p; --> 



	
 [quote][b]

keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Mon Nov 16, 2009 7:30 pm Post subject: Re: generator question

Great Post Mark,



Whenever I read posts from the technical Hardballers on this board (you, Dennis, Richard, Doug, et al) if feel like Forest Gump!



In any case, my Trons are in good shape and for what its worth both Mike and I have CJ's. I think Mike, being in Canada, is just too damn close to magnetic north and that's his problem...



BTW, this post will be going in my personal save file!



Thanks



Semper Fi Jarhead,



Wizard[/b]

jgriffint28(at)cox.net
Guest

Posted: Mon Nov 16, 2009 7:45 pm Post subject: generator question

To reinforce Mark's comment about checking the  battery, I found that my Horizon tach would intermittently shut down and recycle  when I had a bad battery. This has happened on 2 occasions. 

 Jim Griffin

  

  

  

 [quote]   ---

terrycalloway(at)mac.com
Guest

Posted: Tue Nov 17, 2009 6:15 am Post subject: generator question

Jim,I had my Horizon Tach just freeze a couple of times this year.  I had to land and shut down the engine before it worked again.  Did your go blank or freeze like mine?

tc





On Nov 16, 2009, at 9:45 PM, Jim Griffin wrote:

 	  Quote: 	
		  To reinforce Mark's comment about checking the battery, I found that my Horizon tach would intermittently shut down and recycle when I had a bad battery. This has happened on 2 occasions.

Jim Griffin

cjpilot710(at)aol.com
Guest

Posted: Tue Nov 17, 2009 7:53 am Post subject: generator question

In a message dated 11/17/2009 9:16:52 A.M. Eastern Standard Time,  terrycalloway(at)mac.com writes:

  

 No, that never happened to me before.  I wonder if you could have  brought the throttle back to idle, and momentary switched the mags to OFF, if  that could have precluded you from having to land?

  

 I know that my Horizon tach is connected to the back of the mag  switch.

  

 Jim

  

  	  Quote: 	
		  Jim,    I had my Horizon Tach just freeze a couple of times this year.  I    had to land and shut down the engine before it worked again.  Did your go    blank or freeze like mine?

   tc

   



   



         On Nov 16, 2009, at 9:45 PM, Jim Griffin wrote:

    	  Quote: 	
		            To reinforce Mark's comment about checking the      battery, I found that my Horizon tach would intermittently shut down and      recycle when I had a bad battery. This has happened on 2      occasions.

     Jim Griffin

      

      



	




= 	


 

  

  [quote][b]

terrycalloway(at)mac.com
Guest

Posted: Tue Nov 17, 2009 8:04 am Post subject: generator question

Good question.  I will try the mag if it happens again.  When it did happen I was local so landing was not and inconvenience.tc



On Nov 17, 2009, at 9:53 AM, cjpilot710(at)aol.com (cjpilot710(at)aol.com) wrote:

 	  Quote: 	
		     In a message dated 11/17/2009 9:16:52 A.M. Eastern Standard Time,  terrycalloway(at)mac.com (terrycalloway(at)mac.com) writes:

  

 No, that never happened to me before.  I wonder if you could have  brought the throttle back to idle, and momentary switched the mags to OFF, if  that could have precluded you from having to land?

  

 I know that my Horizon tach is connected to the back of the mag  switch.

  

 Jim

jgriffint28(at)cox.net
Guest

Posted: Tue Nov 17, 2009 6:45 pm Post subject: generator question

Hi Terry

 Mine went blank and then recycled back on.  Actually, the second time was because of a bad voltage regulator which fried the  battery. 

 Jim Griffin

 [quote]   ---

skidmk

Joined: 19 Nov 2007
Posts: 171
Location: Ottawa, Ontario

Posted: Fri Nov 20, 2009 11:38 am Post subject: Re: generator question

Wow,, thanks guys.. this stuff is way over my little Air Traffic Controller brain,,, but I have a guy  



interesting comment about he brushes though.  I installed a new radio this winter (microair)... and since then ATC has been sometimes complaining about radio noise.  Maybe it is the brushes... we'll look at all the possibilities and trouble shoot.



thanks



M

_________________
Mike "Skidmk" Bourget
Ottawa, Ontario

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