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OVM-14 question

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nuckolls.bob(at)aeroelect
Guest

Posted: Tue Nov 26, 2019 9:33 am Post subject: OVM-14 question

At 01:30 PM 11/25/2019, you wrote:

  	  Quote: 	
		  Sorry to bother you off the list but I couldn't get logged in. I know you prefer questions to be posted so everybody can learn. feel free to post this if you like. Hope you have an great Thanks giving week! 	


  Thank you sir.



 

  	  Quote: 	
		  I'm doing 2 electrical energized field alternators (small frame 53A), one adjustable regulator,Â  one non adjustable regulator, 2 OVM-14 modules, one battery off the Z13/8 dwg. 	


  If you have two, hefty alternators then

  Z12 is the better option.



 

  	  Quote: 	
		  I have two 5 amp Klixon circuit breakers for the fields. 	


  Okay



 

  	  Quote: 	
		  My question is about the OVM-14. If both alternators were in output mode due to low voltage then one went into over voltage, how do I get the OVM-14s to only trip the circuit for the one that is over voltage? It seems like both field circuits would trip the CB. 	


  You don't run both alternators at the same time.

  Run only the main alternator until you get a

  low volts warning then turn main alternator

  OFF, aux alternator ON>



  	  Quote: 	
		  Second question is about eBus.



 I have Circuit breakers for many things. Instead of a second bus, I was thinking of a momentary switch connected to the load side of all things that could be shut off in battery saving mode. Pressing the switch would trip the breakers for unnecessary items which could be individually turned back on if required. would a switch be adequate or should a 704-1 relay be used to handle the shorting load. 	


  I'm curious as to why Z12 is un-attractive as-published?

  What shortcomings in Z12 beg rectification?



  Also, aside from crow-bar field breakers, why

  not fuse blocks? Breakers take up space, add

  a lot of fabrication/installation labor, don't

  work any better than a fuse. 99.9% of all breakers

  installed at the factory go to the scrap yard

  never having been required to keep a wire from

  smoking. Why so much investment in a feature

  that adds nothing to the utility/reliability

  of your airplane?



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Nov 26, 2019 12:43 pm Post subject: OVM-14 question

At 01:30 PM 11/25/2019, you wrote:

  	  Quote: 	
		  Sorry to bother you off the list but I couldn't get logged in. I know you prefer questions to be posted so everybody can learn. feel free to post this if you like. Hope you have an great Thanks giving week! 	


  Thank you sir.



 

  	  Quote: 	
		  I'm doing 2 electrical energized field alternators (small frame 53A), one adjustable regulator,Â  one non adjustable regulator, 2 OVM-14 modules, one battery off the Z13/8 dwg. 	


  If you have two, hefty alternators then

  Z12 is the better option.



 

  	  Quote: 	
		  I have two 5 amp Klixon circuit breakers for the fields. 	


  Okay



 

  	  Quote: 	
		  My question is about the OVM-14. If both alternators were in output mode due to low voltage then one went into over voltage, how do I get the OVM-14s to only trip the circuit for the one that is over voltage? It seems like both field circuits would trip the CB. 	


  You don't run both alternators at the same time.

  Run only the main alternator until you get a

  low volts warning then turn main alternator

  OFF, aux alternator ON>



  	  Quote: 	
		  Second question is about eBus.



 I have Circuit breakers for many things. Instead of a second bus, I was thinking of a momentary switch connected to the load side of all things that could be shut off in battery saving mode. Pressing the switch would trip the breakers for unnecessary items which could be individually turned back on if required. would a switch be adequate or should a 704-1 relay be used to handle the shorting load. 	


  I'm curious as to why Z12 is un-attractive as-published?

  What shortcomings in Z12 beg rectification?



  Also, aside from crow-bar field breakers, why

  not fuse blocks? Breakers take up space, add

  a lot of fabrication/installation labor, don't

  work any better than a fuse. 99.9% of all breakers

  installed at the factory go to the scrap yard

  never having been required to keep a wire from

  smoking. Why so much investment in a feature

  that adds nothing to the utility/reliability

  of your airplane?



 

 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Nov 26, 2019 7:38 pm Post subject: OVM-14 question

At 01:30 PM 11/25/2019, you wrote:

  	  Quote: 	
		  Sorry to bother you off the list but I couldn't get logged in. I know you prefer questions to be posted so everybody can learn. feel free to post this if you like. Hope you have an great Thanks giving week! 	


  Thank you sir.



 

  	  Quote: 	
		  I'm doing 2 electrical energized field alternators (small frame 53A), one adjustable regulator,Â  one non adjustable regulator, 2 OVM-14 modules, one battery off the Z13/8 dwg. 	


  If you have two, hefty alternators then

  Z12 is the better option.



 

  	  Quote: 	
		  I have two 5 amp Klixon circuit breakers for the fields. 	


  Okay



 

  	  Quote: 	
		  My question is about the OVM-14. If both alternators were in output mode due to low voltage then one went into over voltage, how do I get the OVM-14s to only trip the circuit for the one that is over voltage? It seems like both field circuits would trip the CB. 	


  You don't run both alternators at the same time.

  Run only the main alternator until you get a

  low volts warning then turn main alternator

  OFF, aux alternator ON>



  	  Quote: 	
		  Second question is about eBus.



 I have Circuit breakers for many things. Instead of a second bus, I was thinking of a momentary switch connected to the load side of all things that could be shut off in battery saving mode. Pressing the switch would trip the breakers for unnecessary items which could be individually turned back on if required. would a switch be adequate or should a 704-1 relay be used to handle the shorting load. 	


  I'm curious as to why Z12 is un-attractive as-published?

  What shortcomings in Z12 beg rectification?



  Also, aside from crow-bar field breakers, why

  not fuse blocks? Breakers take up space, add

  a lot of fabrication/installation labor, don't

  work any better than a fuse. 99.9% of all breakers

  installed at the factory go to the scrap yard

  never having been required to keep a wire from

  smoking. Why so much investment in a feature

  that adds nothing to the utility/reliability

  of your airplane?



 

 

   Bob . . .

jdpnm

Joined: 26 Nov 2019
Posts: 6

Posted: Wed Dec 04, 2019 8:46 am Post subject: Re: OVM-14 question

I choose the Z13/8 instead of the Z12 because I have electrical dependent fuel and ignition. The Z13 seemed closest to my configuration using the Ford regulator rather than the B&C regulator.



The design concept is based on the article listed below. I wanted to have continuous flight with least amount of pilot intervention.



From "Electrical System Reliabilityâ€ 04/00

Adding an Aux alternator with auto switching



In normal flight both alternators are ON but the Aux alternator goes to sleep because it's regulator thinks the bus voltage is too high. If the main alt fails to support the ships loads, the bus voltage sags waking up the Aux Alt.



Reason I have circuit breakers on some items is because with a momentary switch, I can short to ground items to lighten load, which will trip the breakers reducing loads. Then if appropriate I can return function to selected items as the situation permits, By resetting the individual CB.

Cost fuse vs CB is not an issue as I have the CB already. Iâ€™m also using circuit breaker switches for some items and fuse for some other items.



My main question is how to get over voltage protection to work individually for each alternator. It would seem that if one alternator went high it would trip both field breakers. I think I need to monitor each output before it guts to the buss. However I could just let it trip both field breakers and the reset on. if it trips again reset the other. but that requires more pilot intervention. 

Any reason a low voltage warning light canâ€™t be installed with a resistor of of the terminal â€œIâ€ of the ford regulator? I think that is what ford does.



 

  	  Quote: 	
		  I'm doing 2 electrical energized field alternators (small frame 53A), one adjustable regulator,ï¿½  one non adjustable regulator, 2 OVM-14 modules, one battery off the Z13/8 dwg. 	


  If you have two, hefty alternators then

  Z12 is the better option.



 

  	  Quote: 	
		  I have two 5 amp Klixon circuit breakers for the fields. 	


  Okay



 

  	  Quote: 	
		  My question is about the OVM-14. If both alternators were in output mode due to low voltage then one went into over voltage, how do I get the OVM-14s to only trip the circuit for the one that is over voltage? It seems like both field circuits would trip the CB. 	


  You don't run both alternators at the same time.

  Run only the main alternator until you get a

  low volts warning then turn main alternator

  OFF, aux alternator ON>



  	  Quote: 	
		  Second question is about eBus.



 I have Circuit breakers for many things. Instead of a second bus, I was thinking of a momentary switch connected to the load side of all things that could be shut off in battery saving mode. Pressing the switch would trip the breakers for unnecessary items which could be individually turned back on if required. would a switch be adequate or should a 704-1 relay be used to handle the shorting load. 	


  I'm curious as to why Z12 is un-attractive as-published?

  What shortcomings in Z12 beg rectification?



  Also, aside from crow-bar field breakers, why

  not fuse blocks? Breakers take up space, add

  a lot of fabrication/installation labor, don't

  work any better than a fuse. 99.9% of all breakers

  installed at the factory go to the scrap yard

  never having been required to keep a wire from

  smoking. Why so much investment in a feature

  that adds nothing to the utility/reliability

  of your airplane?



 

 

   Bob . . .[/quote]

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Dec 05, 2019 8:04 am Post subject: OVM-14 question

At 10:47 AM 12/4/2019, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "jdpnm" <jdp3322(at)gmail.com>



 I choose the Z13/8 instead of the Z12 because I have electrical dependent fuel and ignition. The Z13 seemed closest to my configuration using the Ford regulator rather than the B&C regulator. 	


   ??? Z13 vs. Z12 has nothing to do with

   the style of regulator or electrical

   dependency of engine.



   Z-13 is specifically designed to MINIMIZE

   endurance loads on a TINY alternator . . .

   like the SD8. 



 

  	  Quote: 	
		  The design concept is based on the article listed below. I wanted to have continuous flight with least amount of pilot intervention.



 >From "Electrical System Reliabilityâ€ 04/00

 Adding an Aux alternator with auto switching



 In normal flight both alternators are ON but the Aux alternator goes to sleep because it's regulator thinks the bus voltage is too high. If the main alt fails to support the ships loads, the bus voltage sags waking up the Aux Alt. 	


   This narrative does not describe Z-13, it's

   talking about Z-12 with a second alternator

   driven by an SB-1 regulator (with autoswitch

   features). Z-12 is also just fine using an

   LR3 (or any other regulator). It just means

   you have to flip a couple of switches when

   the low-volts warning comes on.



 

  	  Quote: 	
		  Reason I have circuit breakers on some items is because with a momentary switch, I can short to ground items to lighten load, which will trip the breakers reducing loads. Then if appropriate I can return function to selected items as the situation permits, By resetting the individual CB.

 Cost fuse vs CB is not an issue as I have the CB already. Iâ€™m also using circuit breaker switches for some items and fuse for some other items. 	


   Breaker-switches have a poor track record

   in airplanes. They cost Beech a bucket-load

   of money when the proved less-than-robust in

   about 15 production-years of Bonanzas and Barons.



 



  	  Quote: 	
		  My main question is how to get over voltage protection to work individually for each alternator. It would seem that if one alternator went high it would trip both field breakers. I think I need to monitor each output before it guts to the buss. However I could just let it trip both field breakers and the reset on. if it trips again reset the other. but that requires more pilot intervention. 	


   Your worries about 'pilot intervention' are

   mystifying. One presumes that pilots do things

   based on knowledge, experience and planning.

   Actions needed to bring a standby alternator on

   line are trivial and NOT and emergency. When

   the low volts light comes on, your properly

   maintained battery will shoulder the loads while

   you finish your cup of coffee and turn off the

   MP3 player.



  	  Quote: 	
		  Any reason a low voltage warning light canâ€™t be installed with a resistor of of the terminal â€œIâ€ of the ford regulator? I think that is what ford does.



  	


   The FORD regulator warning light pin is 

   next to useless in airplanes. You need one and

   only one low volts warning light on the main

   bus. If you have an LR3 regulator on your main

   alternator, that light is built in. Recommend

   you use Z12 and I would discourage the use

   of breaker-switches.



   Any idea of fiddling with breakers in flight

   for load shedding sorta admits that you

   don't have a plan-B for abnormal operations.

   Z-12 with two FAT alternators say's you'll

   never need to do load shedding except for battery-

   only ops after having lost both alternators . . .

   an exceedingly unlikely condition.



   You're going to run out of gas or fly into

   convective weather before you loose two

   alternators on a single flight.



   Your engine loads should run off the

   battery bus.



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Dec 05, 2019 8:13 am Post subject: OVM-14 question

 	  Quote: 	
		  

 In normal flight both alternators are ON but the Aux alternator goes to sleep because it's regulator thinks the bus voltage is too high. If the main alt fails to support the ships loads, the bus voltage sags waking up the Aux Alt. 	


   P.S. If you're using B&C alternator controllers

   in Z-12, the ov control systems are 'selective

   trip' . . . when an ov condition is detected,

   each ov system looks to see if 'my alternator' has

   field voltage on it. If so, then the 'my regulator'

   is bad and I trip only 'my alternator'.



   If the field voltage is low or zero, the

   ov condition is generated by failure of the 'other

   regulator' it is expect to manage it's own

   shutdown operation.



   In an artfully designed multi-alternator system,

   it's easy to preclude tripping of both systems

   during an ov event.



   

 

   Bob . . .

racerjerry

Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY

Posted: Fri Dec 06, 2019 6:53 am Post subject: Re: OVM-14 question

 	  Quote: 	
		  Reason I have circuit breakers on some items is because with a momentary switch, I can short to ground items to lighten load, which will trip the breakers reducing loads. Then if appropriate I can return function to selected items as the situation permits, By resetting the individual CB.

	




PURPOSELY shorting out circuit breakers is generally not a good idea and will cause them to degrade.  Shorting, for rare over-voltage events is acceptable, but repeated high current events could cause a circuit breaker to malfunction; even possibly welding contacts closed.



A shorting switch is even more susceptible to arc damage and welding of contacts.



This reminds me of an Underwriter's Laboratory report describing a homeowner that "tested" his circuit breakers yearly using a screwdriver.  His house burned down as a direct result.

_________________
Jerry King

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Dec 06, 2019 9:04 am Post subject: OVM-14 question

 	  Quote: 	
		  

 PURPOSELY shorting out circuit breakers is generally not a good idea and will cause them to degrade.  Shorting, for rare over-voltage events is acceptable, but repeated high current events could cause a circuit breaker to malfunction; even possibly welding contacts closed. 	


   An urban technomyth completely unsupported by

   the physics and over a century of practice.



   A quality circuit breaker will find its

   way onto Qualified Products Lists (QPL) for

   government/military purchase by DEMONSTRATING

   anh ability to OPEN a faulted line supplied by

   a source current hundreds of times greater

   than the breaker's trip-rating. An exemplar

   table of qualifications for the Klixon 7274

   series breakers reads as follows:



 [img]cid:.0[/img]  

    A 5A breaker upstream of a crowbar OV protection

    system is qualified in systems capable of up to 800

    Amps of fault current. A typical ov trip current

    in a GA aircraft with crowbar OV management is

    on the order of 150 amps.



    Beech did crowbar OV management in a regulator I

    proposed for the single-engine, turbine prototype

    back about 1980. Of ALL the contemporary OV management

    systems on hand at the time, my prototype was the only

    one to manage a series of 50 OV events at the rate

    of one event every two minutes. After the test, the

    'abused' breaker still tested to design specs.



  	  Quote: 	
		  A shorting switch is even more susceptible to arc damage and welding of contacts. 	


   Do you mean a switch that closes a fault against

   a high current source source, or a switch used to open a 

   a high current condition?



   Contacts used to 'break' a faulted circuit, such

   as those used in a breaker, may indeed suffer arc

   damage if used to open a condition beyond the device's

   ratings (see Endurance and Interrupt ratings above).

   The crowbar OVM system that flies now in thousands

   of OBAM and TC aircraft were designed and tested to

   stay will within those limits. 



  	  Quote: 	
		  This reminds me of an Underwriter's Laboratory report describing a homeowner that "tested" his circuit breakers yearly using a screwdriver.  His house burned down as a direct result. 	


   I've heard several such stories over the years . . . all

   of which argue with contemporary design and qualification

   practices for modern breakers, switches and relays.



   I'd need to see the published failure analysis on

   this . . . sounds like an urban myth

   to me.



 

   Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Dec 06, 2019 9:12 am Post subject: OVM-14 question

Graybeards here on the List will recall some

   animated discussions about 14 years ago on the

   topic of 'abused breakers' in crowbar ov

   protection systems.



   Here's a white paper I generated as a contribution

   to those discussions:



  http://www.aeroelectric.com/articles/Crowbar_OV_Protection/DC_Power_System_Dynamics_C.pdf 



 



 

   Bob . . .

jdpnm

Joined: 26 Nov 2019
Posts: 6

Posted: Fri Dec 06, 2019 10:39 am Post subject: Re: OVM-14 question

thanks Bob.

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Fri Dec 06, 2019 12:35 pm Post subject: Re: OVM-14 question

 	  nuckolls.bob(at)aeroelect wrote: 	
		  At 10:47 AM 12/4/2019, you wrote:



  	


   ... You need one and

   only one low volts warning light on the main

   bus. If you have an LR3 regulator on your main

   alternator, that light is built in. 



 

   Bob . . .[/quote]



At the time of my installation, I thought that alternator 1 needed LVW through the LR3 reg.

Didn't think that the LR3 was monitoring the main bus so installed AEC 9005 LVW for Alt 2/Ford reg.

Now I have redundant LVW

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Dec 07, 2019 5:33 am Post subject: OVM-14 question

 	  Quote: 	
		  

 At the time of my installation, I thought that alternator 1 needed LVW through the LR3 reg.

 Didn't think that the LR3 was monitoring the main bus so installed AEC 9005 LVW for Alt 2/Ford reg.

 Now I have redundant LVW [Embarassed] 	


   Better to have more than you need than

   not enough!



   Many digital electro-whizzies include

   bus monitoring, display and sometimes

   a warning feature. It's not uncommon

   to have multiple, accurate bus voltage

   displays on the panel.



   But if one seeks the most informative

   'watch dog' for the ship's electrical

   system (or any other vehicle), the simple

   LV warning light fills the bill. All

   other forms of instrumentation are okay

   but they're more useful as diagnostic

   tools than electrical system management

   in flight.



 

   Bob . . .

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