tcone1

tcone1

Well Known Member
Hello People,

I am sad to report that the impossible (according to some) has happened. My internally regulated alternator failed HIGH. I feel very lucky that the only things that the voltage transient killed were all the Van's engine and fuel gauges...all 10 of them. Oh, and the landing and taxi lights. Everything else survived. Total time in service was 70 hours.

I've had the alternator rebuilt...Van's is backordered...because they won't be selling them any longer.

What are people doing in terms of overvoltage protection? I would like to keep the modification to a minimum, so an inline overvoltage relay would be great, but my circuit design skills perished...all knowledge is perishable when left in my little pea sized brain for years and years. Is there a commercially available solution?

Thanks,

Tim

No animals were harmed, but yes, electrolytic capacitors were harmed during the production of this film...they blew their little wads (literally). Some of them blew with enough energy to dent the back side of the gauge faces.
 
OVP

If your IR alternator doesn't turn off when you remove the activation voltage, then the only way to protect from an OV situation is to put a contactor on the B lead, and use a commercially available OV module (from B&C or Perihelion) to control that contactor. See any of Bob Nuckolls diagrams for a schematic, but basically the ALT position of your master switch powers the OVP device which closes the B lead contactor and provides the activation voltage to the IR.

That architecture has caused problems with some IR alternators (particularly Van's) when the B lead contactor is opened while the alternator is under load (by turning off the master switch before shutting down the engine). So the operational solution is to turn off the master ONLY after stopping the engine. Bob N is working on a device to resolve this problem, but it's not available yet.
 
By far, the easiest, most elegant solution to your problem is to simply use a plane-power alternator. Internally regulated with internal OV protection. All the technical details are on their site.

http://www.plane-power.com/

Van's sells it here.

I have this unit on my RV and am very happy with it so far.
 
Avionics

Gil,

Yes the avionics master was on. All of the radios are fine, the efis and map are great...
 
Plane Power is the only way to go IMHO. The voltage protection is worth it's weight in gold, literally.

You were lucky to get on the ground without a fire.
 
OV protection

Do you mean that the B&C OV protection device is OK with Vans IR alternator if I simply avoid turning alt "off" before stopping the engine? That would be great for me if true - already have Vans alternator (mounted, with prop and belt) and the OV module from B&C. Thanks for any input. Bill
 
Bill Dicus said:
Do you mean that the B&C OV protection device is OK with Vans IR alternator if I simply avoid turning alt "off" before stopping the engine? That would be great for me if true - already have Vans alternator (mounted, with prop and belt) and the OV module from B&C. Thanks for any input. Bill
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That's my (limited) understanding, Bill. The only problem is that more than once in the past have I accidently turned off the master in flight when my head was somewhere else. I'm concerned that a little slip like that could have disastrous consequences. It shouldn't. Others with more knowledge should speak to this though.
 
Avionics

tcone1 said:
Gil,

Yes the avionics master was on. All of the radios are fine, the efis and map are great...
Click to expand...

That's really interesting given previous discussions on the usefulness of an Avionics Master switch...;)

The overvoltage was severe enough to blow light bulbs, but the avionics all survived.

There really must be some good to that DO-160 testing after all....:D

..and you have finalized my plan for no Avionics Master - heck - this modern radio stuff is good...:cool:

gil A

PS - I don't think Vans claims DO-160 compliance for his cheap engine gauges...:)
 
OV protection

Steve: thanks for your reply. Hope it doesn't happen to me in the early hours. If so will probably buy Plane Power or B&C. Bill
 
max voltage

Marc,

I do not know what the max was. I would guess near 100V, but that would be a guess.
 
B&C OV has 3 (heavy parts), Plane Power, Questions?

AMURRAY said:
Get an OVM-14 from B&C. Only 35 bucks. It can be used with your Vans alternator.
http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?26X358218
The only problem is, it is possible to smoke your voltage regulator if you remove power from it when it is running. But regulators are a lot cheaper than instruments and avionics. Aaron
Click to expand...
Yes but that works with CB and a large (master relay) sized solenoid. Although they are not expensive it adds another $50 + $35. Also it adds a pound or so of weight. A Plane power unit would be better. By the time you by all the add on jury rig, you would be better off just getting the PP unit. Also this little gadget has been known to trip accidentally which will for sure fry a good alternator and fry it well.

tcone1 said:
Marc, I do not know what the max was. I would guess near 100V, but that would be a guess.
Click to expand...
Rebuilds are terrible. Sorry for you problem, but may be we can learn something from it.

100v is a nice round number folks have thrown around in theory, but how do we really know?

Documented OV reports of Van's "60 amp" alternator, are typ very mild, 16 - 18 volt range, in my research. Not saying your are wrong, but how do you know? To do a little "detective work" could you answer a few questions, please?

It would be interesting to test a bulb and see what it takes. That would/might determine the OV threshold.
(what kinds of bulbs burned out?)

Avionics (modern) tend to have OV tolerance up to 60 volts , some only 30 volts, may be a little less. what kind of avionics do you have? (I am just curious, because apparently they are very robust. It would be good to know.)


Is 18 volts enough to burn out Van's gauges? I don't know; they're not very robust instruments are they.
(I would have guessed the amp meter & volt meter would tolerate OV, not 100v, but I'm not convinced it's that high.)

As far as over-voltage I would buy a Plane Power unit. The internally regulated units have additional OV protection.

Where you in the habit of turning on the alternator after start and off before shut down?
(This procedure usually kills the internal regulator, over time not instantaneously unless at high RPM/loads.)
 
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I just came in from the garage with a Nippondenso alternator I had been doing some tests on. I was looking for the proper way to get rid of alternator whine which gets picked up by radios. I thought I had marked on the side of the case what the KeS, volts/rad/sec, of it was but all that was on there is that it put out 6 cycles/rev times 3 phase. If you remember you used to be able to get a unit that connected to the alternator circuit to allow you to use your vehicle's alternator to power 115V series-wound saws and drills. On some you regulated the voltage by adjusting the engine's rpm, and on others you set the rpm high and it would regulate the output. I also have a B&C Specialties PM alternator I was making a buck-boost regulator for to enable some charging on low rpm. Somewhere I have the data on it, but if memory serves me, it seems it took about 1600 rpm to just get to 14V. Its voltage output would basically be something on the order of rpm X 14/1600.
 
George,

I'm all for learning...that's what this community (VAF) is all about for me.

100V was a stated guess. If you say you have documented reports then by all means go with those numbers. I guessed 100 based on my experience with the kits that allow you to generate 115vac from your car alternator. I'm also basing the guess on the size of electrolytic capacitor that popped it's canister hard enough to dent the back of the gauge face. I used to be an avionics tech, back in the days before aviation pentium driven nav/comms/gps. (Digital radar sucks, how can a tech hurt himself on that few watts, more importantly, how can you sterilize ground service personnel and knock birds from the sky with your radar if it's only got 50 watts?)

The landing and taxi lamps that fried were 55W H3 bulbs as supplied with the duckworks kits from a few years ago. I'll hook a new one up to my lab power supply and see just how much DC she'll take. If I get to 60VDC without failure, I'll switch over to my variac and see where she fails VAC.

The avionics are a Garmin SL40, Dynon D10A, Garmin GTX 327, Lowrance 2000C and an AFP-30. It doesn't surprise me in the least, that these all survived a brief voltage transient...am I going to conduct the same experiment on the stack that I'm going to subject the new landing light to????? Heck no.

I do not apply or remove field excitation while the alternator is turning...I only turn the alternator on or off prior to starting and after shutdown. Remember that I only de-energized the field in this instance due to an obvious malfunction...I was trying to stop a run away alternator before it made my battery look like that electrolytic cap. Frying the regulator was an expected possible consequence and was something I was willing to put up with to prevent an emergency from developing.

The lesson I learned is that just because something never happens (regulator failing high) doesn't mean you can design your system ignoring the possibility. As to how to fix my design flaw, sometimes a crowbar is the correct tool. If it's a one in a million shot that the regulator will fail high, dropping a crowbar across the output and killing the thing is fine. If I'm going to be putting new internally regulated alternators on every 70 hours or so, then yes a better mousetrap is on the way.
 
There is an entire chapter of the DO-160E specification devoted to just this problem, and well designed avionics and other components can handle overvoltage transients. Unfortunately, less expensive instruments tend to skip this and will fail.

We designed our LED landing lights to handle transients like this. They will crowbar the transient at 40V which will most likely trip the breaker that they are connected to. It's a good idea to check the equipment that you buy to see if they comply with the DO-160E requirements, and if doubt, you should inquire with the manufacturer to see if they designed and tested to this requirement...

Dean Wilkinson
AeroLEDs LLC
www.aeroleds.com
 
Learning is fun

tcone1 said:
George,

I'm all for learning...that's what this community (VAF) is all about for me.
Click to expand...
Timothy Cone, thanks a million. I appreciate it a lot. I just have a bug to learn and understand why? I appreciate your reply a lot. I totally agree, but I hate for you to waste another bulb. Its a H3 55 watt, so I might try it my self. I don't have a variable power supply however, but I could rig something up. I-VR's should no be failing so much. You have the VR? If you want to send it to me I'll pay for the shipping. (just pvt message me or email me and I'll send you my address). I would like to have it. What I'll do with it is forward it to a company that makes replacement VR's. They have X-ray and can dissect it to determine the reason for the failure. I have talked to them about OV issues. They would like to see what the issue is, even if its not their product. As I have written before, not all after market parts are the same. I suspect Van had a bad vendor for a while. There are many companies that make electrical parts for the alternator rebuild industry. Some replacement VR's cost $5 and others cost $45? Great reply thanks again.
 
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V Reg is gone

George,

I didn't think to have the rebuilder save the bad parts for me...some ntsb investigator I'd make.

Allbee,

Unfortunately, fuses don't protect against over voltage, they protect against over load. The crowbar I referred to was an electronic device that senses the over voltage condition and drops the alternator output to ground...causing an over load condition to trip the CB or blowing the fuse. I did not have a crowbar in my original installation.

Tim
 
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