sttwig
Joined: 26 Aug 2007
Posts: 31
Location: Yakima, WA
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 Posted: Thu Sep 18, 2014 9:32 am Post subject: alternator knocked off line when strobes turned on |
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Joe,
Thank you for your input.
About all I know about the strobes is that they are old Whelans. The alternator kicks out immediately, within 2 or 3 SECONDS upon switching on the strobes. I have seen no failure in the strobes as they continue to operate normally, on battery power, after the alternator is kicked off line. Per another suggestion, I am going to look for power supplies for the strobe system in the wings in addition to the one next to the battery which may be just for the tail.
Steve
On 9/17/2014 8:42 PM, Joe Motis wrote:
| Quote: | Hi Steve, I am assuming that your strobes are capacitive discharge, what if some of the capacitance is going to ground after it warms up 2 to 3 minutes as per your data.
Is a partial or intermittent failure in the strobe power supply capable of sending high voltage pulses back into the 12 volt side of the system?
Bob?
On Wed, Sep 17, 2014 at 2:53 PM, Steve Sundquist <sttwig(at)gmail.com (sttwig(at)gmail.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: Steve Sundquist <sttwig(at)gmail.com (sttwig(at)gmail.com)>
I have done the suggested testing. The bus voltage at 1000 rpm settles in around 14.24 volts although I did see it as high as 14.4 volts at one point. The bus voltage is virtually the same at 2000 rpm. When I load up the system to 45 plus amps at 2000 rpm, the bus voltage drops to about 13.1 volts. When I dump the load all at once the system does not trip. The battery is an Odyssey PC680 about three years old. The voltage regulator is not adjustable, but it appears that is not the problem.
Thank you
Steve
Sent from my iPad
> On Sep 17, 2014, at 5:52 AM, "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
>
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
>
> At 22:54 2014-09-16, you wrote:
>> --> AeroElectric-List message posted by: Steve Sundquist <sttwig(at)gmail.com (sttwig(at)gmail.com)>
>>
>> Thank you for your response.
>> This is a new condition. The OV protection relay is part of the InterAv system, part no. 635-62448. There is no voltmeter in the system so I don't know what the normal buss voltage is. The only instrumentation in the system is the ammeter on the alternator output. I will load up the system and turn it all off at once after I reinstall the alternator. I removed it for testing at a local shop.
>
> Sorry you went to the trouble before troubleshooting
> to find out what device needed to be repaired/replaced.
>
> It's unlikely to be the alternator.
>
> You need to KNOW the regulation set-point for the
> system. Get a digital voltmeter and check voltage at
> the bus at 1000 rpm and minimal electrical load, 2000
> rpm and min load, then 2000 rpm with max load. While
> at 2000 rpm, see if you can cause the system to trip
> with the load-dump experiment I suggested earlier.
>
> The symptoms you've described thus far strongly suggest
> a skitterish ov protection system being irritated by
> either an elevated bus voltage -or- internal cauese.
> The most likely is elevated bus voltage. If your
> regulator is adjustable, set the bus to 14.2 volts.
>
> What kind of battery and how old?
>
> This is a good discussion to be sharing with the rest
> of the List membership. Getting the tools out to remove
> a piece of hardware is best reserved until you KNOW which
> piece needs to be removed. Fortunately, there are relatively
> easy techniques for deducing which piece that is.
>
>
>
> Bob . . .
>
>
>
>
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