Today's Message Index:
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1. 07:51 AM - Re: GRT EIS Issues When Transmitting (jjshultz)
2. 11:33 AM - Re: ovm (skywagon185guy)
Message 1
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| Subject: | Re: GRT EIS Issues When Transmitting |
I had an identical issue with my GRT EIS and an older NARCO comm radio. I surmised
that the radio antenna cable was affecting the EIS EGT/CHT probe thermocouple
wires leading into the EIS. I installed about 8-10 ferrite beads over the
antenna cable and the EIS data wire bundle, and it helped reduce the effect.
However, the ultimate solution was to reroute the radio antenna wire completely
away from the EIS wires. This solved the problem completely.
Although it may not be convenient to separate the antenna cable and EIS wires,
I suggest that is the best approach here.
Jeff
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=489081#489081
Message 2
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Very good point... "creep vs. nearly instantly"..!
As you figured out, I was thinking creep and that is not the real world
action..
Thanks for the details....
On Thu, May 2, 2019 at 5:16 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 01:32 PM 5/2/2019, you wrote:
>
> Only an assumption, but, I would think that the ovm trip setting should b
e
> lower than 16.2 vdc.
> Maybe in the 15 volt range.
> It would be great if someone with battery experience details would chime
> in on how high the charge voltage rate can go before starting to "cook"
=C3=82
> our aviation type=C3=82 batteries.
>
>
> First of all, OV conditions are first of all rare.
> Second, they almost never present a 'creeping rise' in
> bus voltage. OV regulation failures tend to be
> gross over excitation events that cause an
> alternator to deliver a constant current
> (slightly higher than its nameplate rating)
> with no practical limit to the limit to
> the alternator's UNLOADED output.
>
> The key word is UNLOADED . . . there are
> ship's accessories on line . . . then there's
> a battery that will attempt to absorb what
> energy is left over between alternator ratings
> and ship's loads.
>
> Hence, the voltage doesn't 'creep', rather
> it will rise at some observable rate over
> a period of seconds to perhaps a couple of
> minutes. OV protection systems are generally
> designed to trip for any ov condition that
> exceeds 16.0 (32.0) volts for something
> on the order of 500 milliseconds
>
>
> *(The DO-160 stand off value for 20.0/40.0v is 1.0 second). * In the
> exceedingly rare case that your
> regulator decides to do the creepy thing,
> it will no doubt be so slow that you'll
> easily know that something is amiss from
> observation of ship's various voltage
> displays.
>
> So, Eric's selected calibration point for
> ov trip is consistent with legacy
> design goals and very conservative in
> light of DO-160 qualification protocols
> along with alternator/battery performance under
> demonstrated ov stress.
>
>
> Bob . . .
>
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