Today's Message Index:
----------------------
1. 09:01 AM - Re: Rotax/Ducati alternator webpage (Robert L. Nuckolls, III)
2. 01:24 PM - Re: Re: Crossover Light on (skywagon185guy .)
3. 05:58 PM - Re: DC clamp meter (blues750)
4. 08:20 PM - Re: Re: DC clamp meter (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Rotax/Ducati alternator webpage |
At 05:37 PM 5/10/2020, you wrote:
>Le 10/05/2020 =C3 19:57, Charlie England a =C3=A9crit=C2 :
>>
>>NB:=C2 The frequency is used to determine the rotation speed.
>>200 Hz with 5 pairs of poles corresponds to 40 rpm, i.e. 2400 rpm.
>>Not really sure what's going on there, with 40 rpm and 2400 rpm.
>>
>>And of course, we barbarians always struggle
>>with temperature measured in C. Not because it
>>isn't better, but because we weren't properly schooled. :-)
>>
>>Otherwise, it was very readable using the Google Translate version.
>
>
>Charlie and all,
>
>Thank you to those who took the time.
>
>So Google might be a valuable source after all.
>
>It is true that we're so picky on style and grammar in my language...
>
>I'll have a try at it, do not hesitate to
>propose a correction if something looks awkward or inaccurate.
Gilles,
This is an extra-ordinary paper that defines
the physics that govern the operation of that particular
alternator . . . and offers a benchmark for how all
pm alternators should be explored and documented.
I'd be pleased to add your work product to
the library on aeroelectric.com
Bob . . .
Message 2
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| Subject: | Re: Crossover Light on |
Good catch by both of you electro-types....
Nice easy solution too....
On Sun, May 10, 2020 at 6:45 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
>
> So..,, since then, I finished wiring in radios etc, and now the cross over
> light is on when I turn on only the Aux master (I have installed the Z-14
> dual batt dual alternator). (It's in a Long Ez). Everything seems to work
> correctly, starter, crossover, etc. when I turn on the main master I don't
> get the light, when I turn on both masters, I don't get the light, it's
> just when I turn on only the Aux master.
>
>
> Boy . . . that's a lot of harxware to be
> carrying around in an Ez . . .
>
> You have discovered a 'bug' in the architecture.
> A 'sneak path' exists from the hot aux bus thru
> the cross-over contactor coil then through
> the CROSSOVER WARN light to the DEAD main bus
> as a 'ground'.
>
> See https://tinyurl.com/ydg99c5w
>
> You can fix this by adding a diode (any handy
> size will do) in series with the CROSSOVER WARN
> light as shown in the sketch.
>
> You can install it in the lead wire to the
> annunciator fixture. See
>
> https://tinyurl.com/kyc6tq6
>
> for the technique.
>
> Thanks for the heads-up! I'll update
> Z14 to add this fix.
>
>
> Bob . . .
>
Message 3
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| Subject: | Re: DC clamp meter |
Bob, finally able to do the calculation on how you get a 1 OHM equivalent resistor
out of the four resistors rated at 4 ohms in parallel. What a blast from the
past! I'll take your word on the Power rating being suitable!! Thank you so
much for the help and interest. I can't wait to get some data!
Dave (most appreciative novice experimentalist)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=496289#496289
Message 4
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| Subject: | Re: DC clamp meter |
At 07:54 PM 5/11/2020, you wrote:
>
>Bob, finally able to do the calculation on how you get a 1 OHM
>equivalent resistor out of the four resistors rated at 4 ohms in
>parallel. What a blast from the past! I'll take your word on the
>Power rating being suitable!! Thank you so much for the help and
>interest. I can't wait to get some data!
Yup . ..
1
RT = ===================================
1 1 1 1
____ _____ _____ ______
R1 R2 R3 Rx
Rtotal equals the reciprocal of the SUM
of reciprocals of all resistors in the
array . . . no matter how many resistors.
It just so happened that your target current
worked out close to a 1-ohm load . . . so
the array of 4 x 4 ohms works nicely.
The total wattaged needed is much less than
to total ratings of thsoe four resistors.
They're offered as 100W devices . . . but
in practice, they're closer to 50W when
adequately heat-sinked. So the sum total
of the 4 is comfortably good for 200W.
You only need 13A x 13v is 169W.
This bucket-o-resistors technique is
very versatile. For example, a couple
years ago I crafted a portable, 750
watt, variable load bank for the purpose
of airborne cooling tests on alternators.
An array of 21 resistors not unlike the
ones I suggested plus a handful of components
and a fan made for a device that would
offer loads from 0 to approx 50A fan
cooled.
I've used this technique to craft load banks
up to 2800 watts (28v, 100A) . . . with
a lot more resistors and a bigger fan . . .
but knob-adjusted at the control panel.
Bob . . .
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