Today's Message Index:
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1. 06:19 PM - Re: 30A PM alternator and Z101? (johnbright)
2. 06:32 PM - Re: flyback diode across fuel pump (johnbright)
Message 1
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| Subject: | Re: 30A PM alternator and Z101? |
nuckolls.bob(at)aeroelect wrote:
> At 09:14 PM 6/10/2022, you wrote:
>
> Not exactly a precision test instrument. Next time
> you talk to him, suggest that I can plot efficiency
> and performance curves with some degree of confidence
> along with quantification of the 'spike' theory.
>
> . . . suitable NDA provided . . . of course.
>
> Bob . . .
Hi Bob,
I have communicated by email and telephone with Bill Judge of Monkworkz.
I passed along your offer of doing performance testing and evaluation of the spike
that trips OV protection if the B lead is disconnected under load. At present
Bill plans to keep testing in house.
Present Monkworkz documentation shows the B lead connected downstream of the master
contactor. Perhaps Bill will come up with a recommended Z101 implementation.
I shared my brainstorm configurations from post 9 with him.
Bill has a customer who connected the B lead to the battery using a relay independent
of the master contactor and has hit the OV protection by opening the relay
under load. This does not happen with the B lead connected downstream of the
master contractor.
Per Bill:
Why does this happen? Well, there are inductors inside the regulator, you can't
instantaneously change the current in an inductor, the current has nowhere to
go and causes a spike. That spike gets mopped up by a massive (1.5kW) TVS diode
on the output but that doesn't kick in until the voltage goes over ~16 V, and
the OVP kicks in at 15.3 V.
The generator has nothing to do with the spike. The output of the generator is
rectified and sent through a voltage converter, the voltage converter is causing
the spike.
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
https://drive.google.com/folderview?id=1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=507803#507803
Message 2
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| Subject: | Re: flyback diode across fuel pump |
nuckolls.bob(at)aeroelect wrote:
> At 09:57 PM 8/25/2022, you wrote:
>
> >
> > Someone on VAF suggested putting a flyback suppression diode across fuel pump
leads like we do with contactor and relay solenoid coils. This was re an automotive
fuel pump like SDS/EFII/Airflow Performance/Walbro.
> >
> > What say Bob et Al?
>
> Did the author cite a noise problem which was
> mitigated by adding this component?
>
> I'm mystified by any assertion of added value.
> Rotary pumps powered by pm motors have no
> 'flyback' event. PutPut pumps like the
> Facet devices have electronically driven
> solenoids that 'cock' a compression spring.
> A cruise through the genealogy of exemplar
> patents for such pumps . . .
>
> https://tinyurl.com/2e6mmzyr (https://tinyurl.com/2e6mmzyr)
>
> . . . illustrates commonly applied
> technology for mitigating flyback
> energies in these devices that include
> resistors, diodes and capacitors as
> part of the designs dating back over
> 30 years.
>
> I'm curious as to the history of
> the thread.
>
>
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
Hi Bob,
The VAF thread started as local ground or forest of tabs for fuel pump ground?,
EFI fuel pump, and drifted at post 9 to someone recommending a diode across the
pump motor to protect the pump switch. I had never heard of this so I asked
here on AEL.
https://vansairforce.net/community/showpost.php?p=1629894&postcount=9
--------
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
https://drive.google.com/folderview?id=1u6GeZo6pmBWsKykLNVQMvu4o1VEVyP4K
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=507804#507804
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