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1. 08:13 AM - Re: Re: Alternator Voltage Creeping Up (Robert L. Nuckolls, III)
2. 05:55 PM - test (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Alternator Voltage Creeping Up |
At 09:52 AM 11/22/2023, you wrote:
>Bob, if you had to buy a regulator for an OBAM=C2
>aircraft with EFIS and EMS, and conventional
>lycoming engine, legacy alternator, what would it be?
Good question. I'm not a diligent observer
of the totality of offerings in the market.
There are no 'bad' or even 'poor' regulators
with respect to voltage. Building a
perfectly adequate regulator is a trivial
design task. The legacy, 4-terminal 'ford'
regulator has been manufactured by the box-car
load for many years and is perfectly fine.
The risk for this and regulators of similar
architecture is predicated on a shared
pathway for the regulator's voltage sense
line and alternator field current. When
this pathway is polluted with too many
manufactured joints, resistances due to
age can add up to a point where the regulator
will (1) artificially raise the bus voltage
by a few hundred millivolts and (2) ultimately
become unstable due to prime directives:
(a) maintain xx.x volts on bus and
(b) meet field current demands consistent with (a)
If the resistance in the sense/supply path
goes up, these requirements may begin to 'chase'
each other generating the rare but irritating
'galloping ammeter' effect . . . combined
with a constant flickering of panel lights.
Early Cessna single engine ships had over
a dozen manufactured joints in this pathway
setting up a potential risk for this effect.
I believe other aircraft have suffer similar
effects.
I've only designed one 3-terminal regulator per
specs supplied by the customer . . . all
subsequent designs featured at least a
positive voltage sense; sometimes both positive
and negative sense paths. This provided for
much improved performance over the lifetime
of the regulator.
The only regulators I'm aware of that feature
a separate sense path is the B&C LR/LS series
devices. I designed the first LR series circa
1985 (Voyager carried two newly minted LR-1's).
From the get-go, B&C decided that any such
product offered would be an ALTERNATOR CONTROLLER
consisting of a remote sense regulator, built
in over voltage management and active notification
of low voltage. I used to pitch the LR series
regulators over the counter at OSH by stating
the product was THREE devices at $75
each . . . making the $225 price a bargain.
There are many examples of separate sense
architecture out there. Ebay has many
by Lamar, ElectroDelta and others. But these
are all used, PMA devices with price tags to
match. None will include active notification
of low volts . . . only a few will have
ov management.
Therefore, burdened with ignorance of any
similarly configured products, the B&C LR3
would be my first suggestion. If one were
strongly motivated seek lower cost alternatives,
I'd go with a 'ford' 4-terminal regulator
teamed with a crowbar OVM and a low-volts
annunciator of some sort.
The 'ford' regulator will be just fine if
you minimize joints in the field supply line
and fabricate with PIDG quality terminations.
Bob . . .
////
(o o)
===========o00o=(_)=o00o=======
=
< Go ahead, make my day . . . >
< show me where I'm wrong. >
========================
========
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
Message 2
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Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
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