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nuckolls.bob(at)aeroelect
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 Posted: Thu May 14, 2009 6:56 pm Post subject: Alternator excitation - suggested wiring? |
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| Quote: | My alternator has three connections, one for field, one for 12v
excitation, and the B lead. I have the B&C LR3C regulator, overall
electrical is a Z19. The alternator was built by a local high
performance shop, after talking through the needs of my aircraft.
Good bearings and grease, precise tolerances, etc. All those things
Bob talks about in his book. The instructions that came with it say:
"Alternator has isolated field wires. Either one can be the IGNITION
ON 12 volt supply wire. The other to the FIELD CONNECTION on the
regulator. The regulator case must be grounded. "
Okay, the connections described are for
a "pull-down" regulator . . . typical of
the built in regulators. The LR3 is
a "pull-up" style device. This means
that one of your free field leads goes
to GROUND instead of 12v excitation. The
other field terminal connect to the FIELD
lead of the LR3.
So what I was planning to do is run a small wire from the B lead on
the alternator to one of the alternator's connections, making it the
IGNITION ON connection.
No, that's what you do for the "pull down"
regulator architecture. Take one field lead
to ground.
Then connect the other tab to the Field connection on the regulator.
Yes.
That way when I turn on the Master Switch to middle position (batt)
it sends 12 volts to the IGNITION ON connection. The hope being
that is supplies the alternator with that 12 volt IGNITION ON voltage.
Technically, once modified for legacy
functionality as an externally regulated
alternator, there is no more "IGN" terminal.
Just F1, F2, B and GND (case).
I already know that turning the Master Switch to BATT position (or
Alt) sends power all the way to the B lead.
Yes . . . through your b-lead protection
device. ANL, MANL or other fat fuse.
What I am not sure about is: do I need to keep that
excitation/Ignition on voltage running all the time the engine is
running (would it hurt anything if I did)? Or should it be shut off
after the engine is started and alternator is producing power?
If wired per Z-19 (or any other Z-figure, the
DC PWR MASTER switch has control over the
alternator.
My Master Switch is exactly as in the Z19, so it controls the on/off
of the regulator already.
Then it controls the alternator too. If the
regulator is unpowered, the altenrator is OFF.
It is this question of excitation that I am unclear about. Lots of
articles talked about the need for an ignition on light as a
mandatory component in making some alternators actually operate.
This is only for some (in fact a few) alternators
with built in regulators. This feature no longer
applies to your situation.
|
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Thu May 14, 2009 7:27 pm Post subject: Alternator excitation - suggested wiring? |
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My alternator has three connections, one for
field, one for 12v excitation, and the B lead.
I have the B&C LR3C regulator, overall electrical
is a Z19. The alternator was built by a local
high performance shop, after talking through the
needs of my aircraft. Good bearings and grease,
precise tolerances, etc. All those things Bob talks
about in his book. The instructions that came with it say:
"Alternator has isolated field wires. Either one
can be the IGNITION ON 12 volt supply wire. The other
to the FIELD CONNECTION on the regulator. The regulator
case must be grounded. "
Okay, the connections described are for
a "pull-down" regulator . . . typical of
the built in regulators. The LR3 is
a "pull-up" style device. This means
that one of your free field leads goes
to GROUND instead of 12v excitation. The
other field terminal connect to the FIELD
lead of the LR3.
So what I was planning to do is run a small wire
from the B lead on the alternator to one of the
alternator's connections, making it the IGNITION ON
connection.
No, that's what you do for the "pull down"
regulator architecture. Take one field lead
to ground.
Then connect the other tab to the Field connection on
the regulator.
Yes.
That way when I turn on the Master Switch to middle position
(batt) it sends 12 volts to the IGNITION ON connection.
No, just the B-lead terminal. The field supply
delivered through the regulator is still cold until
you take the DC PWR MASTER all the way up.
The hope being that is supplies the alternator with that
12 volt IGNITION ON voltage.
Technically, once modified for legacy
functionality as an externally regulated
alternator, there is no more "IGN" terminal.
Just F1, F2, B and GND (case).
I already know that turning the Master Switch to
BATT position (or Alt) sends power all the way to the B lead.
Yes . . . through your b-lead protection
device. ANL, MANL or other fat fuse.
What I am not sure about is: do I need to keep that excitation
/Ignition on voltage running all the time the engine is running
(would it hurt anything if I did)? Or should it be shut off after
the engine is started and alternator is producing power?
If wired per Z-19 (or any other Z-figure, the
DC PWR MASTER switch has control over the
alternator. Start BATT only, once engine is
running, bring alternator on line. Reverse
process at ramp idle before parking the airplane.
My Master Switch is exactly as in the Z19, so it controls
the on/off of the regulator already.
Then it controls the alternator too. If the
regulator is unpowered, the alternator is OFF.
It is this question of excitation that I am unclear about. Lots
of articles talked about the need for an ignition on light as
a mandatory component in making some alternators actually operate.
This is only for some (in fact very few) alternators
with built in regulators. This feature no longer
applies to your situation.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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mikefapex
Joined: 05 Jul 2007
Posts: 70
Location: Colorado
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| Posted: Sat May 16, 2009 2:24 pm Post subject: Re: Alternator excitation - suggested wiring? |
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Bob,
I wanted to update you. After getting a new alternator plug that has the connections I needed, I experimented and rewired the field and ground leads per your suggestions.
WhaLa, alternator started outputting about 15 volts. Too high, but a few turns of the LR3C regulator screw has it now outputing 14.2 volts. And if I move the Master Switch to BATT position the alternator stops producing voltage. Like Hannibal Smith always said: 'I love it when a plan comes together'.
I have a Z19 system, and here are the measured voltages from various instruments/locations:
Digital meter directly on the main battery: 14.23 v
Digital meter on the Z23 field wire to cockpit: 1.90 v
Digital panel Voltmeter on Ebus: 14.10 v
EM2 engine monitor connected to main bus: 14.44 v
Is that Z23/field voltage what you might expect?
Thanks again,
Mike
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sun May 17, 2009 6:05 pm Post subject: Alternator excitation - suggested wiring? |
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Bob,
I wanted to update you. After getting a new alternator plug that has
the connections I needed, I experimented and rewired the field and
ground leads per your suggestions.
WhaLa, alternator started outputting about 15 volts. Too high, but a
few turns of the LR3C regulator screw has it now outputing 14.2
volts. And if I move the Master Switch to BATT position the
alternator stops producing voltage. Like Hannibal Smith always said:
'I love it when a plan comes together'.
I have a Z19 system, and here are the measured voltages from various
instruments/locations:
Digital meter directly on the main battery: 14.23 v
Digital meter on the Z23 field wire to cockpit: 1.90 v
Digital panel Voltmeter on Ebus: 14.10 v
EM2 engine monitor connected to main bus: 14.44 v
Is that Z23/field voltage what you might expect?
Yes, depending on RPM and system loads, the
field excitation to the alternator can be quite
low. At low RPM and high loads, this reading
will climb until it reaches at or slightly
below bus voltage . . . this is were the alternator
is maxed out. A very low reading says the alternator
is carrying present loads without breaking a
sweat.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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