Do you have one of the above voltage
regulators that has ceased to be a regulator? If so, and you're the curious
type, you're sure to appreciate this outstanding piece of circuitry teardown and
analysis by Baron 58 owner Derek dB.
HERE to get
his PDF narrative.
Here is more voltage regulator schooling from
Derek as posted on Beech Talk
Your vintage Baron has two regulators-- one is in use and the other is a
backup. The one regulator in use simultaneously supplies the field current to
both alternators. The field current creates a magnetic field inside the
alternator which is used to generate output current. The higher the field
current, the stronger the magnetic field and the greater the output of the
alternator. The job of the voltage regulator is to adjust the field current so
the alternator output is at a constant voltage (nominally 28.25V). If more
output current is being consumed than is being generated, the voltage drops and
the regulator increases the field voltage to keep up with the demand. The same
happens in reverse-- if the alternator output current is more than is required
by the electrical system, the bus voltage increases, which causes the regulator
to decrease the field current.
The left and right alternator outputs get joined on a common bus bar under
the nose baggage compartment and this is where the voltage regulator senses the
bus voltage. This type of setup is not a true paralleling of the alternators but
is instead two separate half systems (a left and a right) tied together. The
most efficient half system will drive the bus voltage and the other half will
"be along for the ride".
If the half systems are perfectly matched, both alternators will have
identical field vs. output curves and will be outputting exactly the same
current at exactly the same voltage with exactly the same input field current
and the alternators will share the load equally. But if there is any
difference in either half system---for example, a higher resistance on one side
in the loop from the voltage regulator field, to the alternator, to the bus bar,
back to the regulator, or if one alternator is stronger than the other---then
one alternator will supply more of the load. This is the case with almost every
Baron in existence because things are rarely perfectly matched (one can spend a
lot of time getting it close). Because the currents in these loops are large
(tens of amps for the alternators and 3 or 4 amps for the field), milliohm
differences can result in large voltage changes.
Sometimes, as might be your case, the half system imbalance is so large that
one alternator dominates and supplies all of the required current and
effectively keeps the other alternator off, which the system senses as a failed
alternator (the alternator out light will stay off as long as there is voltage
at the aux pin of the alternator; when the alternator output is low or zero,
that aux voltage is also low or zero). When that dominant alternator can no
longer can keep up with the current demand, its voltage will start to drop,
which will cause the regulator to output more field current, which will in turn
cause the second alternator to start to output current and take up the load (the
added field current will have little effect on the previously dominant
alternator because that alternator is at, or is reaching, its limit). This could
be what is happening when you turn on your landing lights.
Since the regulator is common to both alternators (both fields are supplied
from a single regulator pin), the problem you describe with a single alternator
is not likely due to the regulator. I would start looking at every connection in
the common bus bar-->regulator-->field-->alternator-->common bus bar loop,
(ground connections, too). If everything there is clean, then the next step is
to look at your left alternator.
Below is an early Baron charging circuit
diagram - be sure to note the applicable SNs for it!. Check your Shop Manual for
your SN for your specific diagram:
Below is an image of the early Baron Delco
9000591 voltage regulator which is supplied in pairs for the early alternator
equipped Baron 55s. Also below you will see the Farm & Industrial applications
that this same voltage regulator used to serve back in the day. Proof once again
that Beech utilized common industrial hardware of the day in many areas of the
Early Bonanza Delco-Remy Generator Voltage Regulator
for an excellent primer on the operation of the early Delco-Remy Generator
HERE is a link to the Delco-Remy Regulator Service Bulletin from 1953.
HERE is a link to the Delco-Remy Regulator Service Bulletin from 1960.
HERE is a link to the Generator Service Bulletin from 1961
Still sick of 1950's generator and regulator technology
and brownouts in your airplane during night ops? Ready to pitch the whole
system? Consider the
Plane Power ER14-50 generator conversion kit for E-Series Bonanzas
HERE is a peek
at an older install manual for the Plane Power ER14-50 conversion kit.