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I wanted overvoltage protection in my Alternator so I installed an additional Master Relay in the Alt B+ circuit. That allowed me to jump B+ to the field terminal on my internal regulator, simplifying the wiring of the charging system. If my Alt Switch is off, the Alternator is totally isolated from the rest of the electrical system regardless of the position of the Master Switch.
Has several advantages ... Jim S.
Ian Beadle wrote:
----- Original Message -----
*From:* Al Gietzen <mailto:ALVentures@cox.net>
*To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
*Sent:* Saturday, May 14, 2005 11:29 PM
*Subject:* [FlyRotary] Re: Hot Alternator???
For those of you in the know, is it normal for an alternator
to seep current and get warm when the field coil is powered
up? Is this something I need to fix? If so, should I cancel my
trip? I think it has probably been going on for a long time but...
The field current is controlled by the regulator, which is
usually internal. The regulator will only allow field current
if the armature is spinning and bat. below about 14 volts. A
small amount of current is allowed at start up via the little
red light to give initial voltage.
In short get the regulator checked.
Ian Beadle.
Ian;
With the alternator not running, the battery voltage will
always be below 14 volts; even with the charger on, so the
field current will flow. Dave has modified the internal
connection the same way I did to provide external feed to the
field windings. This does not run through the warning light.
So with battery voltage to the field, alternator not running;
I estimate it will draw 2-3 amps. Plenty to make the
alternator pretty warm after awhile.
Also, I don’t think tripping a 5 amp breaker in field circuit
indicates anything wrong. With the battery a bit low and a,
say, 60A alternator spinning, the field could draw 5 amps. I
use a 7.5A breaker on my field current circuit.
Al
There should be a relay connected to D on the alternator, this
ensures that the field is only powered when the alternator is
spinning.
Ian
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