RE: 3 phase car alternators

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Leigh Copp" <Leigh.Copp@xxxxxxxxxxx>

Jim,

As I understand things, an automotive alternator (like the 990 MW units
at nearby Darlington Nuclear) does not have a rotor per se, but a
rotating
-field- winding, that is excited with DC through slip rings (as opposed
to brushes and a commutator). The magnitude of the DC current through
the field determines the magnitude and angle of the AC voltage that is
generated.

Are you thinking of a generator, which has a commutator (and is
basically a DC machine)?

The alternator can be rewound to change the output frequency vs. machine
speed characteristic (or "k"). There are some efficiency tradeoffs as
well however.

Leigh


-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: October 17, 2006 2:38 PM
To: tesla@xxxxxxxxxx
Subject: RE: 3 phase car alternators

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 07:09 AM 10/17/2006, you wrote:
>Original poster: "Terry Oxandale" <Toxandale@xxxxxxx>
>
>Could the poles be rewired into fewer parallel circuits (and thereby
>decreasing the number of poles) increasing the current output and
>decreasing the frequency. I've never looked into an alternator, and
>would guess this is a major undertaking.

The bigger problem would be the rotor, which has a fixed number of
poles.

I think you're right.. major undertaking.