Re: Production EVs

[XURQ03A@prodigy.com ( LEE A HART)]

Bill Dube' wrote:
> You can re-wind an existing AC motor to nearly any voltage you like,
> but you have to pay for the re-wind.

Paul Compton wrote:
> If want to operate an AC motor at full rated torque significantly above
> its base speed you've little option but to rewind it. The standard 20 hp
> motor used in the Motorola truck was rewound for 150 volt.

AC motors are quite easy to rewind. You don't have to change the rotor at all.
The stator windings don't move, so balance and centrifugal force issues don't matter.

Since all motors have at least 2 poles, they have 2 coils per phase. The
factory usually wires them in series (allows fewer connections and fewer
turns). But you can cut the series connection between coils, and wire them in
parallel for 1/2 voltage. Similarly, a 4-pole motor has 4 coils that can be
reconnected for 1/2 or 1/4 voltage.

If you need to rewind an AC motor, carefully make notes of how it is wired and
insulated. Cut off the old wire, carefully counting turns. Make a form with
the same shape and length as the old wires (basically just a rectangular block
of wood). Calculate the new number turns (same ratio as the voltage: If 100
turns = 240vac, then 50 turns = 120vac, etc.). Wind the wire loosely on the
form. Temporarily tape or bind it together with string.

Now remove it from the form, and feed it into the motor slots, a few wires at
a time (the slot isn't big enough to fit the whole coil into at once). Once
you've crowded it all in, wedge it in place with fish paper shims. The ends of
the coils will be a bit long, so they can be bent to get out of each other's
way. When you've got 'em all in, lock them in place with epoxy or transformer varnish.

Lee Hart                     If you would not be forgotten
4209 France Ave. N.          Soon as you are dead and rotten
Robbinsdale, MN 55422 USA    Either write things worth the reading
phone (612) 533-3226         Or do things worthy of the writing
e-mail XURQ03A@prodigy.com   (Ben Franklin, Poor Richard's Almanac)