Re: rotary gaps+- problems

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "bob golding by way of Terry Fritz <twftesla-at-uswest-dot-net>" <yubba-at-clara-dot-net>

Hi All,
    After talking to a friend who knows more about single phase motors than
me I decided that it
is a normal series wound motor with an extra winding to help starting
torque. He reckoned this
extra winding was unnecessary and could be disregarded. I carefully wound
up the variac with
just two wires from the motor connected. One wire goes to the field winding
on one side. The
other lead goes to the armature. The other side of the armature goes to the
other field winding.
I think this is the conventional series winding arrangement of most
universal ac brush motors.
Anyway IT WORKS :-)). It is only drawing the design current and spins the
rotor up to 5500RPM
with no trouble at all. Now all I have to do is stop it shaking the house
apart. A mere
mechanical problem.

Very Pleased

bob golding

Tesla list wrote:

> Original poster: "bob golding by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <yubba-at-clara-dot-net>
>
> HI all,
>     Been having some problems with the motor for my rotary. After designing
> the whole thing around a
> centrifuge brush motor  when I went to fire it up I discovered that the
> electronic controller has died :-(
> after trying to fix it I decided it would properly die as soon as I put the
> coil on anyway. It is a series
> wound brush motor with a start winding on one of the field coils as far as
> I can tell. it has three wires
> coming off it so I assumed that if I put a cap between the two wires coming
> off the field coils it should
> work. It does but doesn't seem to to have much torque. It is rated at 300
> watts and draws around 2 amps at 180
> volts. The cap I am using is 16 uF at 250 volts. It should turn my `12" x
> 1/2" rotor as the centrifuge hub
> that was on it is heavier than my rotor. Should the size of the cap affect
> the torque? I am leaving the cap in
> circuit when the motor is running. Will this make any difference. The motor
> spins up to 5500 RPM with no
> trouble without the rotor on. Help! I don't want to change the motor if I
> can help it as this will mean a
> major redesign.
>
> cheers
> bob golding