# Electric motorcapacitor starter ...

Discussion in 'Electronic Basics' started by :-), May 23, 2006.

1. ### :-)Guest

Well, I don't know how an electric motor capacitor starter works ?

from my old garage door opener, there' 3 wire going to the motor,
one is the Neutral, one for foward spinning and the other for reverse
spinning.
between the 2 last there is a condenser to help starting the motor ...

how do I used the cap to help stating the motor ?

2. ### :-)Guest

I googled that, but I have no idea yet what kind of motor mine is ...

http://www.lmphotonics.com/single_phase_m.htm

3. ### :-)Guest

Hmmmm, I didn't know that was few different king of one phase AC motor,
I thought they all work the same way ... I'll have to go downstair and
take a better look at the wire of mine

But hey I learn a few things tonight ;-)

4. ### John PopelishGuest

The capacitor advances the voltage peak in one winding compared to the
one that gets the direct connection to the power line. Without the
capacitor, and just one winding, the magnetic field produced inside
the motor just builds up, decays and builds up in the opposite
direction. This does not pull the rotor in either direction.

But if a magnetic field builds up across one diameter in the motor
(magnetized by the leading current through the capacitor), and then, a
little later, before that field decays, a second field builds up
(magnetized by the direct connection to the line), at right angles to
it, the rotor, that has been magnetized by the first field, is then
pulled over into alignment with the second field, so gets some
starting rotation. Then the first winding reverses its field, so the
rotor is pulled into a reverse position from its initial one, etc.
If you connect the line to the other end of the capacitor, the
second winding gets magnetized first and the first winding follows it,
so the rotor is pulled in the other direction.

Technically, this configuration is called a capacitor run motor,
because the capacitor does not get disconnected, after the motor spins
up. If there is a centrifugal switch (or some other means to
disconnect the winding that is fed current through a phase lead
capacitor), then it is called a capacitor start motor. If the
capacitor is made of two separate capacitors, and only one of them is
switched off after starting, it is called a permanent, split capacitor
motor.

5. ### :-)Guest

Yes

http://www.lmphotonics.com/single_phase_m.htm

After studiing my motor' wires, It seems to be a

4. Capacitor Star and Run
There's no switch so the cap is allways on.

And it's wire in a way we can start it on both directions .

Cool

6. ### John PopelishGuest

Here is a reference that goes into more detail, but calls your motor a
permanent split capacitor motor or PSC. They call the one with two
capacitors, one switched, and one always connected, a capacitor
start/run motor.