Explain pump motor start switch

The start winding draws a lot of current, and is only needed to get the motor started. That start capacitor is a non-polar electrolytic. It can only take intermittent service without blowing the vent. The start capacitor causes a phase shift to the run winding, which provides the torque required to start the motor. At least it isn't using a potential relay. :)

Why did you think the switch should close at speed ??

Never mind. I don't know how I got my logic mixed up. Thanks, Mikek

Centrifugal force. The spring that is holding the contacts together will be pulled back via the linkage that gets forced to the outside of the spin.

And also, you only want the cap in circuit on initial start.

You can get add on switchings to hang on shafts to do these wonderful things.

An electronic starter will monitor the current and when the initial current drops off, the electronic switch disconnects the starting cap. Those types of electronic switches normally use a reed switch with a couple of turns of wire around the read to sense current. The switch turns on a triac. Also, you may see a washer wrapped up in the turns to create a shaded pole to prevent the reed from chattering.

Jamie

I have already explained, I got my logic backwards. I understand how it works. Then my question was poorly ask. What I meant to sask, what is the function performed when the switch opens at speed? Ans. Stops current flow in the start winding.

nuf said, Mikek

I'm embarrassed, well, a little bit.

No, you're very red in the face! :)

Jamie