Explain pump motor start switch

Hi all, I helped my neighbor disassemble a pump motor, we had to remove the centrifugal assembly from the shaft. The centrifugal assembly opens a switch when it gets up to speed. Opposite of what I thought would happen. The motor has a start capacitor.

I just did a Google search thinking I might just answer my own question, but all I did was confirm what I thought I knew.

So, why does the switch open when the motor gets up to speed?

What is the circuit before the switch closes vs. after the switch closes.

Yes, I'm sure the switch is closed at stall and is pushed open when the weight swings. Mikek

Reply to
amdx
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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. :)

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Reply to
Michael A. Terrell

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

Reply to
Rheilly Phoull

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

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Reply to
amdx

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

Reply to
Maynard A. Philbrook Jr.

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.

Reply to
amdx

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

Jamie

Reply to
Maynard A. Philbrook Jr.

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