Explain pump motor start switch

A

amdx

Guest
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
 
amdx wrote:
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.
Click to expand...

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. :)

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
 
On 17/07/14 20:59, amdx wrote:
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

Why did you think the switch should close at speed ??
Click to expand...
 
On 7/17/2014 8:22 AM, Rheilly Phoull wrote:
On 17/07/14 20:59, amdx wrote:
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

Why did you think the switch should close at speed ??
Click to expand...

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


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In article <lq8hb5$mn2$1@dont-email.me>, nojunk@knology.net says...
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?
Click to expand...

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
 
On 7/17/2014 5:48 PM, Maynard A. Philbrook Jr. wrote:
In article <lq8hb5$mn2$1@dont-email.me>, nojunk@knology.net says...

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?
Click to expand...

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.
 
In article <lq9s7q$q7q$1@dont-email.me>, nojunk@knology.net says...
On 7/17/2014 5:48 PM, Maynard A. Philbrook Jr. wrote:
In article <lq8hb5$mn2$1@dont-email.me>, nojunk@knology.net says...

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?


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.
Click to expand...

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

Jamie
 
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