Diagnose pump motor issue?

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Isaac-1

Isaac-1

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May 10, 2010
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SW Louisiana
My 3 year old 2 speed pump motor has started making a strange noise, and I am not sure where to look for the problem. It has started making a loud Awwwkkkzzz sound whenever it starts up or switches from low to high speed. This is a brief sound, maybe 1/4 second (about as long as it takes to say Awk), the sound has slight buzz to the end of it almost like saying Awk with is lisp. Other than this new noise the pump seems to be working as normal.

Any thoughts?

Ike
 
Only start capacitors use a centrifugal switch. I think that the capacitor is a run capacitor and is in the high speed windings only.

Also, the problem happens when switching from low speed to high speed. Even at low speed, a centrifugal switch would be open.
 
The FloPro does use a PSC motor for the single speed model. However, I believe all two speed motors require a centrifugal switch (or electronic) because otherwise you would need two starter winding's and two PSC capacitors and as far as I know, they don't build a motor like that because it would require 4 windings. A two speed motor needs to be able to start on low or high setting.

The replacement motor for that pump (B983) uses a PSC high speed winding but a switched start capacitor winding for low speed. The B2983 is a CSCR for the low speed but that too requires a centrifugal switch.
 
So, all two speed pumps use a centrifugal switch? But, just for low speed?

Even if it does, the problem doesn't seem to be happening when starting on low speed. Or, does it happen when starting on low?

And, when switching from low to high, the motor is already spinning. That should mean that the switch is open

.
 

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Well I went out and shot a video today, and it is not making as much noise when switching as it was yesterday, the loudest time today was switching from high to low, yesterday it was louder starting or switching from low to high. I will try to upload the video to youtube and post a link here shortly. Please ignore the pump loosing prime on high, the water was still a little low in the skimmer from the DE change yesterday and I was bypassing the solar heat when manually switching to high today which allowed for just enough extra flow to let the skimmer suck air. I was going to redo the video after adding water to the pool, but did not find a quiet time in the mechanical room to do it, the well pump and the water pressurizing pump are both in that same room, water was being used around the house (laundry, etc.) so the pressurizing pump (variable speed pump) was revving up and down, etc.

Ike

p.s. after reviewing the video the sound does not come through much I will try to re-shoot the video tomorrow and try to capture the sound better it is getting lost in the background noise on the current video

p.p.s. since everyone seems to suspect the capacitor I will try to test it and report back also
 
JamesW said:
So, all two speed pumps use a centrifugal switch? But, just for low speed?
Click to expand...


Well, they need a switch of some kind. I have seen electronic switches on some newer motors but I don't think they have made it into residential pump motors yet as they are much more expensive.

The centrifugal switch can have two purposes. One to switch in and out the start capacitor and the other is to switch the speeds during the start process. It just depends on the design.

I have seen two speed designs where they start the motor on low speed and then switch to high if necessary and some designs where they start on high and then switch to low if necessary. The later has higher starting torque.

I am not entirely sure which design is used for this particular motor but given the high speed winding is PSC, I would use that to start the motor and then switch to low speed if wired that way.
 
I checked; the two speed pump motor does have a centrifugal switch. It does not have a start capacitor. I think that the centrifugal switch is only used on low speed for starting. There is a run capacitor. I think that it is used only on the high speed windings.

Since the problem happens when switching speeds, I would suspect that the switch that changes speeds is going bad.
 
A PSC run capacitor is for starting the motor as well and is always in the starter winding loop just like a start capacitor and a standard run capacitor. The only difference is it remains in the winding and the winding remains energized. It helps increase the efficiency of the motor. So they must use that for starting on high speed and then switching to low speed which I think most PSC 2 speed motors do.

And I would agree that any buzzing or arcing could be from the switch. The contacts do corrode over time and a little emery cloth can usually clean them up.
 
A two speed motor has two sets of windings. Both sets are connected at one end to the common leg of a 240 volt supply. The other leg of the 240 supply is switched from one set of windings to the other. The pump can start on high or low depending on which set of windings has the variable leg connected.

I think that the high speed is a normal PSC motor with the run capacitor, which does not use a centrifugal switch.

I think that only the low speed uses the centrifugal switch. I think that it's a split phàse induction motor.
 
A single speed PSC motor has two winding's, the main and the starter winding. The starter winding is rotated 90 degrees off of the main winding but still a two pole winding. The starter winding always has the capacitor whether it is a PSC or CS motor. That's what gets it to start. The capacitor never goes in the main winding either high or low speed start.

A two speed PSC motor has three winding's, high speed, low speed and a starter winding. The high speed and starter is the same as the single speed but the low speed has to be a 4 pole winding in order to get the lower speed.

Assuming the starter winding is paired with the high speed winding, after starting, the switch would then switch out the high speed and starter and switch over to the low speed winding.

Here is a diagram for one way to do it but it is missing the centrifugal switch which is necessary:



Capacitor+Motors+7A+copy.jpg
 
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