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Thread: 2 Speed Pump Shuts Off On High

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    2 Speed Pump Shuts Off On High

    I have a 2 speed Pentair Dynamo pool pump P/N 340221. I discovered today that when I switch over to high speed the motor turns off after 30 seconds or so. After a minute or so it turns back on only to repeat the process. From what I read, it may be that the thermal overload is responsible for shutting it down, but I need to find out why. But, I feel no excessive heat at all. I checked voltage and I have a constant 117 volts at the motor when its running. While its not a typical bad capacitor symptom, could a bad capacitor cause this problem. I know typically a bad capacitor will prevent a motor from starting (giving the hum noise), can a bad capacitor cause a motor to shut down after the motor has started? Just trying to brainstorm without throwing unneeded parts at this thing; my thoughts are that the capacitor is being depleted of energy faster than it can be replenished. Does anybody have any other ideas? Thanks for any input...

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    JasonLion's Avatar
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    Re: 2 Speed Pump Shuts Off On High

    Welcome to TFP!

    It could be a bad run capacitor, different from the start capacitor you describe. I would also double check to make sure that the low speed power connection is not active at the same time as the high speed connection.
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    Re: 2 Speed Pump Shuts Off On High

    thanks for the quick response. Is there a separate run capacitor? I only find one on the end, it does not have the external "hump" I have seen on other motors. I am having to replace the toggle switch (due to me cracking the switch housing when I was taking the cover off) so that should eliminate the question of both high and low connections being active.

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    Re: 2 Speed Pump Shuts Off On High

    The capacitors on AC motors just provide phase shift to keep the forces happening at the right time. Most pool pump motors have a start capacitor, but not a run capacitor. A bad start capacitor won't cause problems after the motor is running.

    You might pull the back off the motor to see if insects have clogged the ventilation ports.
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    Re: 2 Speed Pump Shuts Off On High

    Boy, this one really has me scratching my head. thanks for the quick responses. John I took the cover off and blew dust and spider webs out but still had problem. I can't imagine having to replace the entire motor, it only has 2 seasons on it. Are there any other parts in the motor that would wear out?

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    Re: 2 Speed Pump Shuts Off On High

    Just guessing here: Are you measuring your voltage from the line to neutral or line to ground? Though they should be the same, the motor uses the neutral, and a loose neutral can cause motors to overheat.

    Having a little trouble finding out what motor you have. Pentair's site shows a motor with no top-mounted capacitor, but some sites show what they claim is the OEM replacement motor with a top-mount cap.
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    Re: 2 Speed Pump Shuts Off On High

    It is possible for the high temperature cutout switch to fail. High speed would be a little warmer than low speed, which might be enough to trigger it if it is broken.
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    Re: 2 Speed Pump Shuts Off On High


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    Re: 2 Speed Pump Shuts Off On High

    Is there a high temperature cutout switch available for this motor? a part number would help me a bunch. thanks

    - - - Updated - - -

    John I was measuring to the neutral where it screws on to the motor from the power cord. I'm trying to decipher the motor label as well... does this indicate that it is an AO Smith 177803 motor?

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    Re: 2 Speed Pump Shuts Off On High

    If you switch the motor from low to high while low is running, does the motor continue to run?
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    Re: 2 Speed Pump Shuts Off On High

    That motor may be a BN50 or BN60
    http://www.spapumpsandmore.com/spa_p...raos-15115.htm
    or
    http://www.spapumpsandmore.com/Centu...aos-186022.htm

    Check out this link: [url]http://www.centuryelectricmotor.com/3400_MMU_Pool.pdf/url]
    The link will bring you to Motor Mastery University. Check out page 25. Thermal Overload check. Also when you turn the shaft does it turn smoothly?
    Last edited by bobodaclown; 03-25-2015 at 09:08 AM. Reason: updated link
    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

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    Re: 2 Speed Pump Shuts Off On High

    Quote Originally Posted by tley View Post
    Is there a high temperature cutout switch available for this motor? a part number would help me a bunch. thanks

    - - - Updated - - -

    John I was measuring to the neutral where it screws on to the motor from the power cord. I'm trying to decipher the motor label as well... does this indicate that it is an AO Smith 177803 motor?
    I think you are right on the motor.

    How long has this been going on? Any idea when the last time it worked right, and anything that might have changed between now and then?
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    Re: 2 Speed Pump Shuts Off On High

    mas, the motor will run for up to a minute then turn off.

    John last it worked was right up to our first freeze (November or December). The motor did freeze up due to me forgetting the darned timer shutting down the motor during a cold blast. The lid lip on the pump pot (where the strainer is located on the pump) broke from the water freezing. To the best of my knowledge the motor was only "trying to run" but couldn't due to ice for a couple hours. I have replaced the pot and started the pump up on Friday to discover the problem with high speed.

    - - - Updated - - -

    bob, shaft turns smooth. Motor runs smooth and quiet.

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    Re: 2 Speed Pump Shuts Off On High

    The freezing might have damaged the seal and is creating higher load than normal. This will cause the motor on high speed to turn off but after a few minutes it will turn on again. When you had the pump apart did you check the seal?
    Mark
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    Re: 2 Speed Pump Shuts Off On High

    I checked the o-rings but did not look at the shaft seal. When I go to check it, what am I looking for? Or do you suggest just changing it for good measure? Question about seals... do you guys recommend the pentair brand seal or is the US Seal brand an acceptable replacement? only reason I ask is the pentair brand is 3X the price and looks different.

    - - - Updated - - -

    And when I have it tore down, is there a way to check the high temperature cutout switch?

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    Re: 2 Speed Pump Shuts Off On High

    Check the link I posted earlier. It has how to check the switch.
    Should have been this link: http://www.centuryelectricmotor.com/3400_MMU_Pool.pdf page 25.

    Protector (Thermal Overload) Check
    • Set ohmmeter to R x 1.
    • Resistance between terminals:
    1 & 2 should be approximately 0 (Disc.)
    2 & 3 should be approximately 0 (Heater)
    • Replace if either value exceeds 1 ohm.
    TIP: Motor cycling on overload indicates some other problem not just a defective overload.
    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

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    Re: 2 Speed Pump Shuts Off On High

    thanks bob. that link is a lot more help. but, it looks like i am going to have to totally disassemble to motor to access it (at least on my model) which brings me back to an unanswered question:

    do you guys recommend the pentair brand seal or is the US Seal brand an acceptable replacement? only reason I ask is the pentair brand is 3X the price and looks different.

    thanks again for everyone's input

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    Re: 2 Speed Pump Shuts Off On High

    I'm not positive but pentair doesn't produce their own seals, they contract them out.
    Looks like its a standard PS-200 shaft seal looks like you can get it for $6.50 delivered.

    http://www.ebay.com/itm/Replacement-...item4858850d89

    http://www.ebay.com/itm/New-Pool-Spa...item3a9bd54f3c
    Upgraded seal: $11.95
    http://www.ebay.com/itm/Sta-Rite-Sup...item4634f8e258


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    Re: 2 Speed Pump Shuts Off On High

    Just wanted to let everybody know first of all thank you for the help and secondly what seems to have fixed my problem should anyone else run into similar symptoms. The problem did end up being a faulty thermal switch. I especially want to thank Bob for posting the instructions to test the switch, it was essential in diagnosing the problem, and made me feel like a genius in the following story:
    So I went to the local electric motor shop (just as a disclaimer this really is a very busy shop with a great crew working for them, have done business with them for awhile and will continue to do so) requesting a thermal switch. Guy wanted to know what symptoms I had, which I explained, he did not believe thermal switch was problem. Being the hobbyist that I am and not wanting to throw useless parts at the thing I let the guy "check it out" for free. Pick up motor, shop put new internal switch in, brought it home, same problem. Back to the shop with it and back home, same problem. Shop agrees to come out to the house and check my setup, they can't get it to duplicate the problem at the shop. Guy comes out checks my power supply and determines that I must be right that it needed a thermal switch. Installed thermal switch 2 weeks ago now and seem to be problem free. The shop explained that thermal switches don't tend to be "sorta broke" they usually completely fail. I don't know, but it sure did feel good to be right when up against the professionals.
    Thank you again.

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    Re: 2 Speed Pump Shuts Off On High

    All's well that ends well.
    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

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