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Symptoms of Too Small a Start Capacitor for Submersible Well Pump Motor?

Discussion in 'Electronic Repair' started by [email protected], Apr 21, 2006.

  1. Guest

    Am trying to repair a submersible well pump that blew its start
    capacitor because the water storage tank check valve failed. Am glad
    to supply all the specifics if needed.

    I replaced the blown start capacitor with a new one of same rated size.
    Started up pump and it only ran for < 1 minute and pumped ~ 2-3 gal of
    water. Same thing happened when the old capacitor was going bad.

    The physical size of the new start capacitor is smaller than the one
    it replaced but the rating is the same.

    Am interested to find out what the symptoms are for too small start
    cap. Am wondering if it is better to error on a larger size?


  2. Do you really mean "start capacitor"? A start capacitor would only
    be used for a fraction of a second until the motor got up to speed and
    then would be disconnected by either a centrifugal switch or delay timer.

    If it is indeed a start capacitor, then whatever is supposed to disconnect
    it isn't working correctly and that's the real problem.

    --- sam | Sci.Electronics.Repair FAQ:
    Repair | Main Table of Contents:
    +Lasers | Sam's Laser FAQ:
    | Mirror Sites:

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
  3. Guest


    After posting was told that the 1/3 hp well pump failed some years ago
    and was replaced with same or similar pump but the original controller
    box was kept. It is just a basic box with start capacitor, relay and
    overload device.

    When the check valve failed the pump kept cycling and eventually blew
    the start capacitor. When I had the controller box open also checked
    the relay which tested OK but was unable to test the overload device
    becuase did not have the info. Will do some calling and test because
    it is the only part left to be checked.

    Have only run the pump 3-4 times since installed the new capacitor. As
    mentioned It runs for ~ 1/2 min and pumps ~ 2 1/2 gal water then shuts
    off. After a few seconds there is a noise. Sounds to me like
    mechanical contacts, do not know if it is coming from the overload
    device or relay but am guessing it is the overload device.

  4. spake thus:
    Yes; probably a thermal cutout switch, I would guess.

    Pierre, mon ami. Jetez encore un Scientologiste
    dans le baquet d'acide.

    - from a posting in alt.religion.scientology titled
    "France recommends dissolving Scientologists"
  5. I wouldn't expect them to chatter under normal conditions, so that sounds
    like a place to begin. The start capacitor should only be in the circuit
    for an instant - if you put an multimeter on the highest AC range across it,
    there should only be AC for that short time but when it gets disconnected,
    there will probably be some DC remaining on it.

    --- sam | Sci.Electronics.Repair FAQ:
    Repair | Main Table of Contents:
    +Lasers | Sam's Laser FAQ:
    | Mirror Sites:

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
  6. lsmartino

    lsmartino Guest

    Could it be that the motor pump is seizing. The sequence of events
    would be something like:

    a) The pump tries to get to speed with the capacitor connected. It
    reaches the operating speed and the startup relay opens.

    b) Without the startup cap, since the motor is seizing, the pump starts
    to lose speed and draws more amperage... thus closing the startup relay
    again (and the power consumption gets higher too)

    c) The pumps gets again to speed. The startup relay opens again, but
    the motor looses speed and the relay closes again, thus repeating the
    cycle. (this would explain the relay chatter)

    d) Enventually the thermal cutout switch opens because of the excesive
    current draw.

    Do you have an AC ammeter? You should check how many amps is the pump
    consuming. That should show you if the pump is within it´s normal
    power consumption or not. If the consumption is too high, the motor is

    Other way to test this is replacing the startup relay by a momentary
    contact push switch, and using an ammeter to monitor the power
    consumption of the pump. You initially turn on the pump and push the
    contact switch to make it start. As soon it gets to speed (probably in
    a second or less) you release the switch, leaving the startup capacitor
    out of the circuit. Check the amperage, if the pump starts to draw more
    an more amperage without the capacitor connected, then you will know
    that the pump is seizing.

    Good luck.
  7. Guest

    Sam, David, and Ismartino

    Thanks for the suggestions.

    First will try to clear up any misunderstanding. Nothing is
    "chattering". Will try to be more clear this time. The few times I
    have run the pump since the check valve failure, blown start capacitor
    and replacement start capacitor have used this sequence. Turn on pump
    switch and pump runs for ~ 20 sec and pumps ~ 2 1/2 gals then stops. I
    turn off the switch and a few seconds later hear a "contact like
    noise"(like relay contacts either making or breaking).

    Specifics This submersible well pump is a RedJacket 1/3 hp 230V
    single phase 3 wire Model 33 M1. The control box is a "town and

    After the blown start capacitor the 1st thing done was to check the
    resistance of the motor windings which were OK. Also checked the relay
    and it was OK. Since posting was able to get the test value for the
    Overload Device and it checks OK. Only problem something is wrong
    since pump stops after ~ 20 sec.

    As previously mentioned am guessing it is the overload device. When
    the pump is running can not hear the relay or overload device

    The only Digital MultiMeter I have is a Sears Craftsman Model 82141.
    Checked AC and it lists 10A. Have never used it for measuring current
    for a 230V electric motor so will need some hand holding. The specs I
    could find for the Model 33M1 motor are

    normal 5.3
    idle 3.5
    lock rotor 20

    Is there some way I can send the schematics? Or are all single phase
    230V pump motors with mech relay, start caps and overload protection
    the same?

  8. lsmartino

    lsmartino Guest

    Without an AC ammeter you can´t diagnose what is wrong. You really
    NEED to know how many AMPS are your pump consuming. I still think the
    pump has a mechanical problem and it is consuming too much amperage.
    You need an AC Clamp Ammeter like this one:

    Don´t *even think* to use your DMM to measure the amperage. The LRA
    amp rating of the pump are 2 times the maximum amperage supported by
    your DMM and you can blow the DMM.
  9. Guest


    Thanks for the warning and link to Sears Clamp Ammeter!

    Update found out that the Overload Protection Part was designed to
    protect both 115 and 230 Volt pumps. Took it out and everything ran
    OK. No shutdowns....

    The pump repair person who checked the control box when the capacitor
    blew said the overload device was wired incorrectly so after getting
    the new cap installed as suggested. Since everything is running OK
    with the Protection Part removed and the part tests OK am guessing the
    suggested wiring for it is incorrect for 230 V.

    The Overload Protection Part is a Klixon TA5 that is no longer made and
    Klixon does not have a part that will interchange with it.

    Would be interested in any suggestions concerning tracking down correct
    wiring for it.

  10. lsmartino

    lsmartino Guest

    I couldn´t find anything by Klixon TA5... aren´t there other numbers
    on the Klixon protector? Even a picture of the protector would be
    great. Maybe TA5 means 5 Amp... but I´m not sure.

    If there are other numbers printed on the component, please post them
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