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Single Phase Motor Test

Discussion in 'Sensors and Actuators' started by Marius Muller, Nov 8, 2017.

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  1. Marius Muller

    Marius Muller

    Apr 8, 2017
    D410FA9F-0F0E-4887-9108-2783683F1CF8.png I have a salmson single phase motor 1.1 kw.The motor is used as a pressure pump,water pressure falls pump swithches on to boost pressure and off when done.This motor switches on and off numerous times a day maybe 100 times or more.My Question;the starting cap basically melted and must be replaced motor ran 10 years,I checked the windings and earth connections all is well,I replaced the cap with a new one ,the
    Motor starts and runs.As far as I understand the cap (there is only one on this motor) is taken out of circuit as soon as the motor runs on the RUN winding.The cap is in series with the start winding.While the motor is running I measured with a clamp meter on one of the cap leads 3.4 amps BUT the amps stay there continuously ,it looks like the cap is always in the circuit.Is this correct?It is a plastic type cap ,will it not overheat?I believe some motors do keep the cap in circuit for extra torque.I find no info regarding whether the cap stays in or is taken out after start.Is there any way to know .I see no mention of a centrifugal switch.
  2. Minder


    Apr 24, 2015
    You can usually know by the capacitor value, on PSC (permanent start cap) motors, the value is relatively small compared to cap start motors.
    These PSC motors are common on smaller pumps and fans.
    If you replace it I would stay away from Chinese origin. They are known to have a high failure rate, also look for AC motor run rated type.
    Try and obtain N.A. manufturer.
    [email protected] likes this.
  3. kellys_eye


    Jun 25, 2010

    As above. Buy cheap, buy twice.
    [email protected] likes this.
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