parvalux

[martin haysomParticipant @martinhaysom48469]

i have a small Parvalux motor with reduction gearbox. it wont run so i thort i would ask before i take it apart. it has 3 wires out 1 black and 2 white and a capactor . black wire to power. white wires of motor and cap joined together as instructed on capactor . it just hums its free to rotate. tested with no load. i bought it second hand and have never had it running. idea’s please.

[Clive Brown 1Participant @clivebrown1]

Wiring the capacitor across the 2 white wires is correct. Then apply live ac to one of those junctions and neutral to black, If that doesn’t work then the motor probably has a fault, assuming the capacitor is a suitable one.

[noel shelleyParticipant @noelshelley55608]

Is the cap the right one ? Is it up to spec ?  Check correct wiring. I think I have one like it . Give us more details on the motor. I will check the wiring on the one I think I have.  Noel.

[Robert Atkinson 2Participant @robertatkinson2]

Model number and a picture of the motor and data plate(s) please.

Parvalux make and made hundreds of different models and types of motors.

Robert.

[BazyleParticipant @bazyle]

Will it run if you help spin it up by hand?

[John HaineParticipant @johnhaine32865]

It sounds exactly like the motor I have on my Quorn, an SD15 I think.

If you have a multimeter check continuity between black and each white. If one of the whites is open circuit the motor is probably scrap. White windings should have the same resistance.

If the windings are both OK the wiring is as Clive suggests. Depending on which cap/white junction you connect to the motor should run one way or t’other. If not the cap it probably shot. A single pole changeover switch can then be used to select forward or reverse.

If it needs a new cap the value on mine is 8.4 uF 440 V.  Get a cap designed for motor use. They are pretty cheap.

https://uk.rs-online.com/web/p/film-capacitors/3779074

[GreensandsParticipant @greensands]

Whst is the difference between a motor start capacitor and a motor start and run capacitor and how do you know which is the appropriate choice to make?

[Robert Atkinson 2Participant @robertatkinson2]

A start capacitor carries a larger current but only for a few seconds. They are often larger value. A run capacitor carries current all the time the motor is running. Typically a run capacitor uses thicker plates to reduce resistive losses and internal heating. This makes them larger and more expensive for the same capacitance and voltage.
You use a start apacitor on a start winding and a run capacitor on a run winding. The datasheet for the capacitor will tell you it’a intended application.
The RS capacitor linked to by John is a start capacitor.  However given it’s high voltage rating, the small motor size and the likelyhood that the motor is not running for hours at a time it is probably OK for this use. It would not last as long as a run capacitor of the same voltage.

Robert.

[noel shelleyParticipant @noelshelley55608]

The most obvious difference is the value, their both capacitors, the higher value will be the start and the lower the run. BUT there are many types of motor, types of duty and many circuits, there is no simple way to know the right value for a given motor. Good luck. Noel.

[noel shelley]

On noel shelley Said:

The most obvious difference is the value, their both capacitors, the higher value will be the start and the lower the run. BUT there are many types of motor, types of duty and many circuits, there is no simple way to know the right value for a given motor. Good luck. Noel.

The value has nothing to do with if the capacitor is rated for use as for start or run duty. A start capacitor for a small motor could be the same value as the run capacitor for a large one. Depending on the motor design there may be a start capacitor, a run capacitor or sometimes one of each.
The duty (start or run) depends on the detail internal design of the capcitot and the materials used. A run capacitor can be used as a start capacitor without issue but using a start for run requires care.

Robert.

[martin haysomParticipant @martinhaysom48469]

thanks for the replys

done a few checks

105 ohms across 2 white wires

53 ohms across black to white wire

and same to other white wire

capacitor is marked 3uf

dont know how to check it but cant charge it with a megger

[John HaineParticipant @johnhaine32865]

Probably duff then.

[martin haysomParticipant @martinhaysom48469]

new capacitor ordered

[martin haysomParticipant @martinhaysom48469]

update. new cap arrived and fitted. motor would not run so i took the motor apart except the gearbox would not come off the shaft could find nothing wrong so put it all back together and it worked. the gearbox is full of nice clean grease but i would still like to strip it as i think some thing is not right

[martin haysomParticipant @martinhaysom48469]

it didn’t work for long, so i took the gearbox off. no problem with motor but the gearbox has a tight spot. now i need to work out how to get the shaft out

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