Single phase induction motor start up problem

[OldWood]

Many thanks for that, Bob, but please do not do anything that takes up your time as Mr Sod and his associated Law have just paid me a visit. My bench testing cannot reproduce the fault - at least 50 starts on a B16 breaker and not one failure (wonder why I put a 16A breaker on my workshop ring? - perhaps it was all I had at the time).

So back to the club on Monday with it. Don't like faults like this. What have I done? Waggled the centrifugal switch a bit, taken the capacitor off and put it back, added a little grease to the plenty that was already on the oscillator mechanism. Can't see any of that having a contribution.

We'll see what Monday brings - it will be very curious if the fault is there then.

Thanks for helping

Rob

 

[Tusses]

Interesting thought but somehow seems a bit of overkill for something with a 650W motor and driving a load with very little inertia.

Bob - any thoughts on the idea of odd voltages occurring ?

Rob

My Thicknesser is only 1HP (750w), it still sucked a load of power on start up.

 

[9fingers]

Planers & thicknessers are amongst the worst culprits for high starting currents and longer start up time as not only has the motor to get up to 2850 rpm, there is a belt drive and a heavy drum to get up to 4000 -5000 rpm as well before the motor can hit synchronous speed and the starter winding disconnect.

Bob

 

[OldWood]

My Thicknesser is only 1HP (750w), it still sucked a load of power on start up.

Lot of inertia there - the block has quite a mass and it takes quite a bit of power to get it moving at speed. The bobbin sander is just a couple of inches of small diameter shaft with sandpaper round it.

Rob