Andrew Gabriel wrote:
In article ,
John Rumm writes:
geoff wrote:
100uF sounds quite high, are you sure that's right?
Well it is what is written on the side of it:
http://www.internode.co.uk/SIP/DSCN5328.JPG

I just checked a Clarke induction motor I have here.
That's got a 75uF start capacitor, for a 510W motor.
That's probably OTT for starting the drill press which
isn't going to have any significant starting load, but
I suspect the motor is probably more general purpose
and may also be used on machinary which does have a
starting load. (Clarke do also sell just the motors.)

This is 750W, but again not much starting load (although I expect the
fan load becomes significant before the motor is to full speed).

Rather than trawl round too many shops I phoned SIP earlier and got them
to direct me at an authorised spares place. Prolly cost a bit more that
way (£14 inc delivery) but saves too much farting about.

I had to replace the capacitor in my lawn mower a few years
back. That's a 1200W or 1600W motor (can't recall), but I
think the capacitor was a lot less than above, so you can't
necessarily tell just from the motor power. (OTOH, I
suspect that might be a run capacitor rather than just a
start capacitor.) The capcitor died slowly in that case,

These often seem to be smaller capacitance than the start ones.

it gradually got less and less starting torque (less able
to start with any grass around the blade), and finally
had to be started by hand (not brilliant for a lawn mower;-)

Yes I can see that may have a H&S bod squirming ;-)

and would happily run in either direction. When I got inside
to the capacitor, it had spewed it's contents out (slowly
I guess), which had set solid again as it cooled outside
the case.

The case on mine looked a little worse for ware, and the inside of the
housing was damp with what looked like leaked electrolyte, but no major
show of guts! Having said that, it was showing diddly squat in the way
of capacitance - a large wedge of DC series resistance you could see on
a high ohms range, but 100uF it sure wasn't!


--
Cheers,

John.

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