I've had two tools die on me in the last fortnight. The first was a
cement mixer and the second a table saw. Both had induction motors
and in both cases it was the capacitor that supplies the starting
torque that failed... an acrid smell followed by a humming and a
failure to rotate, cured by a shove to the blade or barrel.

Both tools were under guarantee and the manufacturers were happy to
put spare capacitors in the post but since I generally take care of
tools and don't recall overloading either of them, I was wondering
what put the kibosh on the capacitors in the first place?

The mixer manufacturer said that the capacitor should cope with a full
load from a standing start even though they recommend starting the
drum empty.

Is capacitor failure a general problem with induction motors?

Mike

mike wrote:
I've had two tools die on me in the last fortnight. The first was a
cement mixer and the second a table saw. Both had induction motors
and in both cases it was the capacitor that supplies the starting
torque that failed... an acrid smell followed by a humming and a
failure to rotate, cured by a shove to the blade or barrel.

Were you at the time starting them frequently?
The capacitor is not rated for the continuous starting current, just
intermittent.

They can also dry out over time.

Ian Stirling wrote in message ...
mike wrote:
I've had two tools die on me in the last fortnight. The first was a
cement mixer and the second a table saw. Both had induction motors
and in both cases it was the capacitor that supplies the starting
torque that failed... an acrid smell followed by a humming and a
failure to rotate, cured by a shove to the blade or barrel.

Were you at the time starting them frequently?
The capacitor is not rated for the continuous starting current, just
intermittent.

They can also dry out over time.

Thanks for the reply.

Yes, they'd been started fairly frequently at the time. The table saw
is a cheapie but I'd have expected the mixer to be made of sterner
stuff.

"mike" wrote in message
om...
I've had two tools die on me in the last fortnight. The first was a
cement mixer and the second a table saw. Both had induction motors
and in both cases it was the capacitor that supplies the starting
torque that failed... an acrid smell followed by a humming and a
failure to rotate, cured by a shove to the blade or barrel.

Both tools were under guarantee and the manufacturers were happy to
put spare capacitors in the post but since I generally take care of
tools and don't recall overloading either of them, I was wondering
what put the kibosh on the capacitors in the first place?

The mixer manufacturer said that the capacitor should cope with a full
load from a standing start even though they recommend starting the
drum empty.

Is capacitor failure a general problem with induction motors?

No. Are you running them from mains or a generator. If the latter suspect
this isn't performing to spec.

"G&M" wrote in message ...

Is capacitor failure a general problem with induction motors?

No. Are you running them from mains or a generator. If the latter suspect
this isn't performing to spec.

Thanks for the reply. They're both being run from the mains.

In message , mike
writes
I've had two tools die on me in the last fortnight. The first was a
cement mixer and the second a table saw. Both had induction motors
and in both cases it was the capacitor that supplies the starting
torque that failed... an acrid smell followed by a humming and a
failure to rotate, cured by a shove to the blade or barrel.

Both tools were under guarantee and the manufacturers were happy to
put spare capacitors in the post but since I generally take care of
tools and don't recall overloading either of them, I was wondering
what put the kibosh on the capacitors in the first place?

The mixer manufacturer said that the capacitor should cope with a full
load from a standing start even though they recommend starting the
drum empty.

Is capacitor failure a general problem with induction motors?

Yes

--
geoff