"RBnDFW" wrote...


You want to use if for a drive clutch, or a motor brake?
If a drive clutch, that coil may require up to 30 amps of 12V.
Not sure what you would gain by adding a clutch

Well, I was looking at using it as a drive clutch - having only single-phase
230V I'm limited to a single-phase motor, and they don't much like being
started and stopped too often, tends to shorten the life of the centrifugal
switch and windings due to the increased start current (the run cap's 25uF
versus the 150-200 uF for the start cap, likely to be 6 to 8 times the
current on start-up) - hence the intention to run it continuously and use a
clutch in the drive to the spindle.

With 12V on the coil as per use in the car it came from, it locked up pretty
solid, couldn't shift it with a self-grip wrench, and it was drawing about
4A from a DC supply - I'd guess that in its intended application it'd be
running at upwards of 2000 RPM and transferring perhaps 4 or 5 HP, that's
about the power loss for aircon in most medium-sized cars - my rule of thumb
was the RPM x torque = HP, so if the RPM's halved so's the power, might
transfer 2 to 3 HP?

Re motor braking, I'm aware of quite a few lathes that use DC injection
(mostly at the high end?), and some 3-phase inverters have the feature,
stopping the chuck in less than a ritation - seems a sensible safety
measure?

Dave H.
--
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" -
Douglas Bader