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Old 12th May 2020, 10:07 pm   #1
Tractorfan
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Join Date: Mar 2008
Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.)
Posts: 3,177
Smile Motor soft starting

Hi,
I have a water pump that uses a single phase induction motor with a capacitor permanently in circuit of about a quarter hp at 230 volts. (Is that called a split phase motor?)
I would like it to start at a reduced torque to avoid pressure shocks to the pipework.
I've been kicking ideas around such as a resistor, diode or even a transformer with a bucking winding that is shorted out after a short period when the motor is at speed.
I've looked on eBay, but most soft start units there seem to be for star/delta starting of polyphase motors.
Ideally it would ramp up to full revs (which, of course, it won't with my simple ideas), but I'd happy if it started in two steps.
Another thought is, maybe, a gadget that reduces resistance as it heats up (I can't think what they're called), then is shorted by the aforementioned timer.
Any thoughts appreciated.
Cheers, Pete.
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