Single-Phase Soft Starter?

Yes - have a look at rswww.com under:

Electrical Automation & Cables > Control Gear > Motors & Motor Controllers

Never looked inside one but I understand they work the same way as 3ph soft starters: SCRs are used switch the AC line at startup, slowly ramping the conduction angle from 0-100%. This ramps up the applied voltage and hence the motor torque; initially reduced torque means a slower/softer start with less current inrush.

This torque-controlling works fine for starting/stopping, but it doesn't control induction motor speed (before anyone suggests attaching a lamp dimmer to their drill press ;) Running speed depends principaly on line frequency so is strictly VFD territory.

HTH Guy

Thanks Guy, I had a look there and found them. Probably a bit more than I wanted to spend on it though, as they seem to start from about =A370. I was hoping to find something about =A320 so it looks like I will be out of luck here.

Peter

Controllers

Thanks Guy, I had a look there and found them. Probably a bit more than I wanted to spend on it though, as they seem to start from about £70. I was hoping to find something about £20 so it looks like I will be out of luck here.

Peter

You could alway use the oldfashioned approach of a power resistor in series, with a slugged (delay) relay shorting it out after a few seconds. Or as Guy has said the scr option is pretty simple circuitry - only 4 components (a resistor, a capacitor, a diac, and an scr)

AWEM

That is 'probably' a Triac, not a Thyristor? Slight difference, but you wouldn't phase-angle fire a thyristor with a diac circuit.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

Peter is of course correct - loose terminology.

AWEM

Been there, done that! :-))

There is a lot of misconception on the two devices, and many a light dimmer has gone to that great scrapbin in the sky after the wrong replacement device was fitted, or it has been used to try and control and inductive device.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

Andrew,

Given the fact that my electronic knowledge and skill is pretty non-existent I fear that this would be beyond me, but thank you anyway for the tip. I have always had a problem with this, its a bit like electronic dyslexia. I am sure I could put it together if someone specced the components and drew a diagram( the idiots guide to circuitry!), but otherwise it would like a blind man doing a jigsaw puzzle:)

Peter

Andrew, I did reply to this yesterday but my response seems to have become lost somewhere.

Thank you for the suggestion, but I fear that making this is beyond my electronic skills or knowledge. I appear to have a form of electronic dyslexia. It's always been a problem for me, and no matter that I KNOW what a diode/resistor/capacitor etc is and what it will do I can only deal with them as individual concepts. Once they are together in any form my conciousness forgets what they do and cannot grasp how they work. Weird I know, but true.

If someone were to specify the parts and sketch a circuit diagram I could put them together, but otherwise It would be like a blind man doing a jigsaw puzzle:)

Peter

Andrew, I did reply to this yesterday but my response seems to have become lost somewhere.

Thank you for the suggestion, but I fear that making this is beyond my electronic skills or knowledge. I appear to have a form of electronic dyslexia. It's always been a problem for me, and no matter that I KNOW what a diode/resistor/capacitor etc is and what it will do I can only deal with them as individual concepts. Once they are together in any form my conciousness forgets what they do and cannot grasp how they work. Weird I know, but true.

If someone were to specify the parts and sketch a circuit diagram I could put them together, but otherwise It would be like a blind man doing a jigsaw puzzle:)

Peter