Speed Control of Single Phase Motors

A question for the electrical engineers here as I have no idea if what I want is even feasible or not, never mind how it can be achieved.

My mill is powered by a 1hp capacitor start single phase motor. What I would like to have is a mill motor with variable speed control (but which will not overheat by going too slowly!).

Is this possible to provide some form of variable speed control for the motor I have, and if so how do I do it, or do I need to go down the "three phase motor with inverter control" route instead?

Chris

I think the simple answer is no, or we would all have done it. There are single phase motors which can be speed-controlled, and with a DC motor this is even easier. But the advantages of the 3 phase route - small motor, quiet operation, wide speed range etc, have so far won the day. If you would like a spare single phase motor to play with in your search, I have one - but so have most of us, I suspect. Sorry!

Cheers, Tim

Hi ChrisH

I keep seeing Variable Speed Pulley driver systems on the internet. I have no experience of them. Maybe that avenue could provide a solution?

Steve

Tim, I feared that be the case! Oh well, start saving I suppose!

Steve, I will look on the internet for a variable speed pulley systems, my lathe came with one so I am familiar with the concept, good idea.

Chris

I've had good luck on ebay going for 'parts or not working' inverters where the ads specify that they are untested (or removed from working equipment) rather than known faulty - not paying more than £20-30 and sticking to sellers with good feedback. Google the model number to check that it accepts 240V single phase in, what motor power it will handle (if not obvious from the listing) and that there's a manual you can download, before bidding. Think I have had three like that so far and all worked perfectly. Used three phase motors are plentiful on ebay too, often for just a few pounds if you can collect (again check that they can be wired for 240V).

Only problem is that once you get hooked you'll want to convert every single motor in your shop to three phase!

hi gents

Any Idea how the washer manufacturers do it for the spin speeds 400, 600, 900, 1200, 1400, 1600 rpm from a single 240V motor

Rufus

Easy,

Various ways from tapped field coils to  programmer with inbuilt speed controller with tacho generator on back of brushed motor

More up market ones use a brushless motor...

Edited By John Rudd on 23/11/2015 22:10:09

Hi this is not a single phase cap start but a single to three phase controller and a three phase motor that does instant reverse for the agitator cycle.

This is the motor I am familiar with

http://www.directdrivemotors.com/history.cfm

Apology to Chris for the intrusion

Eric

Edited By oldvelo on 23/11/2015 22:16:24

Thought this might be of interest. I was looking around that other site (mem ahem) and came across a link to a CVT mod on a mill drill. There is a video on the Home page the link points to.

**LINK**

Steve

Edited By Steven Vine on 25/11/2015 13:24:11

Edited By Steven Vine on 25/11/2015 13:28:00

The principal of variable speed pullies is described in the attached link - years ago there was articles on how to build one - can’t remember the magazine - link http://www.berges.de/download/e/11_03_23_BERG_DA_RD%20b_E6.pdf

I have a variable speed pulley fitted to my Axminster wood turning lathe.

I think the lathe is the old M950.

Very effective it is too, the variable speed that is.

Len. P.

Edited By The Merry Miller on 25/11/2015 15:18:49