By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Until July 27th

Change of direction a single phase capacitor run motor

All Topics | Latest Posts

Search for:  in Thread Title in  
martin perman14/12/2018 10:28:11
avatar
1587 forum posts
66 photos

Gentlemen,

Can anybody advise on the change of direction of a single phase capacitor run motor please.

Thanks,

Martin P

John Rudd14/12/2018 10:54:43
1365 forum posts
58 photos

swap the two ends over on the main winding...

Edited By John Rudd on 14/12/2018 10:59:22

John Haine14/12/2018 11:06:35
2539 forum posts
132 photos

Or indeed the other winding, or use this approach...

image.jpeg

John Haine14/12/2018 11:08:08
2539 forum posts
132 photos

The above is the recommended Parvalux circuit to reverse I think the SD13 motor as used on the Quorn. W1 and W2 need to be identical for it to work properly. Somewhere on this forum I gave some analysis and measurements on the SD13 to show how it works.

Simon Williams 314/12/2018 12:05:34
386 forum posts
65 photos

Sometimes you can do a mechanical swap by taking the rotor out of the stator, and replacing it back to front, then fitting the two end bells opposite way round. I did this for a motor where the wiring wasn't accessible though it does rely on the rotor having the same size and type of bearings both ends.

Season's Greetings

Simon

Howard Lewis14/12/2018 14:59:07
2029 forum posts
2 photos

A number of solutions, depending on what you want as a final outcome.

 

If merely to reverse the direction of rotation of the driven item.

1) Turn the motor end for end, assuming that there is enough space.

2) As already suggested,dismantle and reassemble with the rotor installed the other way round

3) Modify the connections, to the windings, as shown.

If wanted as being capable of running in either direction, at will, (possibly to drive a lathe mill) then the ability to change the connections to windings needs to be by some form of changeover switch, such as the old fashioned Dewhurst Drum Switch .

In this day and age, H & S would want some form of No Volt Release switch in the circuit, for safety in the event of a temporary mains failure.

Howard

Edited By Howard Lewis on 14/12/2018 14:59:55

John Haine14/12/2018 15:00:28
2539 forum posts
132 photos

Stricly that amounts to mounting the stator back to front, leaving the rotor the same. Since the rotor has rotational symmetry, rotating it end for end has no effect. Swapping the stator would only work in an existing machine if the stator is symmetrical about the axis perpendicular to rotation, otherwise the ends of the shaft will be in the wrong axial position.

john fletcher 114/12/2018 16:22:16
505 forum posts

Do as John Rudd has said,however it's not always obvious which is the run winding. To locate the run winding carefully mark all wires before disturbing any of them, possibly take a photo with your phone.If you have an ohmmeter disconnect one of the A wires ( assuming the motor is an old one made in UK) and locate the other end, then reverse the pair. The run winding will have the lowest resistance and thicker wire. John

larry phelan 114/12/2018 16:43:16
433 forum posts
11 photos

Hi Martin,,

At the risk of Hijacking your thread,could I ask a question of the other Members?

I have a small 1/4HP motor,made by Hoover,single phase,no cap,very smooth running and quiet.

So far,so good ! Problem is that it cannot make up its mind which way it wants to run,no kidding !

Switch on to-day,it goes one way,tomorrow ? who knows,could be either way.

This is less than helpful,to put it mildly.

Anyone got any ideas how to help it on its way [one way or the other ]

IT,S 1425 REVS so a useful item .I had in mind to use it for a disc sander,but as it is,it would make life interesting !indecision

Emgee14/12/2018 16:54:25
1110 forum posts
200 photos

Martin

Do as John Haine suggests, the switch used is a single pole double throw (SPDT), best to get one with a centre OFF position.

The power in goes to the centre switch terminal and wires from the outer 2 terminals connect to the capacitor leads/windings ends.

All the switch does is put the live power to 1 or other side of the capacitor, this is as John says the recommended method of switching/reversing Parvalux capacitor start and run fractional horse power motors.

To change direction of a single phase induction motor with start and run windings reverse the ends of the start winding, this will normally be connected through a centrifugal switch.

Emgee

John Rudd14/12/2018 17:30:01
1365 forum posts
58 photos
Posted by Emgee on 14/12/2018 16:54:25:

Martin

All the switch does is put the live power to 1 or other side of the capacitor, this is as John says the recommended method of switching/reversing Parvalux capacitor start and run fractional horse power motors.

To change direction of a single phase induction motor with start and run windings reverse the ends of the start winding, this will normally be connected through a centrifugal switch.

Emgee

The theory is good as long as the two windings have the same characteristics, i.e the same impedance/wire gauge/ number of turns...

john fletcher 114/12/2018 18:09:59
505 forum posts

Hello Larry I've sent you a Pm regarding your motor. John

larry phelan 114/12/2018 20:00:28
433 forum posts
11 photos

Thanks John,

Just got that message now. Will check that out tomorrow,as you say,they are a nice little motor.

Again,many thanks.smiley

Phil Whitley14/12/2018 20:46:22
839 forum posts
105 photos

to reverse a single phase motor, be it capacitor start, or capacitor run, or both, with or without centrifugal switch, you reverse the polarity (swap over the connections) on the START winding, changing the polarity of the run winding will have no effect, as a single phase motor will always run in the direction it is started in. The start winding , measured with a multimeter, will have a higher resistance than the run winding.

Emgee14/12/2018 22:42:55
1110 forum posts
200 photos
Posted by John Rudd on 14/12/2018 17:30:01:
Posted by Emgee on 14/12/2018 16:54:25:

Martin

All the switch does is put the live power to 1 or other side of the capacitor, this is as John says the recommended method of switching/reversing Parvalux capacitor start and run fractional horse power motors.

To change direction of a single phase induction motor with start and run windings reverse the ends of the start winding, this will normally be connected through a centrifugal switch.

Emgee

The theory is good as long as the two windings have the same characteristics, i.e the same impedance/wire gauge/ number of turns...

John, that's why I also stated the Parvalux example used in John's sketch.

Emgee

John Rudd15/12/2018 07:30:41
1365 forum posts
58 photos

Emgee, my apologies, I dont s'pose many folk would realise that Parvalux motors can be treat that way, nor would they necessarily know the attributes of start run windings...blush

Ady115/12/2018 08:02:14
avatar
3463 forum posts
513 photos

Got an old AEI thread here

I presume if you run the two wires out to a dewhurst type switch and back in to C and D you can have both directions on tap

Edited By Ady1 on 15/12/2018 08:03:13

Emgee15/12/2018 09:53:56
1110 forum posts
200 photos

Hi John, you were correct to point to checking windings resistances to establish type of motor, the method suggested for Parvalux will clearly not suit differently wound motors.

martin perman15/12/2018 12:35:49
avatar
1587 forum posts
66 photos

Thank you all,

When the temperature goes slightly positive, maybe tomorrow, I will go and have a play.

Martin P

Neil Wyatt15/12/2018 13:06:19
avatar
Moderator
16066 forum posts
675 photos
73 articles
Posted by John Haine on 14/12/2018 11:06:35:

Or indeed the other winding, or use this approach...

image.jpeg

This only works with symmetrical windings, otherwise the smaller winding ends up doing the work.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
ChesterUK
Warco
Eccentric Engineering
TRANSWAVE Converters
Ausee.com.au
Eccentric July 5 2018
Allendale Electronics
emcomachinetools
Sarik
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest