Author Topic: Motor rotation?  (Read 8160 times)

Offline PJW

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Motor rotation?
« on: March 05, 2016, 08:27:52 AM »
Hi, I have this little motor & it is running the wrong way. I have two items I need help with,
 (1) I need to reverse the rotation &
 (2) what switch do I need to make it run bi-directional.
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Offline PJW

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Re: Motor rotation?
« Reply #1 on: March 05, 2016, 08:30:39 AM »
I am a little worried about shorting the motor!

thanks
Peter
Old Guys Rule the Dark Side of the Shed!

Offline stevehuckss396

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Re: Motor rotation?
« Reply #2 on: March 05, 2016, 11:41:46 AM »
typically there is a name plate on the motor that shows of its reversiable and if so, the information to do it.

Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline PJW

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Re: Motor rotation?
« Reply #3 on: March 05, 2016, 12:15:21 PM »
there is no nameplate!
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Offline BaronJ

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Re: Motor rotation?
« Reply #4 on: March 05, 2016, 12:31:19 PM »
Hello Peter,

It is a bit difficult to see from your pictures, but generally those sort of motors are capacitor start and run.  They don't have a centrifugal switch used to disconnect the start winding. 

It is hard to be sure but the capacitor is connected to one leg of each winding and the other ends of the winding's are connected together and usually are the mains live terminal.  The mains neutral going to one side of the capacitor.  Moving the mains neutral to the other side of the capacitor should cause the motor to run the other way.

The caveat here is that both windings may not be the same value.  A rough check with an ohmmeter should show if the windings are similar or not.  If they measure within a few percent of each other, then I would suggest that they are the same.  Though often the two windings have wire of different sizes, which is a clue to the windings being different.  If this is the case then surgery is required to reverse the motor direction.

HTH.
Best Regards:  Baron.

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Offline Bluechip

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Re: Motor rotation?
« Reply #5 on: March 05, 2016, 01:42:32 PM »
What you appear to have is this.

As you need to get at both ends of the AUX winding you need to strip the motor and bring both ends out to use a DPDT switch. You also need it to be of the 'ON - OFF - ON' type, not a good idea to slam a motor from one end to t'other in an instance.

As Baron says, I doubt if it has a 'start' switch, but if you meter from X to Z [ disconnected of course] you will read the resistance of the RUN winding and metering from Y to Z will tell you what the AUX winding is. I suspect the RUN will be the lower of the two, usually is. [ This does assume the cap is OK and there is no start switch].

The switch appears to be some sort of 'No volt release' type?? Looks a bit relay-ish to me. Which complicates matters somewhat. What's on the other side of it? Start and stop buttons ??  :thinking:


The other way to reverse a motor is to is to swap the ends the RUN winding but you can't get at both ends of this either.

As Baron says, it's a surgery job,   :zap: and sometimes not very easy to get at the common point of the two windings.

Would be nice to know where the motor originates and if it's being 're-purposed' ??

EDIT .... 'C' is the capacitor ..  :old:

Dave
« Last Edit: March 05, 2016, 01:54:20 PM by Bluechip »

Offline Stuart

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Re: Motor rotation?
« Reply #6 on: March 05, 2016, 02:05:08 PM »
Nicely put Dave

With two years armature/stator winding when I did my time I will not comment on this because I would like to apply the mark 1 eyeball to it before passing judgement one wether it can or cannot be made to go backwards , the circuit Dave has posted will do the job fine

Digging in the winding has a high potential to cause it to be K for not working

Stuart
My aim is for a accurate part with a good finish

Offline Alyn Foundry

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Re: Motor rotation?
« Reply #7 on: March 05, 2016, 02:47:29 PM »
Hello Peter.

How many wires are coming out? I see 3 from your photo. Red, Blue and uncertain White?

Kind regards, Graham.

Offline PJW

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Re: Motor rotation?
« Reply #8 on: March 05, 2016, 02:57:07 PM »
Hi Dave, the motor used to be a table saw, the relay switch is as you thought an on/off switch.
I thought I would need an on -off-on switch but I dont know what a DPDT switch? I thought I would need something with a crossover so the capacitor would switch between the red & white with the blue as neutral or was I completely wrong,

Peter
Old Guys Rule the Dark Side of the Shed!

Offline PJW

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Re: Motor rotation?
« Reply #9 on: March 05, 2016, 02:58:57 PM »
yes there are three wires red white & blue
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Offline Alyn Foundry

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Re: Motor rotation?
« Reply #10 on: March 05, 2016, 03:04:38 PM »
Hello Peter.

Simply cross over the Red and White position, those Orange domes have a tapered thread internally and twist the connections together.

You should have a reversal of motor direction.

Kind regards, Graham.

Offline Don1966

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Re: Motor rotation?
« Reply #11 on: March 05, 2016, 03:33:33 PM »
I don't believe it's that simple Graham. I am not that firmiliar with European motors but when you have three leads the starting winding lead is brought out to tie the capacitor, so that's the third lead and the other end is tied to a common lead. When I did my myford motor connection mod I had to go internal to get the four leads. In the states we have dual voltage motors 120/240 and you only have 240 volt motors so in order to connect it to 120 I had to do a mod. My Myford motor modification is here.....http://www.modelenginemaker.com/index.php/topic,544.msg4409.html#msg4409

Don

Offline Bluechip

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Re: Motor rotation?
« Reply #12 on: March 05, 2016, 04:10:27 PM »
Don is right. It is not that simple. To reverse a motor you have to reverse the current through either the run winding OR the Aux. winding. To do this you need both ends of one or the other. I have done this many times and I don't know of an alternative.

It needs to be like MOTOR 2 piccy.

[1] The end of the AUX winding originally connected to white needs to be to blue.
[2] The end of the AUX winding originally connected to blue needs to be to white.


PJ does not have access to the red-ringed connection without getting into the motor.

DPDT is 'double pole - double throw'.

Bearing in mind you have high inrush current on a motor, this would probably be a suitable switch, but we would need to know just what that 'switch' fitted now does.  :ThumbsUp: 

http://cpc.farnell.com/apem/649nh-2/10a-toggle-plastic-dpdt-on-off/dp/SW02439

Dave
« Last Edit: March 05, 2016, 04:27:40 PM by Bluechip »

Offline Alyn Foundry

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Re: Motor rotation?
« Reply #13 on: March 05, 2016, 04:27:07 PM »
Hello Don and Dave.

I'm basing my post on the fact that to reverse a single phase motor you just need to alter the direction of one winding against the other. Blue is common so theoretically reversing the Red White should see current flowing in the opposite direction. The use of those thumb terminations might also be a clue.

Anyway for the sake of two minutes, time will tell. I'm quite old enough to eat " Humble pie " !!   :)

Kind regards, Graham.

Offline Bluechip

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Re: Motor rotation?
« Reply #14 on: March 05, 2016, 04:31:17 PM »
Hello Don and Dave.

I'm basing my post on the fact that to reverse a single phase motor you just need to alter the direction of one winding against the other. Blue is common so theoretically reversing the Red White should see current flowing in the opposite direction. The use of those thumb terminations might also be a clue.

Anyway for the sake of two minutes, time will tell. I'm quite old enough to eat " Humble pie " !!   :)

Kind regards, Graham.

Not quite sure which red & white ? If you swap the one direct to the RUN & the white to AUX you've not reversed one current with respect to the other and IF they are not the same wind you now have the reactance of the capacitor in series with a winding it was not designed for.

Quite true, but to 'flip' the connections you need both ends ..  :ThumbsUp:

Scruit connectors are used 'cos they are cheap ..  ;D

Dave
« Last Edit: March 05, 2016, 04:35:28 PM by Bluechip »

 

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