Motor Runs Wrong Rotation

Well, Guv, it sounds like the neutral isn't connected. Have another butchers at it, and the supply wiring, and get back to us. <Cough>

Thanks but the neutral is connected....

Done a continuity check across the run winding yet from the live terminal to neutral? What is it in ohms?

<Splutter>

Ah! The other thing it could be is the neutral and the live links being correct for the start winding and wrong for the run winding. <Splutter>

have you checked if the rotation way of the motor is the same with the rotation way of the pump? make sure that it is! if it is not the motor is stopped because it has protections on high current and your pump is returning the fluid back in the main pipe.

Running the pump backwards will produce less demand on the motor, not more.

The fluid will still be expelled from the outlet, but at a reduced rate.

a single phase motor is running in the designed way- on the right or on the left. if this single phase motor can run in both ways it should have a changing rotation device (mechanical or electrical). if not, you cannot change that without making changes in the motor. you should verify the connection between the motor and the pump, maybe is a wrong connection between them.

Yeah. Astrid says it runs for a little while in the wrong direction, and then stops. Which means that the start winding and its cut-off switch is sweet, and the run winding isn't. I've had a bet with Dodgy Dave in Aveley, and my money is now on the run winding being open-circuit. And if it isn't, well, I'll get Dodgy Dave back. You''ll see. <Wheeze, cough>

Change the capacitor's polarity. Motor will start running in opposite direction.

NO! AC motor...

Yes, I know. It is Single Phase AC motors. DC motors doesn't use capacitor.

Just do it, you will get reverse rotation

Hi Astrid,

Need a little more info, you mentioned capacitor start, so there could possibly be a centrifigal switch that disconnects the start winding/capacitor once it is up to speed. The springs maybe weak or not there, I have used rubber bands in the past as a temporary fix. If this is fine, then check the capacitor, using an ohmmeter to do a simple check. It should initially have low resistance and the increase to a higher resistance as it charges up, do this disconnected.

Check out the windings, possibly you will have two sets of windings, one should be in series with the capacitor and the other should be straight across L-N.

Also one easy and simple check is to smell the motors terminal box, a pungent odour could mean it is burnt out.

Regards,

Trevor.

Did someone open the motor and mounted the stator turned 180° ?

This also changes the rotation of the motor......

Not with start capacitor/winding centrifugal switch in one end.

Has poster advised motor stopped due to thermal O/L trip actuating ?? is this because it cannot come up to speed?? faulty start winding??

On a single phase capacitor start motor, you reverse the motor direction by reversing the wires coming off the capacitor.

Kyoto,

You are right. Swapping the in-end connection points of a winding will change the relative direction of a starting torque in a single-phase (induction) machine, created by the 2 windings (main winding and auxilliary (capacitor) winding).

The characteristics of the machine may not be absolutely the same in the 2 directions if it has been designed (optimized) with a preferred rotation direction (CW or CCW), but it will turn in the opposite direction.

I hope I didn't mis-lead; reversing the connections on the starting winding is what I meant to say and the capactor is in series with that winding through a centrifugal switch. Just swapping the cap leads won't do it.

Kyoto,

Yes, this is correct. The reverse can be done only if the 4 terminations of the 2 windings are accessible. If (for instance) the input termination of the main winding is connected to the input termination of the auxilliary (in series with the contrifugal switch and capacitor) winding but is not accessible at the terminal box, the direction cannot be reversed, unless the motor is disassembled to gain access to the connection.

I said same thing in post #11

People, people, people...

So many of you are focused only on the reversing issue. He has 3 conditions going on here:

"Motor runs wrong rotation, and runs only short period but not at synchronous speed and then stops."

My original assessment of a defective start switch or capacitor is the only thing that fits this scenario.

Sorry, overlooked that little tidbit. You are probably correct about the switch. If the switch doesn't cut out the starting winding, the motor will not come up to speed and will eventually trip out on overcurrent. If the cap was bad the motor wouldn't start.

ha i hav the solution but i saw that when i was a little one.... i am doing my mech...

just change the connection on any parellel connection of neutral to main and main to neutral... i think it will work i saw it on my uncle garden.......

ha i am a mech student but i know the solution i heard it on my younger age... just change the line on a parallel connection of neutral to main and main to neutral.....i saw it on my uncle garden.....

Jeez, I give up...

Guess what it means

my fan in my bedroom ( as well as the Tube light too) is with 3 way switch ie you can switch on.off from the door as well from bed .

So this means that half the times (statistically) it will rotate forward and other half backwards. Also may be the tube light will give away light as well as suck away light ?

OK i withdraw the Tubelight portion.

But the fan is definitely a single phase Induction motor.

The AC too ? so the AC can be used as room heater by changing the switch (the direction of air flow reversed)

Don't give up my friend.

The poor guy has not understood what is AC !. (Post #22).

The in universe two things are abundant..... Helium and Stupidity.

Your post suggest that its a cap start motor, not cap run cap start.Just verify if there is centrifugal switch, if yes that validate this.

It seams to me that you fixed cap on main winding, where as it should have been in series with starting winding.It will not only reverse the direction of rotation but its will not let the motor run at full speed, which consequentially will not allow centrifugal switch to trip, and finally over heating of winding and TOP tripping.

I'll make easy for you. I had a blower motor on my furnace that was not running right. It was a 115 volt single phase, capacitor start. I replaced it. When I had the old one on the bench to check it out, every once in a while it would run backwards for no reason. It explained why it was taking a long time to cool my house at times (the blower was running backward). Turns out it was a bad winding in the motor. It did this with the capacitor connected and withoutout the capacitor

Guest,

When a single phase motor with a starting capacitor winding turns (for instance) 10 times CW and 3 times CCW, it means that the starting winding is not working as it should: it is not connected in parallel to the main winding every time (due to different reasons: bad contact on circuit, centrifugal switch temporary blocked in open position, ...).

The contact + switch may have worked in several cases providing the necessary connection, when the motor turned in the right direction (CW), while when the connection was interrupted, there was no torque to initiate rotation in the other direction (CCW). In this case, the only explanation that I see for turning CCW would be that the air flow turned the fan blades (and with them the motor rotor) in the CCW direction. When you closed the starting switch, that initial CCW rotation determined the direction of the starting torque (of the main winding), and the motor turned CCW.

Definitely in this case the auxilliary winding (capacitor) has to remain disconnected, otherwise there would be 2 opposite torques and (probably) the motor would reverse its direction.

With a hardwired connection and the 2 windings, a motor cannot turn in one direction a couple of times and later, at a later start, in the other direction.

When you mention " a bad winding in the motor" what exactly was there ? A motor designed to work with a starting capacitor cannot start at all without capacitor, unless it is (externally) turned in one or the other direction, but, as mentioned before, the other winding has to remain not connected.

I can't explain how or why it decided to change direction. After seeing it happen on my bench I took it to a motor shop I use for large industrial motors and they observed the same thing. Put power to the motor, it runs in one one direction. Take power away and wait for motor to come to complete stop and put power back. Repeat and every once in a while in runs in opposite direction. They tried with and without capacitor as I did. They said same thing. Motor should not start without the capacitor but it did. They asked me to leave motor so the could go over it and "play" with to see what is going on. The shop called a few days later and all they found was what they would call was a 'bad winding" , would not elaborate any further. One thing I have learned since my early years from high school electrical theory teacher is that with anything is possible with electric equipment. I have seen many things on my job happen that I was told cannot/should not happen happen in theory but in the field do happen. I now have the motor back and it is used in our HVAC division to show new techs that they should check everything on a system and not ignore the unusaul.

Well, the M in EMF stands for magic so there you go.