How to change rotation on a single phase motor

how to change rotation on a single phase motor

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Jan 03,  · To change direction of rotation, swap 5 & 8. I wired the 12/4 so that black fed #1; red fed #4 and white (switched wire) fed #5. Just like the original motor. The new motor works just fine. Jun 12,  · Once started, a single phase induction motor will happily run in either direction. To reverse it, we need to change the direction of the rotating magnetic field produced by the main and starter windings. And this can be accomplished by reversing the polarity of .

Mogor first and most important step in changing motor rotation is to lock out the motor. This is done by disconnecting the motor at the nearest power source and locking that connection open. It is important to write all information on the lockout tag and include it with the lock on the disconnect. The key to the lock should not be In any hands other than yours. Next open the cover on the motor to access the motor leads.

Verify motor is locked how to utilise space under the stairs by checking for voltage with a meter. Check between all power wires and between power wires and ground. If no voltage is present proceed with the next step. Then, determine if the motor is 3 phase or DC. The nameplate on the motor will state what it is. If the nameplate is to worn to read or missing, count the number of wires. An AC motor tp have three phases so there will be three power wires.

DC motors only have a positive and negative power wire. If the motor is 3 phase determine the power wires. These should be labeled T1, T2, and T3.

Any other wires are for changing motor voltage and should not be touched. Swap any two of the power wires and the motor will change rotation. Again, be sure not to swap any wires other than these.

After switching the wires replace the cover and return power the the motor. It is important to have someone stand by the motor and verify it is turning the correct way as the disconnect is turned back on. Did you make this project? Share it rotatiion us! I Made It! Reply Upvote.

Reversing a split phase motor

In order to change the rotation of the single phase induction motor, the connection to one of the stator windings (starting winding and main winding) is reversed. But later we cut the starting winding,so how is it possible to reverse the direction of rotation of the single phase induction winding? The first and most important step in changing motor rotation is to lock out the motor. This is done by disconnecting the motor at the nearest power source and locking that connection open. It is important to write all information on the lockout tag and include it with the lock on the disconnect. To complete a single phase motor direction change, you will need to motors go in forward and reverse depending on their wiring and the resulting magnetic field. ask that they not flip any breakers or switches until you are finished. To reverse rotation on a single phase capacitor start motor, you will. Reversing single phase induction motors.

I didn't cover how induction motors start in any detail earlier because that's an extensive topic on its own. The rotor of an induction motor is essentially a permeable iron core with an aluminium short circuit winding cast in place. You can see the aluminium on both ends of the rotor. The aluminium also goes through lengthwise holes in the rotor to make a "squirrel cage" type short circuit winding.

You can barely see lines, at a slight angle on the rotor where the windings pass through. The short circuit winding causes the rotor to resist rapid changes in magnetic fields, so if it's subjected to a spinning magnetic field, it will try to follow it.

But for single phase AC motors, the magnetic field only alternates back and forth. Some trickery is needed to create a rotating field. Reversing a split phase motor In this split phase motor, the main winding label 'M' is connected directly to 60 Hz AC power, while the other winding label 'O' is wired in series with a capacitor C.

The interaction between the inductance of the motor windings and the capacitor's capacitance causes that winding to be about 90 degrees out of phase with the main winding. With the main winding creating a magnetic field that alternates vertically, and the other winding creating a magnetic field that alternates horizontally but out of phase, the sum of these is a spinning magnetic field.

The rotor tries to follow it, causing it to spin. Reversing the motor is simply a matter of moving the power connection so that the other winding is directly on AC. Essentially, moving one side of the power connection from A to B , causing winding O to be the main winding and winding M to be the phase shifted one.

Check that the resistance of the two windings is the same first. If the windings are not the same resistance, you can still reverse it by reversing the polarity of one of the windings, provided that the windigs are not tied together inside the motor as in, more than three wires coming out from the windings.

The windings are spread across many slots in the motor's stator C. That way, there is less of an abrupt change from one pole to the next.

This makes for a smoother magnetic field, which makes for a quieter, more efficient motor. This motor has a thick main winding M , plus a starter winding made of thinner wire S.

The main winding creates a horizontal magnetic field, while the starter winding creates a vertical one. This starter winding is in series with a capacitor C , and a centrifugal switch S. In this motor, the starter capacitor is mounted inside the main housing.

More typically, the starter capacitor is mounted on top of the housing under a metal dome. The centrifugal switch S is mounted to the back plate and is activated by a disk P that pushes against a tab on the switch just left of the S in the photo. Removing the rotor and looking at the disk, you can see two metal tabs. When the motor spins, centrifugal force pushes these outwards, which in turn pulls the disk back. This releases the plastic tab on the switch, causing the switch to open and the starter winding to be disconnected.

The disk pulls back far enough that it's no longer in contact with the tab, minimizing friction and wear. It's a clever way to activate a switch based on centrifugal force without the need for the switch itself to spin.

The centrifugal switch arrangement makes a distinct "click" when it resets after the motor is shut off. The click of the switch engaging as it starts up is much harder to discern.

If the starter winding helps the motor start, it would surely help the motor run as well. So why not just leave the starter winding connected? Well, the whole phase shift thing is not that elegant. The size of capacitor you need very much depends on the motor's load.

To start the motor quickly, you need a larger capacitance than you would for efficient continuous operation. Also, the capacitor is an electrolytic capacitor, and isn't designed for continuous load. And because the starter winding is only used briefly, so it's made of thinner wire to save money, because copper is expensive. There are some motors that use a big capacitor for starting and a smaller capacitor for continuous operation.

Such motors often have two externally mounted capacitors C , as seen on this one in my table saw. These motors are called "capacitor start capacitor run" motors. Capacitor start capacitor run motors are typically more than one horsepower. This one is 1. Motors can be made cheaper by replacing ther capacitor with a resistor.

Though typically no separate resistor is added. Instead, the starter winding is made from thinner cheaper copper wire so it has more resistance in the winding itself. This results in much less phase shift than with a capacitor, but enough to get the motor running. The windings of the motor essentially form an inductor, and when an AC sine wave as in, AC power is applied to an inductor, the current lags the voltage by 90 degrees. And the magnetic field is strictly a function of current.

For a resistor, the current is in phase with the voltage. If we had a large resistance and small inductance in series, the voltage drop, and current would be largely determined by the resistor. So the current and magnetic field would be largely in phase with the applied voltage. With current in the main winding lagging by 90 degrees, we would have a degree difference between the two, but the starter winding would be extremely inefficient. In reality, the compromise is for much less of a phase shift and more power.

It's enough to get the motor running. Regardless, the starter on these motors is quite inefficient, but it doesn't matter much once the motor is running. If you are not familiar with analog electronics, the above explanation is probably inadequate, and you may want to read up more on induction motors if you don't understand it. With induction motors, the only things that wear out are the bearings, the starter switch and the capacitor.

With no capacitor, there's one less thing to fail. Reversing a capacitor start motor. You could also reverse the motor by reversing the main winding same effect. If you were to switch the main and starter windings, as one does with a split phase motor, the motor will also reverse. However, it will not run at full power and is also likely to burn out. The starter winding is not suitable for continuous operation.

If you look at the previous pictures of this motor, you can see there are only three wires red, yellow and blue coming out from the windings. One end of the main and starter windings is connected together right on the windings.

To reverse the starter winding, I'd have to break that connection inside the windings and bring out the other end of the starter winding. But I really can't get at it because of the way it's inside the motor. I'd have to cut a hole in the enclosure to even get at the point where they are tied together. It's not that this motor can't be reversed, just that, as a cost saving measure, they made reversing it more difficult than is worth the trouble.

See also: How AC induction motors work. Switching motors between and volts. Where do you get your motors from? Figuring out a mystery motor and building a starting switch. Homemade benchtop power supply. Building a dust collector blower. Photographing airborne dust. Are link belts worth it?

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