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How to reverse 1 and 3 phase motors direction

Hi, thank you for visiting this blog. In this article, we will discuss about a topic that is quite important, how to reverse 1 and 3 phase motors direction especially for those of us who have electrical equipment that uses a single-phase electric motor as its driving force.

How to reverse 1 and 3 phase motors direction

As we know, there are lots of electrical equipment in our homes that use a single-phase electric motor to operate. For example, water pumps, coconut grater machines, fans, air conditioners, washing machines, refrigerators, and others.

How to reverse 3 phase motor direction?

If the 3 phase electric motor consists of 3 coils, then the 1 phase electric motor consists of 2 coils. The first is the main coil and the second is the auxiliary coil.

In a 3 phase motor, to change the direction of rotation is done by reversing the RST cable source that is connected to the motor terminal.

In a single phase motor, changing the direction of rotation is done by reversing the source to the auxiliary coil or the main coil.

In a 3 phase motor, to get the motor rotation clockwise, for both star and delta connections, the standard connections to the motor terminals are as follows.

How to reverse 1 and 3 phase motors direction

To make it rotate counterclockwise, the connection will be like this.

How to reverse 1 and 3 phase motors direction

Yeah, to make it rotate counterclockwise, we just need to swap the positions of the R and S wires on the motor terminals.

How to reverse 1 phase motor direction?

Now what about single phase motors? As I mentioned above, a 1-phase motor consists of 2 coils, namely the main coil and the auxiliary coil.

In the auxiliary coil, there is a capacitor that will serve as the initial starting of the motor.

if there is no capacitor in the auxiliary contact, then the 1-phase electric motor will not be able to rotate when it is first turned on. He would just buzz.

The following is how to reverse the direction of rotation of a single phase motor.

How to reverse 1 and 3 phase motors direction

the schematic diagram above is the connection inside the electric motor, actually in the motor terminal box there are only 3 wires with red, yellow and black colors.

The wire colors for the main and auxiliary windings may differ on each motor, depending on the manufacturer that made the motor, but the point is the same.

the following is the actual connection of the motor terminals according to the schematic above.

Figure 1 on the motor terminal (Normal CW rotation)

Figure 2 on the motor terminal (CCW rotation)

Figure 3 on the motor terminal (CCW rotation)

As we can see in Figure 1 above, the power source to the U1 (main) and Z1 (auxiliary) coils is a phase (L) source, and U2 and Z2 get a neutral source. Connections like this will make the electric motor rotate clockwise.

While in Figure 2, we see that the U1 coil gets the source from the neutral and U2 from the line. While on the auxiliary coil, Z1 still gets a source from the line and Z2 from neutral. Because one of the coils, namely the main coil, gets the source in reverse from the example in figure 1, then in this condition, the motor will rotate in reverse (counterclockwise).

As for Figure 3, we see that the main coil gets its source from the same line as Figure 1, but differs in the auxiliary coil. This will make the 1 phase electric motor will also rotate in reverse (counterclockwise).

So, the conclusion is if we want to change the direction of rotation of a single phase electric motor, then we only need to change the source to one of the main coils or auxiliary coils.

What if we change both of them? It won't work because it's tantamount to having multiple pole positions and coil positions at once.

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