Some motors work better than others, depending on the application and type of machine. With that said, finding out how each work is vital. If you’re new to motors and everything about them, this information will help.
Firstly, there are single and three-phase motors. You don’t need a 3-phase motor if you deal with smaller equipment. However, if you have larger machines for lighting or refrigeration, three phase motors are perfect.
Here, you’ll discover all there is to know about single-phase motors. But first, what are they? And do you need a single phase or three input options to power your machines?
Why Call Motors Single Phase?
The term “single-phase” comes from the power input. Like most electric motors, these also contain rotors and stators. However, single-phase inputs have a single winding in the stator to carry an AC current. In addition, the rotors are simpler than other common motor designs.
The Types of Single-Phase Motors
From the explanation, these motors are known as single-phase because of the power input supply. The term has nothing to do with the stator, rotor, and starter arrangement. Unlike three-phase options, single-phase input motors need less maintenance. They are also more common, especially for uses needing less horsepower.
For rotation to occur, these motors have additional winding outside the stator coil. In this case, the starter winding uses a smaller diameter wire than that used in the stator for more resistance. The split-phase motors are more commonly used for:
- Driving ceiling fan blades
- Operating washing machine tubs
- Driving small pumps
- Running oil furnace blower motors
The starter winding (with higher power) gets the motor moving. Once it reaches the full speed of about 75% speed, the centrifugal switch switches to the less powerful coil, thus saving energy.
Shaded-pole Induction Motors
This is a single-phase type that does not rely on starters or windings to activate the motor. Instead, it is more simplistic and uses a rotor known as a squirrel cage. This motor has shade windings located at each corner of the stator.
The windings are not connected, but they generate currents by causing the magnetic field to go through the shaded portions. The shading coil leads to unequal distribution of forces (inductive) across the rotor. As a result, it creates a low torque and prompts movement and motor rotation.
Permanent-split Capacitor Motors
These are slightly different, as they have a permanent capacitor working with the starter winding. However, there’s no centrifugal switch. The capacitor works full time as the motor runs, producing less horsepower.
Nonetheless, permanent-split capacitor motors don’t need a starting mechanism, such as a switch or button. They are also more reliable, reversible and better than other single-phase options. These motors are excellent for use in:
- Air conditioners
- Refrigerator compre
- Office machinery
Capacitor Start Motors
In these motors, capacitors work with the additional winding, providing the difference in phase needed to start rotation. Capacitor start motors are similar to split-phase motors. However, they don’t use resistance to shift the starter phase. Instead, capacitor-start run motors use capacitance.
Once the motor hits a speed of 80% of the full speed, a centrifugal switch disconnects the start capacitor and moves to the run capacitor.
Applications for these motors include:
- Small conveyors
- Large blowers
- Machine tools
The Advantages of Single-phase Motors
Single phase motors have many advantages compared to other motors, such as the three-phase. Consider going single phase for the following reasons:
- They are less expensive to manufacture
- These motors need very little maintenance
- Repairs needed are minimal and easy to complete
- These motors last long
- Motor failure is due to application issues, not manufacturer defects
Although these motors are great, there are some disadvantages associated with their application. Some reports indicate overheating, failure to start and running slow. However, manufacturers are happy to sort out manufacturer issues, making them a good option for lighter and simpler applications.
There are enough single-phase options to choose from. Therefore, if you feel it’s the right option for use, find a reliable manufacturer and get the single-phase option. While other motors like the three-phase are good too, it might be a waste if you don’t need heavy applications.