What Is Single Phase Motor?—A Detailed Overview

Are you a beginner and want to understand “what is single phase motor”? You are at the right place! Single phase electric motors have dominated the low-grade commercial industries with their impressive features and affordability. According to the latest report, global electric motor share due to their low cost and wide applications. 

Single phase electric motors are highly reliable and have low energy consumption. Xinnuo motor is the leading electric motor manufacturer in China that offer premium quality single-phase motors at an affordable price.

Figure 1 Single Phase Motor

Figure 1: Single phase motor

This article will provide you handful of relevant information and noteworthy features of single-phase motors.  

Let’s begin with it.

What is single phase motor? 

With non-complex structure and extended life, single-phase motors are the perfect example of “simple yet effective.” Single phase motors are defined as electric motors that operate on single phase power supply. Single phase electric motors are suitable for domestic and low-volume industrial purposes due to their robust construction and low maintenance rate. 

Since single-phase motors run on single-phase power, there are comparatively less efficient than three-phase motors. However, single-phase motors are the perfect choice for machines that require low PF ratings and torque. 

Xinnuo Motor also offers a wide range of three-phase motors, industrial motors, and explosion-proof motors. 

Types of single-phase motors: 

If you want to comprehend what is single phase motor, you need to understand its different types. Single phase motors are classified into two primary categories due to the difference between their working mechanisms;

  • Single phase Synchronous Motors
  • Single-phase Asynchronous Motors 

The synchronous and asynchronous motors are similar in construction. The only difference between these two categories is the speed of the rotor. 

Parts of single phase motor: 

As we have discussed above single phase motors have simple construction, let’s discover their various parts to comprehensively understand what is single phase motor and how it works.


Figure 2 Rotor of Single phase motor

Figure 2: Rotor of single phase motor

The rotor is a single phase motor comprises of the squirrel cage structure, which rotates around the stator winding to provide the rotating magnetic field. Copper and aluminum bars are placed inside the periphery of the single phase rotor for mechanical strength. 


The stator of single phase motor consists of two winding; main and auxiliary winding. The current flow through the main winding, whereas auxiliary winding generates an initial rotatory field and becomes electrically offset afterward. If the speed of the rotor and rotating magnetic fields is not synchronized, the motor is termed as an asynchronous motor. 

Want to know more? Check out our latest article on single phase asynchronous motors for comprehensive knowledge. 


Due to high thermal and mechanical stress, a fan is used to maintain the internal temperature of the single phase motor. A fan is enclosed in the motor for heat dissipation to stabilize the temperature gradient of the motor. 

Why do single phase motors require capacitors?

We usually get, what is single phase motor with a capacitor? Let’s figure out the functionality of capacitor-driven single phase motors.

Single-phase motors depend on capacitors and an external power supply for initial rotations. These motors are not self-starting; thus, they cannot generate constant rotation. These motors demand an auxiliary power source because of the low power factor. A capacitor is a perfect solution to increase the working efficiency and PF rating of single-phase electric motors.

Single phase electric motors are classified into three categories based on the capacitor used in them. Let’s find out; 

  •  Capacitor start:

Figure 3 Single-phase Motor Circuit Diagram with Start Capacitor

Figure 3: Single-phase motor circuit diagram with start capacitor 

A capacitor-start is used in a single phase motor to generate an initial rotatory field. A capacitor is connected to the auxiliary winding in motor wiring. Once the motor gains a certain speed, it is disconnected by the centrifugal switch

  • Capacitor run:

A capacitor run is connected to the main winding to provide constant rotation throughout the operation. Capacitor-run does not provide starting torque to the single phase motor. 

  • Capacitor-start and run: 

Capacitor start/run is a combination of a high-value starting capacitor and a low run capacitor. Starting capacitor generates starting torque, and a low-value capacitor minimizes the pulsating torque at full load. 

What Is Single Phase Motor-Conclusion:

If you want an affordable motor that operates flawlessly under unfavorable conditions, a single phase motor is what you are looking for. These motors are designed for home appliances and low-grade industries providing low PF and reliable performance. For further information and free quotation, contact us

What Is Single Phase Motor-FAQs: 

What is single phase motor capacitor wiring diagram

Single phase motor wiring with capacitor is simple. Single phase motor connection is developed with the capacitors via main and auxiliary winding.

 It looks something like this;

Figure 4 Capacitor connection diagram

Figure 4: Capacitor connection diagram

What is single phase motor starter? What is their function? 

Single phase motors use starters to ensure safe motor operation in hazardous conditions. A starter is a device used to protect the motor from over-current. It safely starts, stops, and reverses the motors. 

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