3 Phase Motor Parts—An Introductory Guide

Three-phase electric motors have a robust construction with different parts and working mechanism. These days, 3-phase ac induction motors are widely used in various industrial and commercial sectors due to their high speed and torque. Understanding different parts of 3 phase motor are essential to choosing the right fit for your application. Xinnuo Motor 0ffers a wide range of three-phase motors varying from 1500rpm-3000rpm.

Figure 1 3 phase motor parts

Figure 1: 3 phase motor parts

 In this introductory guide, we will discuss 3 phase motor parts and their functions. 

3 phase motor parts

Three-phase motors are famous because of their robust and reliable construction. Let’s understand 3 phase motor parts closely;


In 3 phase motors parts, the stator is the most integral component. It is the stationary part that influences the rotor to move in the direction of magnetic fields. This part of 3 phase motor further has the following sub-divisions;

  • Core:

Inside the stator, the laminated structure is present, which is known as the stator core. The stator core has paired slots depending on the number of poles of the electric motor. Some motors have 2 poles and 3 slots or 3 poles and 4 slots, etc. The speed of the motor is inversely proportional to the number of poles. If the number of poles is greater, the speed will be less and vice versa. 

  • Stator frame:

The outer covering of the stator is called the stator frame. The stator frame is made up of high-grade material and 100% stainless steel to protect internal parts. It also ensures long life and durability. 

  • Stator winding:

The stator winding generates magnetic fields in the stator. The three phases get excited when connected to the power supply and start producing magnetic fields. The stator windings are insulated and resistive to ensure protection in unfavorable conditions. 


Rotor is another important component in parts of 3 phase motor. The moving part that rotates in the direction of magnetic fields is called a rotor. The rotor of three phase motors carries the current to move the shaft. The three phase motor is further classified into two major categories based on rotor structure;

  • Slip ring or wound-type: 

The wound-type rotor generally consists of the slotted armature and slip rings. These motors provide high and constant starting torque; therefore, these motors are widely used in heavy load industries because it allows external resistance to reduce initial current. 

Figure 2 Rotor of Slip-ring induction motor

Figure 2: Rotor of slip-ring induction motor

  • Squirrel cage motor rotor: 

The squirrel cage motor is the most widely used 3-phase induction motor due to its simple cage rotor construction. The cage-type rotor comprises aluminum or copper bars fixed inside the slots. This type of three-phase motor is used for low-grade commercial and domestic purposes. 

Figure 3 Rotor of Squirrel Cage Induction Motor

Figure 3: Rotor of squirrel cage induction motor 

Terminal box:

The terminal box is also prominent in 3 phase motor parts. The terminal box provides a three-phase power supply through an external electrical supply. The stator windings are connected to the terminal box via delta or star connection. 


For heat dissipation and cooling, a fan is considered a significant part of 3 phase induction motors. It maintains the temperature and cools down other internal parts of 3 phase induction motor

Xinnuo Motor delivers standard quality OEM motors, single-phase electric motors, and industrial motors globally. 


Understanding 3 phase motor parts give you a broad idea of its working mechanism, load capacity, and applications. All parts of 3 phase induction motors contribute to providing effortless experience and precision. These motors are designed specially to provide high torque and functionality at an affordable price. You can contact us for a free quotation and inquiries. Our customer support operates uninterrupted to address your concerns. 

Frequently asked questions-3 phase motor parts

1. What is a 3 phase motor?

A three phase induction motor is an AC motor with impressive features. Three-phase motors are self-starting, efficient, and durable industrial motors. These motors work on the principle of electromagnetism and do not demand capacitors or an external power supply for initial rotations. These motors provide 1.5x more power than single-phase motors. However, it is important to understand 3 phase motor parts, working principles, and application before purchasing. 

2. How much do 3 phase motor parts cost?

The parts of 3 phase induction motors are made with 100% copper coil and stainless steel to ensure long life. These motors are a bit more expensive than single-phase motors because of 3 phase motor parts and functionality. The cost of three phase induction motor parts varies by multiple parameters such as voltage range, frequency, rpm, and construction type. 

3. What moving parts wear out in 3-phase induction motors?

The moving parts of 3 phase induction motor that wear out are bearings and slip rings. The 3-phase induction motor has two bearings for rotation of the shaft. Sometimes, the bearings wear out due to low maintenance, over-loading, and installation errors. Moreover, in slip-ring inductions motors, parts of 3 phase motor that wear out are slip rings. 

Scroll to Top