Introduction to Wound Rotor Induction Motor

A wound rotor induction motor, also known as a slip ring induction motor, is a type of electric motor that uses a wound rotor and a stator to induce current and produce rotation. The wound rotor induction motor is a popular choice for heavy machinery and industrial applications where variable speed control and smooth starting are required.

The wound rotor induction motor is similar to the squirrel cage induction motor in many respects, but it has a few key differences that make it suitable for certain tasks. The rotor consists of a series of wire coils that are connected to slip rings on the shaft. These slip rings allow the rotor windings to be connected to an external power source, which can be used to control the motor’s speed and torque.

Working Principle of Wound Rotor Induction Motor

The wound rotor induction motor works on the principle of electromagnetic induction. When an AC voltage is applied to the stator windings, it creates a rotating magnetic field that induces a current in the rotor windings. The current flows through the rotor windings and creates its own magnetic field, which interacts with the stator magnetic field and generates torque.

In a wound rotor induction motor, the rotor windings are connected to slip rings on the shaft. These slip rings allow an external resistance to be connected to the rotor windings, which can be used to control the motor’s speed and torque. The resistance can be adjusted to change the amount of current flowing through the rotor windings, which in turn changes the strength of the magnetic field and the amount of torque produced.

Advantages of Wound Rotor Induction Motor

One of the main advantages of the wound rotor induction motor is its ability to provide variable speed control and smooth starting. The external resistance connected to the rotor windings can be adjusted to control the motor’s speed and torque, allowing for precise control over the motor’s performance.

Another advantage of the wound rotor induction motor is its ability to handle high starting torque loads. The external resistance connected to the rotor windings can be adjusted to provide a high starting torque while limiting the current drawn from the power source.

Finally, the wound rotor induction motor is well-suited for applications that require frequent starts and stops or reversible operation. The external resistance connected to the rotor windings can be adjusted to provide smooth starting and stopping, and the motor can be easily reversed by swapping the connection of the slip rings.

Example Applications of Wound Rotor Induction Motor

The wound rotor induction motor is commonly used in heavy machinery and industrial applications where variable speed control, high starting torque, and smooth starting and stopping are required. Some common applications of the wound rotor induction motor include:

• Crane and hoist systems
• Elevators and escalators
• Mining equipment
• Steel rolling mills
• Large pumps and fans

In conclusion, the wound rotor induction motor is a versatile and reliable electric motor that offers precise speed control, high starting torque, and smooth starting and stopping. Its ability to handle heavy loads and frequent starts and stops makes it ideal for a wide range of industrial applications.