1 phase induction motors are widely used in many applications due to their simplicity, cost-effectiveness, and simple operation.
They are commonly used where a three-phase power supply is not available or practical. In this article, we will explore the construction, working principle and application.
Working Principle of 1 Phase Induction Motor
The working principle of a single-phase induction motor is based on Faraday’s law of electromagnetic induction and double-field revolving theory
Applying a 1 phase AC supply to the stator winding produces a pulsating magnetic field, which is not a rotating magnetic field.
Starting of a Single Phase Induction Motor
A single-phase induction motor is not self-starting and does not have a rotating magnetic field like a multi-phase motor.
To make it self-starting, it can be temporarily converted into a two-phase motor while starting.
This can be done using a split phase starting technique where the motor has two windings, a run winding, and a start winding with a capacitor in series with the start winding.
Hence emf is induced into the rotor conductor by induction due to this emf current will start flowing into rotor bars which are short circuited at both ends. This rotor current develope rotor flux. The desire torque required for rotation of rotor is created by this two fluxes.
Construction of 1 Phase Induction Motor
The 1 Phase Induction Motor is constructed with two major parts – stator and rotor.
The stator is the stationary part of the 1 phase motor and comprises several thin laminated sheets.
These sheets are stacked together to reduce power loss due to eddy currents.
On the stator, there are numerous slots where the winding coils are placed.
These winding coils produce a magnetic field when the alternating current passes through them.
These windings are isolated from each other and form two different groups of windings – main winding and auxiliary winding.
The rotor of a single-phase induction motor is of the squirrel cage type.
It consists of conductive bars (usually made of aluminum or copper) placed in slots on the periphery of the rotor.
The bars are short-circuited at both ends by end rings. This arrangement forms a complete closed circuit resembling a cage, hence the name “squirrel cage rotor.”
It behaves like a short-circuited secondary of transformer, with the stator acting as the primary of this transformer.
Advantages of 1 Phase Induction Motors
Single-phase induction motors offer several advantages, making them suitable for a wide range of applications:
Simplicity: Single-phase induction motors are simple in construction, making them cost-effective and easy to maintain.
Cost-Effective: 1φ motors are generally less expensive to purchase and maintain compared to three-phase motors.
Reliability: 1φ Motors are known for their reliability and robustness, making them suitable for various applications.
Availability: Widely available in different sizes and power ratings, making them easily accessible for various requirements.
Suitability for Small Power Ratings: 1 phase induction motors are ideal for small power applications, such as household appliances, due to their efficiency and cost-effectiveness.
- 1φ motors Output is only 50% compared to 3 phase motor for the same hp and frame size.
- Efficiency is less
- Low power factor
- Low starting torque
Applications of 1 Phase Induction Motor
Now that we understand how a single-phase induction motor is built and how it works, let’s explore the many applications.
- One of the most prevalent uses of single-phase induction motors is within household appliances such as refrigerators, washing machines, dishwashers, fans, blowers, water pumps, and vacuum cleaners.
- 1 phase induction motors find application in agriculture. These motors are used in irrigation systems, crop thrashers, and other farm equipment due to their robust construction.
- 1 phase motor Used in Power saws, drills, and even the air compressor.
Single-phase induction motors are an essential part of our daily lives, powering various appliances and equipment. Their simplicity, cost-effectiveness, and reliability make them an ideal choice for small power applications. With various types and starting methods available, single-phase induction motors continue to play a crucial role in our modern world.