Introduction to Autotransformer Starter
An autotransformer starter is an electrical device used to start and control the speed of induction motors. It uses a single winding for both the starting and running of the motor. The autotransformer starter is composed of a transformer that provides a reduced voltage to the motor during starting, and the voltage is gradually increased during the run-up period. The autotransformer starter is a popular choice because it is cheaper than other starters and is suitable for motors with low inrush current.
Working Principle of Autotransformer Starter
The autotransformer starter works on the principle of voltage transformation. The autotransformer has a primary winding and a secondary winding. The primary winding is connected to the supply voltage, while the secondary winding is connected to the motor. During starting, the motor is connected to the autotransformer’s tapping, which is designed to provide a lower voltage. As the motor accelerates towards the full speed, the autotransformer starter gradually increases the voltage supplied to the motor. This gradual voltage increase avoids a sudden surge of current, which can damage the motor’s windings.
Advantages and Disadvantages of Autotransformer Starter
One of the significant advantages of the autotransformer starter is its cost-effectiveness. It is cheaper than other starters like star-delta starters and soft starters. Additionally, it also reduces the inrush current, which helps in preventing damage to the motor, transformer, and electrical cables. However, it has some disadvantages as well. The motor starting torque is lower than that of other starters, and it requires a substantial amount of space due to its design.
Example Application of Autotransformer Starter
The autotransformer starter is widely used in industries such as paper mills, cement plants, and petrochemical industries. In paper mills, it is used to start the paper machine’s motor, which is a large induction motor. In cement plants, it is used to control the speed of the cement mill’s motor. In petrochemical industries, it is used to start and control the speed of the compressor motor. The autotransformer starter’s application depends on the motor’s size, capacity, and operating conditions.
In conclusion, the autotransformer starter is a cost-effective and reliable device used to start and control the speed of induction motors. Its working principle is based on voltage transformation, and it has both advantages and disadvantages. It finds its application in various industries that utilize large induction motors.
