Motor starters are the electrical devices used to run motors safely, as they can provide protection from overcurrent and low voltage and switch the power on and off automatically. They can also reverse the motor’s direction, which may be a useful feature in certain instances. The two main components of a motor starter include the electrical contractor (used for switching the power supply on and off), and the overload protection circuit (protects the motor from the overload conditions).
The Importance of Motor starters-
An induction motor’s starter winding may be connected to the 3-phase supply directly. The initial current input may be up to 7 times more than the full load current limit of the motor, and the surge may be harmful to the electrical equipment that is connected to the electricity supply. Overheating may also occur because of the long starting period. Hence the starters may provide for a safe starting of the motor. They may also protect against over/under loading. The starters are now available in different sizes to fit into the specific applications better.
Motor Starters Types and Varieties-
Some of the essential varieties and types of motor starters used by the induction motors are given below–
Direct On Line Starter- The smaller induction motors of power up to 10 kilowatts are run using this motor starter variety. The starter may offer benefits like cost-effectiveness and have a simple construction while not requiring any excess or extra space. However, the rush-in current and the starting torque here may be a bit high.
Star Delta Starter- Induction motors of power capacity: More than 10 kilowatts are run using the star-delta starters. They can reduce the starting torque (by around one third) and the starting current effectively. The starters are useful when the acceleration times are long, and they have a simple building and construction. However, the star-delta starters do require a greater number of wired connections, and their output torque is low.
Autotransformer Starters- The starter provides for better control and flexibility, as the users can start a motor at 80%, 65%, or 50% of the line voltage. After the motor reaches its appropriate speed, the starter will disconnect itself from the circuit automatically. The starter and method are used for the large machinery and is quite costly. The autotransformer motor starters offer benefits like high torque output and possess flexibility as well. However, they are expensive, and the equipment has a large size.
Soft Starters- The starter is used for the AC induction motors and can reduce voltage effectively. A soft starter may reduce the maintenance cost of the motors and extend their lifespan. The benefits of soft starters include a low cost and size, controlled acceleration, and improved efficiency. They are expensive, and heat dissipation may be associated with their use and deployment.
VFD starters- The starter is used for running and controlling the VFDs or the variable frequency drives. With the use of the starter, the speeds of the motor can be varied from 0 RPM to up to 120% of the full speed rating. A rectifier first converts the AC voltage into DC, and after smoothening, the DC voltage is converted back to AC. A VFD starter offers benefits like low inrush current, smooth acceleration, speed control, and even de-acceleration, among others. However, problems like heat dissipation and high cost may be its disadvantages.
Talking to a leading industrial panel manufacturer will help industries procure the right panels and enclosures for their motors and motor starters’ control functions. The best companies offer free consultations and provide customized and highly reliable panel products.
