A motor starter is a device that manually or automatically switches to start and stop an electric motor to provide overload protection for the motor circuit. Key specifications include electrical specifications such as intended use, starter type, number of phases, current, voltage, power rating, and other features. Motor starters are used when an electric motor operates at a particular horsepower. There are various types of starters, including manual, magnetic, soft starter, multi-speed, and full voltage types. Explore the various types of Motor starter switches and why you should get one.
The working of a motor starter:
A motor starter switch consists of two devices: a contactor that closes the circuit to the motor and an overload relay that monitors the current drawn by the motor. This overload protection device is set to the specified maximum load that the motor can safely handle. When the engine exceeds its maximum load, the device opens the engine starter control circuit and stops the engine.
The main functions of the motor starter are as follows.
- To start the engine safely
- How to stop the motor safely
- Reverse the direction of rotation of the motor
- To protect the motor from low voltage and overcurrent.
The need for a motor starter:
One needs a motor starter to start an induction motor because of its rotor impedance. The high inrush current magnetizes the air gap between the rotor and the stator, inducing EMF in the rotor windings. This EMF creates an electric current in the rotor winding, which creates a magnetic field to generate torque in the rotor. As the rotor speed increases, the motor slips less, and the current drawn by the motor decreases.
When the current exceeds 5-8 times the actual current, the overload of current can cause damage to the motor as well as to the main supply line. And in a result, it can harm the appliances connected to the main supply line.
To protect the motor from such high currents, a starter is used that limits the initial current at startup for a short period of time, and when the motor reaches a certain speed, a normal power supply to the motor is resumed. It also provides protection against fault conditions such as Undervoltage and overcurrent during normal operation.
While there are different types and techniques of motor starters, a single-phase motor starter switch by Wipro NW is the idle one to protect your house from electrical hazards due to the overload of current.