What happens to the current requirement of an induction motor when started directly connected to the source?

When an induction motor is started directly connected to the power source, it experiences a high inrush current, often referred to as starting current, which can be as high as six times its rated full-load current. This phenomenon occurs because the motor is initially at rest and requires a significant amount of current to overcome inertia and build up the magnetic field necessary for operation.

As the motor starts, the rotor is stationary, and there is maximum slip between the stator's magnetic field and the rotor, leading to a significant voltage drop across the motor's windings. This results in a large current draw to establish the torque needed for the motor to begin turning. Once the motor accelerates and reaches near its synchronous speed, the current rapidly decreases to the normal full-load current level.

Understanding this starting current behavior is critical for selecting the appropriate power supply, circuit protection devices, and control methods to ensure the motor operates safely and efficiently without damaging the electrical systems it's connected to.