What is the typical factor of momentary high inrush currents during motor starting compared to normal running current?

The typical factor of momentary high inrush currents during motor starting, which can be around 20 times the normal running current, is significant in understanding motor behavior. When an electric motor starts, it requires an initial surge of current to overcome inertia and begin turning. This inrush current is much higher than the current required when the motor is operating at a steady state, as it must provide enough torque to start the load.

The reasoning behind the factor of 20 is rooted in the motor's physical properties and electrical characteristics. The inrush current is influenced by the motor type, design, and load characteristics. Understanding this high inrush is crucial for circuit design, protection sizing, and ensuring that the electrical infrastructure can handle these peaks without tripping or causing damage.

Additionally, knowing that the inrush current can reach up to 20 times the normal running current helps engineers and technicians to appropriately size breakers and fuses and design systems that accommodate this temporary increase without failing.