Which starting method is considered relatively more expensive for motors?

The choice of line impedance starters as the method that is relatively more expensive for motor starting can be understood by evaluating the components and operational requirements of this method. Line impedance starters utilize resistors or inductors in the starting circuit to limit the starting current of the motor. While they effectively reduce the inrush current and provide a smoother ramp-up of motor speed, they involve additional equipment and costs associated with the resistive or inductive components. This extra complexity and hardware can lead to higher installation and maintenance expenses compared to simpler starting methods.

In contrast, other methods may either use less expensive components or have a less complicated setup. Direct-on-line starting is straightforward and typically involves a motor connected directly to the power supply, requiring fewer components and thus lower costs. Similarly, star-delta starting reduces the initial current through a clever switching method but involves basic relay components that are generally less expensive than the components used in line impedance starters.

Auto-transformer starting also adds costs due to the transformer component; however, line impedance starters are often seen as having the highest overall expenses due to their complexity and the need for specialized equipment. Thus, line impedance starters are viewed as the more expensive starting method for motors.