Final answer:
Start windings are in the circuit until the rotor reaches 75-80% of rated speed, after which a centrifugal switch opens, allowing the motor to run on the main winding. Motor and wind turbine efficiency is closely managed to prevent damage and overheating.
Step-by-step explanation:
The start winding of a motor is part of the circuit that helps to begin the rotation of the motor's rotor. It is only in the circuit until the rotor reaches about 75-80% of its rated speed. At this point, a normally closed centrifugal switch opens, removing the start winding from the circuit. Subsequently, the motor will continue to operate using only the main or run winding. This is crucial because if the start winding were to stay engaged, it could overheat due to the larger current it would draw at the normal operating speed.
In applications like wind turbines, maintaining optimal speeds is critical to prevent damage. Turbines are designed to maximize efficiency at specific wind speeds and can adjust blade angles to reduce efficiency when wind speeds get too high. Similarly, electric motors must avoid overheating by operating within their design limits, ensuring they are not subjected to larger currents than necessary, which can occur if the motor runs at too low a speed.