This phenomenon is known as the "skin effect" and is due to the way that alternating current (AC) behaves. As the frequency of the AC increases, the current tends to flow on the outer surface of the conductor, rather than evenly throughout the entire cross-section. This means that the conductor can be made smaller without affecting its performance, resulting in a smaller overall size for the transformer or motor.
The skin effect causes an increase in resistive losses, which can lead to decreased efficiency and potentially damage the equipment. This is why it is important to consider the frequency of operation when designing transformers and motors.
Yes, the size of a transformer or motor is also influenced by the amount of power it needs to handle and the desired level of efficiency. Higher power and efficiency requirements may result in a larger size, even at higher frequencies.
No, there are practical limits to how high the frequency can be increased before other factors, such as eddy currents and dielectric losses, become significant and limit the size reduction. Additionally, the size reduction may not be justified if the cost of higher frequency components outweighs the benefits of a smaller size.
In addition to the limitations mentioned above, using higher frequencies may also lead to increased electromagnetic interference (EMI) and higher costs for specialized components and materials that can handle the higher frequencies. It is important to carefully consider the trade-offs and determine the optimal frequency for a given application.