What happens to the magnetic field in a synchronous motor when the load increases?

In a synchronous motor, when the load increases, the magnetic field remains constant while the motor struggles to maintain its synchronous speed. This is a key characteristic of synchronous motors. They have a fixed magnetic field established by the rotor, which rotates at a speed determined by the supply frequency.

As the load increases, the motor experiences more mechanical resistance, which can lead to a reduction in speed if the load exceeds the motor's capacity to maintain synchronous operation. However, the magnetic field created by the rotor does not change or strengthen in response to load variations; it is designed to remain consistent as long as the machine operates within its rated capacity.

The other possible outcomes related to the magnetic field either imply a significant operational failure or an immediate shutdown, which typically do not happen under normal load variations. Thus, the correct understanding of the operation of synchronous motors is captured through the recognition that the magnetic field remains steady while the speed may fluctuate under load changes.