Why must a train NOT be operated for long periods with its master controller held in the switching position?

The reason a train must not be operated for extended periods with its master controller held in the switching position primarily concerns the potential damage to the accelerating resistance. In this context, the term "switching position" refers to a setting that could keep the train in a state where energy is continuously applied without the necessary ceasing or reducing of power.

When the master controller is held in this position for too long, it can generate excessive heat in the accelerating resistance components due to continuous current flow. This can lead to overheating and eventual burnout, compromising the function of the electrical system and potentially leading to costly repairs or operational failures.

Maintaining the train in the switching position for long durations not only poses risks to the hardware but also impacts the overall safety and performance of the train, making it crucial to operate the master controller correctly to prevent any damage to the system.