How does a dynamic brake primarily function?

A dynamic brake primarily functions by generating resistance in the electric motor. In electric trains, dynamic braking involves switching the traction motors to operate as generators when the train needs to slow down. When the train's speed is reduced, the rotational energy of the train’s wheels is converted back into electrical energy through the motor. This process creates resistance, which helps to slow the train down without relying on traditional friction brakes.

Dynamic braking is efficient because it allows the train to convert kinetic energy into electrical energy, which can be dissipated as heat or sometimes fed back into the power supply system. This method reduces wear on mechanical braking systems and is particularly useful for maintaining control on descents or during emergency stops. The effectiveness of dynamic braking is a key aspect of modern train operation, leveraging the train's own electrical system to assist in slowing down.