Following the state of the art, rail-bound vehicles are equipped with three-phase current motors whose acceleration, speed and braking are controlled by means of power electronics. During braking, the kinetic energy of the vehicle is transformed into electrical energy, returned to the grid wherever possible, and thus reused. However, this requires a grid that can take on such energy at any time. Otherwise, the grid voltage would simply rise and the brakes will not work. Another method is to convert the braking energy into heat using a braking resistor.

Braking resistors are used as

• additional brake for energy return to the grid,
• to take off some stress from the mechanical brake
• and as an emergency brake resistor.

Electrical braking is wear-free and can be optimally controlled so that no abrupt changes in braking occur which the passengers may resent.

Cooling

In view of the large amounts of heat to be dissipated, braking resistors require sufficient cooling air. Depending on the cooling type

• natural air cooling and
• forced air cooling

 
braking resistors are available.

Natural air cooling

resistors are mainly installed on the outside of the vehicle aned in some cases the airstream can effectively support cooling.