Regeneration system is mounted on all electric locomotives designed for driving freight trains. There has been a tendency of its use in combination with dynamic brake on passenger locomotives and electric trains.

The objective of the authors is to analyze regulatory and protection functions of electrical equipment and its operation in regenerative mode, using analytical method, mathematical calculations, simulation and comparative method.

Regenerative braking should be considered as the most effective means of reducing energy consumption in electric traction. Therefore, its scope should be expanded, including its use for returning of kinetic energy of the train to electric traction network. The authors present a methodology for calculating the energy when an electric locomotive moves downhill, analyze individual components of the energy balance, indicate possibility of increasing the efficiency of the locomotive in regenerative behavior. An analytical review of regulatory and protection functions of electrical equipment was carried out and has shown that in regenerative behavior a set of these functions is much broader than in traction. Electric equipment, implementing regeneration, should be improved using new technologies (static converters, onboard microprocessors, high-speed protection). It is necessary to keep the achieved level of functional reliability and maintain proven schematics, including crosscyclic excitation of traction electric motors.