What are the Advantages and Disadvantages of Regenerative Braking?

What is Regenerative Braking?

The method of braking in which no energy is drawn from the supply system during braking period and some of the energy (kinetic energy of rotating parts) is fed back to the supply system is known as regenerative braking.

The regenerative braking is the most efficient method of electric braking to the driving motor of locomotives. The regenerative braking can be applied to both AC and DC motors.

Advantages of Regenerative Braking

The advantages of the regenerative braking include the following −

  • In case of regenerative braking, a part of electrical energy is returned to the supply system, so the total energy consumption for the run in electric traction is considerably reduced (about 20 to 30%). Consequently, a considerable saving in the operating cost.

  • By employing regenerative braking, the wear of the brake shoes and wheel tyres is reduced to considerable extent. Therefore, their life is increased and replacement cost is decreased.

  • By using the regenerative braking in the electric traction, higher value of braking retardation is obtained so that the vehicle can be brought to rest quickly and the running time is considerably reduced.

  • As braking power is obtained by the regenerative braking, only a small amount of brake dust is produced when mechanical brakes are applied.

  • As the regenerative braking provides high braking retardation, so high speeds of the train are possible while going down the gradients or slopes.

  • If regenerative braking is provided, then propulsion of heavier trains on gradients is possible without dividing them into sections with speed and safety.

Disadvantages of Regenerative Braking

The disadvantages of regenerative braking in electric traction are as follows −

  • When regenerative braking is used in electric traction, then additional equipment is required for control of regeneration and for protection of equipment and machines. It increases the initial and maintenance costs of the traction system.

  • In case of regenerative braking, owing to recuperated energy the operation of the substations becomes complicated and difficult.

  • In case of regenerative braking, the size of the DC machines used is larger than those ordinarily employed. Thus, the weight of the locomotive and hence the required mechanical strength and cost increase.

  • In case of regenerative braking, when substations employing mercury arc rectifiers for conversion purpose, it requires additional equipment either to deal with regenerated energy separately or to change one or more of the ordinary rectifiers over to inverted operation. No such difficulty is experienced in case of substations that use rotary converters or motor-generator sets for conversion purpose.

  • When regenerative braking is used in traction system, then it is necessary to provide multistage braking schemes, i.e., the regenerative braking is employed only down to a speed of 16 kmph, then rheostatic braking is used to about 6.5 kmph and then the mechanical braking is required to bring the locomotive to rest. Thus, only by employing the regenerative braking, the locomotive cannot be stopped.

Updated on: 20-May-2022

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