Meggitt is developing energy dissipators for traction-drive systems.

Energy dissipation is a key element in traction drive systems because the motors are used to decelerate and stop a vehicle. Under certain conditions such as steep grades or heavy braking, the energy cannot be absorbed by the batteries and must be disposed of elsewher in the system.

Energy dissipators dispose of this excess energy using banks of resistors arranged inside a duct or vessel. When necessary, the drive connects the power bus to the dissipator wher excess energy is dissipated as heat.

A cooling medium such as air or oil is supplied to the dissipator to take away the heat. In many cases, energy must be stored in the dissipator for a short time because the dissipation rate exceeds the heat transfer capability.

Meggitt dissipators use special resistor materials and advanced heat transfer methods to produce equipment that is small and light.

The energy dissipater is used to dissipate the energy generated by the traction motor when the vehicle is going downhill.  It is comprised of a bank of bulk ceramic resistors arranged in a staggered array.  The assembly can either be air cooled or liquid cooled.