MININGRESISTOR BREAKING GRID

The Dynamic Brake Grid Box will be used as the electric retarder (brake) on an off highway Haul Truck. It will dissipate the electricity that will be generated by the rear wheel motors for the speed control of the Haul Truck. The Grid resistors will be cooled by a fan driven by a dedicated AC controller. The blower will be used for cooling of the grids only the blower motor will be controlled by the drive system using power from a DC bus. The Dynamic brake grid box will be separated into 4 sections. Each section is controlled by a chopper. The chopper control module will only switch one section at a time. The chopper control reacts to bus voltage and responds by switching on grid banks to lower the bus voltage to a preset value.