Dynamic Retarding Inverter (DRI) (4): The Dynamic Retarding Inverter controls the Grid Blower Motor. The DRI receives DC power from the Dynamic Retarding Grid. This DC power is inverted to AC; the threephase AC output is used to control the speed of the Retarding Grid Blower.
DRI Capacitor (5): This protects the Dynamic Retarding Inverter from transient voltages during Contactor operation.
Crowbar Assembly (6): The Crowbar is an electronic device that sends power on the DC Bus to the second circuit of the Dynamic Retarding Grid during fault and shutdown conditions. Other components located on this assembly are the DC Bus Voltage Sensor, Ground Fault Sensor and shunt resistor, and the Ground Relay Capacitor.