Fault Phenomenon: Komatsu 830E electric wheel mining truck during long downhill grades, the resistor grid cabinet reports an overtemperature alarm, braking force decreases.

Troubleshooting Process:
– Checked fans: cooling fan motor failed or air duct clogged.
– Checked resistor strips: resistor strips deformed or shorted.
– Checked sensors: temperature sensor false alarm.
– Checked control: excessive braking current setting.

Root Cause: The cooling air duct of the resistor grid cabinet is clogged with coal dust and debris, preventing heat from dissipating.

Required Parts: Clean resistor grid cabinet air duct, inspect fan motor.