Fault Phenomenon: Komatsu 930E electric wheel mining truck during braking or driving, the main rectifier cabinet reports a fault, vehicle loses power.

Troubleshooting Process:
– Checked diodes: multimeter measurement shows multiple diodes shorted or open.
– Checked cooling: cooling fan failure causing overheating.
– Checked voltage: excessive grid voltage fluctuation.
– Checked fuses: fast-acting fuses blown.

Root Cause: High-power diodes in the main rectifier cabinet shorted due to poor cooling or voltage spikes, causing a bridge arm short circuit.

Required Parts: Replace damaged diodes and fuses, clean cooling air duct.