Fault Phenomenon: Zoomlion ZCC large crawler crane hoist mechanism inverter displays overcurrent alarm, mechanism cannot move.

Troubleshooting Process:
– Checked motor insulation: normal.
– Checked cable connections: terminals loose and hot.
– Checked braking resistor: resistor open circuit.
– Tightened connections and replaced braking resistor.

Root Cause: The braking resistor was open circuit, preventing regenerative energy from being dissipated, causing the inverter DC bus voltage to rise excessively and triggering overcurrent protection.

Required Parts: Braking resistor set.