Tower cranes operate outdoors for long periods, subject to various environmental factors such as sun exposure, rain, dust, oil contamination, mechanical friction, and temperature differences between day and night, which can lead to sealing failure, insulation layer aging and damage, and grounding protection malfunction in the electrical control boxes, power cables, and motor circuits. These issues can result in minor equipment shutdown faults or even serious incidents such as electric shock and lifting safety accidents. To address this, the project has clearly defined standardized daily maintenance procedures, divided the electrical protection, insulation testing, grounding and lightning protection, and hazard rectification into four management modules, and established a three-level inspection mechanism of pre-shift, weekly inspection, and monthly inspection.
In terms of the daily maintenance of the electrical system protection, the operators conduct a comprehensive inspection of the electrical control cabinets, linkage operation consoles, resistance boxes, and frequency converter boxes every day. They promptly replace the aged and cracked sealing rubber strips, clean the blocked heat dissipation filters, and replenish the missing cover plates and protective components of the boxes. For the cables running along the rotating arm, slewing, luffing, and trolley traction areas with high wear and tear, they focus on checking for scratches, cracks, rat bites, and compression deformation on the outer skin. They improve the rubber buffer guards and corrugated pipe protections, and reserve a reasonable slack for the cables. They also prevent direct abrasion of the insulation layer by the sharp edges of the steel structure. At the same time, they ensure proper control of rain, moisture, and lightning protection. They clear the drainage holes on the equipment top, regularly inspect the grounding flat steel and lightning arrester connection conditions, remove rust and repaint the corroded areas, and add steel pipes for protection against rolling pressure for underground laid cables.
For various common potential hazards related to insulation deterioration, on-site implementation of closed-loop corrective measures is carried out: For minor cable insulation damage, multi-layer wrapping with high-voltage insulating tape is adopted; for the damaged sections of the copper core that are exposed and damaged, they are directly cut off and re-pressed for protection; when equipment gets damp and condenses, the dehumidification heater and ventilation drying elements inside the cabinet are turned on; regular cleaning of cement dust and oil stains on the terminal surfaces is carried out to prevent corrosion of the insulation layer; all connection terminals are tightened every shift to prevent false connections and overheating that may cause the cables to burn out. At the same time, grounding protection maintenance is carried out in a coordinated manner, and the grounding resistance of the entire machine is re-measured monthly to ensure the resistance is ≤ 4Ω; it is strictly prohibited to connect grounding wires in series and to replace the grounding wire with steel wire ropes; the leakage protection device's tripping function is tested daily to protect the device; if the protection device fails, it should be replaced immediately.
The project also clearly defines the red line for electrical maintenance, prohibiting the removal of protective sleeves, box covers, arc extinguishing covers, etc.; direct binding of steel wires or iron wires to cables is prohibited; equipment with unqualified insulation or failed leakage protection is strictly prohibited from being put into construction; and prohibited operations such as unseparated mixed laying of power and weak lines. All inspection and insulation test data are uniformly registered in the special equipment maintenance ledger, detailing the detection time, environmental conditions, insulation values, hazard points, and corrective measures, ensuring full traceability throughout the process.
