Grid-connected wind power technology emerged in the 1980s and rapidly achieved commercialization and industrialization, gaining increasing attention as a new energy technology in many countries. After more than a decade of development, domestic wind farms have grown from initial installed capacities of several hundred kilowatts to large-scale wind farms with installed capacities of tens of thousands or even hundreds of thousands of kilowatts. The single-unit capacity of wind turbines has increased from tens of kilowatts initially to several hundred kilowatts today, and megawatt-class wind turbines are gradually appearing in domestic wind farms. In recent years, with the continuous increase in the single-unit capacity of wind turbines and the gradual accumulation of their operational time, turbine downtime caused by gearbox failures or damage has become increasingly frequent, resulting in greater direct and indirect losses and a rising workload for maintenance personnel. This has prompted more and more wind farms to strengthen daily monitoring and regular maintenance of gearboxes. For example, at our farm, from 2000 to 2002, the average annual direct power loss due to gearbox failures or damage was approximately 150,000 kWh, accounting for more than 40% of the non-routine maintenance workload. Because grid-connected wind turbines start and stop frequently, and the rotors themselves have a large moment of inertia, the rotor speed of medium and large wind turbines is generally designed to be 20-40 rpm. The larger the turbine capacity and the longer the rotor diameter, the lower the speed. To meet the working conditions of asynchronous dual-speed motors, a gearbox is needed between the rotor and the generator to increase speed. Due to the size limitations of the nacelle, the mechanical transmission system of large wind turbines is generally arranged along the nacelle axis, and the gearbox has changed from the previous multi-stage spur or helical gearboxes to more compact planetary gearboxes. As the torque transmitted by the gearboxes used in large wind turbines increases, the structure becomes more compact and complex, and the requirements for wind turbine maintenance personnel are constantly increasing. [b]1. Daily Maintenance and Periodic Maintenance[/b] [b]1.1 Daily Maintenance[/b] The daily maintenance of wind turbine gearboxes mainly includes: equipment appearance inspection, lubrication oil level inspection, electrical wiring inspection, etc. Specific tasks include: When operating the unit, personnel should clean the gearbox housing surface, check for leaks in the housing and lubrication lines, and ensure the external lubrication lines are secure. Due to the significant vibration of the wind turbine, poorly secured external lines can damage pipe joint seals or even cause line breakage. Additionally, check for looseness and leaks in the drain valve at the bottom of the gearbox to prevent excessive gear oil leakage. Check the oil level and color using the dipstick or oil level window; replenish oil promptly if the level is low. If the oil color becomes noticeably darker (black), consider oil quality testing and strengthen monitoring of the unit's operation. Promptly inspect and address any filter blockage alarms. When replacing the filter element, thoroughly clean the inside of the filter; ideally, disassemble the entire filter assembly for cleaning and inspection in the workshop. When installing the filter housing, ensure the threads are aligned correctly and apply force evenly to avoid damaging the threads and seals. Check the wiring of sensors for gear oil level, temperature, pressure, differential pressure, bearing temperature, etc., as well as heaters and radiators, to ensure they are normal and that the wires are not worn. During routine inspections, pay attention to any abnormal noise levels in the unit and promptly identify potential faults. [b]1.2 Regular Maintenance[/b] Regular maintenance of wind turbine units mainly includes: checking the torque of gearbox connecting bolts, checking gear meshing and tooth surface wear, testing sensor functions, checking the lubrication and cooling system functions, regularly replacing gear oil filters, and collecting oil samples. When possible, use relevant industrial testing equipment to analyze vibration and noise levels in the gearbox to gain a more comprehensive understanding of its operating status. According to the wind turbine operation and maintenance manual, different manufacturers have different sampling cycles for gear oil. Generally, sampling is required once a year, or once every two years. For gearboxes exhibiting abnormal operating conditions, oil samples should be collected as needed. The service life of gear oil is generally three to four years. Because gearboxes vary in operating temperature, annual operating hours, and peak output, simply using time as a general guideline for gear oil changes may not guarantee economical and safe operation under different operating conditions. This necessitates that operators regularly collect and organize various operating data from the unit, compare and analyze the parameters of oil testing results, and determine an oil change cycle that better suits the operating characteristics of their specific electric field.