1. Inconvenient Installation
Because oil-filled cables cannot be removed from pressure tanks and other facilities at any time, installation becomes significantly more difficult and complex, requiring a high level of expertise from construction personnel. For example, if the cable needs to be cut during installation, carelessness can lead to loss of insulating oil or the entry of moisture and steel shavings into the insulation, creating hidden dangers.
2. High Flammability
The insulating oil used in oil-filled cables is a flammable liquid with a low flash point (typically below 140°C for low-viscosity oils), making it highly flammable. The end-capping process requires the use of open flames such as blowtorches, which can easily ignite a fire. Furthermore, if an oil-filled cable line catches fire due to external factors or cable head explosions, the cable's "flammability" can cause serious fires. Such incidents have occurred numerous times both domestically and internationally. A typical example is the Grand Coulee Hydropower Plant in the United States, where a fire in oil-filled wiring in a generator unit caused the shutdown of six cable circuits and a 2700 MW generator.
3. Restricted drop heights
The metal sheath of oil-filled cables must withstand the effects of internal oil pressure. When installed at high drop heights, the static oil pressure increases. While technical measures such as increasing sheath thickness, strengthening armor, or using plug-type connectors can address this, technical and economic factors still significantly limit the installation height.
4. Implement anti-vibration measures when used in vibrating locations
The metal sheath of oil-filled cables can develop fatigue cracks after prolonged exposure to vibration. Therefore, special anti-vibration measures are necessary for oil-filled cables installed on bridges or other locations subject to vibration.
