The advantages of using insulating oil as the filling material for low-voltage power capacitors

Low-voltage power capacitors are key equipment for reactive power compensation, improving power factor, enhancing power quality, and reducing line losses. The protection of internal components and the stability of their operational performance are of utmost importance, and the selection of the filling medium plays a central role in this. Although dry capacitor technology is constantly evolving, using high-performance insulating oil as the filling material remains the preferred option in many application scenarios, as its multiple benefits are irreplaceable.

Ⅰ. Outstanding heat dissipation performance ensures stable operation.

When a capacitor is in operation, the capacitor core inside it will generate heat due to the action of the alternating electric field. If the heat accumulates, it will accelerate the aging of the dielectric material, cause the capacity to decrease, and even lead to thermal breakdown.

1. High thermal conductivity: Insulating oil has a much higher thermal conductivity than air. It can quickly absorb the heat generated by the capacitor core and conduct it to the capacitor housing, which then dissipates the heat into the surrounding environment.

2. Uniform temperature effect: The flow characteristics of the insulating oil ensure a more uniform temperature distribution throughout the entire capacitor, preventing the formation of localized hotspots, thereby significantly enhancing the reliability and lifespan of the equipment during long-term operation.

Ⅱ. Excellent insulation performance, enhancing electrical strength

The internal space of the capacitor is limited. Extremely high insulation levels are required between the electrodes, as well as between the components and the casing, to withstand the working voltage and possible overvoltage surges.

1. Enhance dielectric strength: High-quality insulating oil (such as benzyl toluene, epoxy propylene, etc., which are environmentally friendly oils) has extremely high dielectric strength. It can effectively fill all voids, prevent air ionization, significantly enhance the overall insulation tolerance, and reduce the risk of internal partial discharge.

2. Repairing insulation defects: Insulating oil can penetrate into the tiny flaws within the dielectric film of capacitor components, to some extent "repairing" these insulation weaknesses, thereby enhancing the overall electrical strength of the capacitor core.

III. Effectively suppress local discharge and extend the core's lifespan

Partial discharge is one of the main causes leading to the aging and eventual failure of capacitor insulating materials. It is caused by the ionization of air at the concentrated areas of the electric field.

1. Elimination of air: The insulating oil completely submerged and filled all the voids within the capacitor core, eliminating the air that is prone to ionization, thereby fundamentally eliminating the conditions that lead to local discharge.

2. Protecting the metallized film: For the widely used metallized film capacitors, local discharge can erode the evaporated metal layer, resulting in capacity loss. The effective impregnation with insulating oil can perfectly suppress the discharge, protect the electrodes, and ensure stable capacity.