How to Avoid Various Load Problems of Power Capacitors

I. Overload Problems and Countermeasures

Capacitor overload is usually caused by excessive system voltage or high harmonic current. Long-term overload will accelerate the aging of internal insulation medium and even cause thermal breakdown in severe cases. To avoid this problem, it is recommended to reserve sufficient safety margin during model selection and install overvoltage protection devices. Meanwhile, regularly detect the harmonic content in the power grid. If harmonics exceed the standard, consider installing filter reactors to effectively suppress harmonic current and ensure the capacitor operates within the rated load range.

II. Impact Caused by Frequent Switching and Protection

In occasions with frequent load changes, repeated switching of capacitors will generate huge inrush current and overvoltage, causing cumulative damage to equipment insulation and switch contacts. To alleviate this situation, special switching switches with pre-charging function shall be adopted, and the delay setting of the automatic compensation controller shall be optimized. In addition, the graded switching mode can be considered, dividing the capacitor bank into multiple small groups and gradually putting them into operation according to the actual reactive power demand, so as to greatly reduce the single impact intensity.

III. Abnormal Load Caused by Environmental Factors

Excessively high ambient temperature or poor ventilation will lead to difficult heat dissipation of capacitors, exposing them to overheating risk even under normal load. Sufficient heat dissipation space shall be reserved around the equipment during installation, and dense arrangement of multiple capacitor groups shall be avoided. For indoor installation occasions, it is recommended to install ventilation or air conditioning equipment to control the ambient temperature within the range specified by the manufacturer.

IV. Occurrence and Avoidance of Resonance

When the parameters of capacitors and system inductance are improperly matched, series or parallel resonance may occur, causing local abnormal voltage rise and current distortion. Detailed harmonic analysis and resonance point calculation shall be carried out in the design stage to prevent the capacitor parameters from coinciding with the natural frequency of the system.