Under what circumstances can the low-voltage compensation capacitor be operated?

Low-voltage compensation capacitors are crucial equipment in power systems used to enhance power factor and reduce line losses. Their operation must meet specific conditions; otherwise, it may lead to safety hazards or affect the compensation effect. In the following, we will elaborate on the operating requirements of low-voltage compensation capacitors.

Ⅰ. Voltage conditions

Low-voltage compensation capacitors must operate within the rated voltage range. Generally, their operating voltage should not exceed 1.1 times the rated voltage; otherwise, it may cause insulation aging or even breakdown. At the same time, low voltage will affect the compensation effect and result in a less significant improvement in power factor. Therefore, stable grid voltage is one of the basic conditions for the normal operation of low-voltage compensation capacitors.

II. Environmental Temperature Requirements

The environmental temperature has a significant impact on the lifespan and performance of low-voltage compensation capacitors. Generally, the operating environment temperature should be controlled within the range of -25℃ to +45℃. Excessive temperature will accelerate the aging of the internal medium of the capacitor, shortening its service life; while low temperature may affect the startup performance of the capacitor. In extreme climatic conditions, additional cooling or insulation measures need to be taken.

III. Harmonic Content Limitation

When the harmonic content in the power grid is too high, the low-voltage compensation capacitors may be overloaded or even damaged due to the amplification of harmonics. Therefore, in cases with severe harmonics, reactors or filtering-type compensation devices should be installed. Before operation, harmonic tests should be conducted to ensure that the harmonic distortion rate complies with national standards (usually THD <= 5%), otherwise corresponding treatment measures should be taken.

IV. Load Matching Capability

The capacity of the low-voltage compensation capacitor should be reasonably configured according to the load changes. If the compensation capacity is too large, it may lead to over-compensation, causing the grid voltage to rise; if the capacity is too small, it will not be able to achieve the desired effect of improving the power factor. It is recommended to use an automatic switching device to dynamically adjust the compensation capacity based on the real-time load, ensuring the stable and efficient operation of the system.