I. Operating Standards for Compensation Capacitors

Voltage
Operating compensation capacitors at normal voltage levels is critical for their reactive power compensation performance. Capacitor banks can operate continuously at up to 1.1 times their rated voltage. However, overvoltages may occur during operations such as switching, voltage adjustments, and load variations. Capacitor banks can tolerate short-term overvoltages depending on their magnitude.

Current
Capacitor banks can operate continuously at up to 1.3 times their rated current. Of this 30% increase:

10% results from permissible power frequency overvoltages.

20% is caused by higher-order harmonic voltages.

Causes of overcurrent during operation include:

1.Positive deviations in capacitance value.

2.Bus voltage exceeding the capacitor's rated voltage.

3.Harmonic voltages present in the power grid.

4.High voltages due to light-load operation of the grid.

5.Grid frequency higher than the rated frequency.

6.Transient overvoltages caused by faults or operations.

Temperature
Capacitors lack copper or iron losses; their heating is determined by dielectric losses, which are directly influenced by capacitance, frequency, voltage, and the insulation properties of the dielectric medium.
Excessive temperature shortens capacitor lifespan and may lead to dielectric breakdown, causing capacitor damage. Temperature requirements typically range from -40℃ to 40℃ for general capacitors and -45℃ to 50℃ for self-healing capacitors.

II. Precautions During Compensation Capacitor Operation

1.Ensure the ambient temperature does not exceed 40℃, with a 24-hour average temperature below 30℃. If exceeded, apply artificial cooling or remove the capacitor from operation.

2.Avoid simultaneous occurrences of maximum voltage and maximum temperature to extend the capacitor's service life.

3.Capacitors may operate at up to 1.3 times their rated current, but long-term overvoltages and harmonics in the circuit should be mitigated.

4.Regularly clean dust and dirt from surfaces of bushings, capacitor shells, related equipment, and frames. A comprehensive cleaning should be done at least quarterly.

5.Limit the frequency of power frequency overvoltages. During the capacitor's lifetime, occurrences exceeding 1.15 times the rated voltage should typically be limited to 200 events.

6.When energizing unloaded transformers or parallel reactors under light loads, avoid ferroresonance and resulting overcurrents by disconnecting the capacitors before energizing.

7.Inspect all contact points in the capacitor circuit regularly to ensure they are secure, as loose connections may lead to capacitor or system failures.

8.Check the fuse protecting the capacitors at least monthly to monitor the capacitor's status and ensure normal operation.

9.If capacitor casing leakage is detected, repair minor leaks using tin-lead solder, and replace units with severe oil leaks.

10.Conduct frequent inspections of the capacitor room and maintain detailed operational records to identify and address issues promptly.