What role do grading capacitors play on an EHV breaker?

Grading capacitors play an essential role in the operation of an Extra High Voltage (EHV) breaker by protecting the main contacts from arc re-strike. When an EHV breaker operates, it opens and closes under high voltage conditions, which can lead to the generation of arcs between the contacts. If an arc re-strikes, it can interfere with the breaker's ability to effectively interrupt current and may damage the components over time.

Grading capacitors are used to distribute the voltage more evenly across the breaker's contacts. This helps in minimizing voltage gradients and thereby reduces the potential for arcing. By effectively dampening rapid changes in voltage and maintaining a stable electrical environment around the contacts during operations, grading capacitors ensure that the main contacts can open and close rapidly and safely without the risk of an arc re-strike, thus enhancing the reliability and longevity of the breaker.

This functionality is vital, as managing high-voltage conditions is crucial in maintaining the performance and safety of electrical systems within substations. Other options, such as increasing current flow, adjusting voltage level, or absorbing shock, do not accurately describe the primary purpose of grading capacitors in EHV breakers.