What happens when the contacts of an SF6 gas breaker are opened?

When the contacts of an SF6 gas breaker are opened, the operation of the breaker results in an arc that forms between the separating contacts. SF6 (sulfur hexafluoride) is an excellent insulating gas with superior properties that allow it to effectively extinguish arcs.

When the contacts open, the electrical current flowing through the circuit attempts to continue, which creates an arc due to the ionization of the gas between the opened contacts. However, the SF6 gas quickly cools and ionizes, which helps to quench or extinguish the arc. In essence, the SF6 gas blast serves both to insulate the open contacts and to cool down and de-ionize the area, effectively stopping the flow of electricity.

This arc-extinguishing mechanism is crucial for the reliable operation of high-voltage systems, as it prevents damage to the breaker components and helps maintain safe operating conditions in electrical networks. The other options do not accurately reflect the function and behavior of an SF6 gas breaker when it operates, as they either refer to unrelated phenomena or incorrectly describe the functioning of the breaker during the opening of contacts.