What is the primary function of puffer tubes in medium voltage air circuit breakers?

The primary function of puffer tubes in medium voltage air circuit breakers is to blow air through a tube and nozzle to each contact assembly. This process is crucial for the operation of the circuit breaker, particularly during the interruption of the current. When the circuit breaker operates and the contacts begin to separate, the puffer tube compresses air and forces it through the nozzle directed at the arc formed between the separating contacts. This airflow cools and helps extinguish the arc, ensuring that the circuit can be interrupted safely and effectively. The use of puffer tubes contributes to the reliability and performance of the circuit breaker, making them an essential component in medium voltage applications.