The Airpax/Sensata 209 series combines power switching with accurate and reliable circuit protection in a compact single or multi-pole unit. This family of circuit breakers is designed for branch circuit applications such as EDP, air conditioners, panel boards, and lighting controls. Utilizing the hydraulic-magnetic principle, these protectors adapt to local applications and environments, minimizing nuisance tripping due to temperature variations. They withstand high pulses without affecting normal delay curves, providing robust protection for a wide range of industrial applications.