The Airpax/Sensata 209 series hydraulic magnetic circuit protectors are designed for branch circuit applications such as EDP, air conditioners, panel boards, and lighting controls. These circuit breakers combine power switching with accurate and reliable circuit protection in a compact, single or multi-pole unit. Utilizing the hydraulic-magnetic principle, the 209 family adapts to local applications and environments, minimizing nuisance tripping due to temperature variations. The optional inertial delay effectively handles inrush currents from ferroresonant transformers, lamps, and capacitive filters. The 209 series withstands high pulses without tripping or affecting normal delay curves.