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. Utilizing the hydraulic-magnetic principle, these protectors adapt to local environments and minimize nuisance tripping due to temperature variations. They withstand high pulses without affecting normal delay curves and are available in one to six pole assemblies with various configurations and terminal styles. The 249 Power Selector Breaker System combines magnetic-hydraulic branch circuit overload protection and a power system selector switch in one device, allowing selection of multiple power systems.