US Patent 9576757 Circuit interrupters with air trap regions in fluid reservoirs

Circuit interrupting devices, power distribution switchgear assemblies, and pole units for power distribution are provided. A circuit interrupting device includes a solid insulation housing, a disconnect, a window, and an insulating fluid. The solid insulation housing defines a first external opening and a first cavity extending into the solid insulation housing from the first external opening. The disconnect has a moving contact in selective engagement with a stationary contact in the first cavity. The window is secured to the solid insulation housing at the first external opening. The insulating fluid is disposed within the first cavity. The window, the solid insulation housing, or a combination thereof is configured to form a trap region that is in fluid communication with the first cavity and is configured to trap air bubbles in the insulating fluid.