Sensor-tripper apparatus for a circuit interrupter

A sensor-tripper apparatus for tripping a primary circuit interrupter comprising

• a frame,
• a conductive tube mounted on said frame,
• a trip rod mounted for axial movement in said tube,
• a thermal sensing strip having a predetermined Curie temperature and being mounted on said frame and having means for connecting in series with a primary circuit,
• a magnet assembly mounted for axial movement on said tube into engagement with said sensing strip and being operatively connected to move said trip rod,
• spring means mounted between said magnet assembly and said sensing strip for biasing said magnet assembly away from said sensing strip when said strip reaches its Curie temperature,
• and a magnetic disc assembly mounted on said tube and being operatively connected to move said trip rod independently of said magnet assembly,
• said disc assembly including a metallic disc positioned adjacent said sensing strip to respond to an increase in flux density of said primary circuit in response to high fault current in said primary circuit.