US Patent 7301434 Thermally responsive electrical switch

A motor protector (10) is shown having an elongated generally cup-shaped metallic housing (12) formed by a top wall (12a) and a side wall (12b) extending down from the perimeter of the top walls, the free end of which is welded to a header (14). The side and top wall have a rounded junction (12c) and a calibration rill (12e) is formed in the top wall from one end of the housing and through the rounded junction. An elongated thermostatic disc (16) is mounted in the housing and has a movable electrical contact (20) mounted at one end to be movable into and out of engagement with a stationary electrical contact (34) that is in turn mounted on a heater (26). A ceramic insulator plate (32) is interposed between the heater and the header.