Thermally responsive electrical switch

摘要

A motor protector (10) is shown having an elongated generally cup-shaped metallic housing (12) formed by a top wall (12a) and side wall (12b) extending down from the perimeter of the top wall, 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. The calibration rill is formed with a rigid flat bottom wall (12m) and extends to a calibration ridge (12h) intermediate to the two elongated ends of the housing. An elongated thermostatic disc (16) has a ring shaped dished area (16a) deformed in the central portion of the disc. A first end of the disc is mounted on the inside surface of flat bottom wall (12m) with the calibration ridge (12h) aligned with the deformed area of the disc. A movable electrical contact (20) is mounted on the other end of the disc movable into and out of engagement with a stationary electrical contact (34) that is in turn mounted on a heater (26). The heater is attached at one end (26a) to a terminal pin (28) at a first segment (26c), is stepped down at a second segment (26d) away from the disc and has a third segment (26e) on which the heater is mounted. A ceramic insulator plate (32) is interposed between the heater and the header.