Improvements in, or relating to, thermally-operated tripping devices for use in connection with automatic circuit breakers and similar electrical switchgear

摘要

502,052. Electrically - released switches. CRABTREE & CO., Ltd. J. A. (Schiele Industriewerke) Nov. 13, 1937, No. 31211. [Class 38 (v)] An overload release unit comprising a box or container divided into trip chambers, each containing a thermally - sensitive element operative on a common trip bar, is provided with adjustable devices adapted to be operated from outside the box or container without removing the cover thereof, each device being adapted for causing displacement of a thermal element towards or away from the direction of its thermal expansion. Thus any one of the elements can be calibrated individually and independently of the others. As shown, a screw 13 passing through a wall of one, 3, of a number of trip chambers 2.. 4, bears on an inclined surface of a flexible metal strip 11 to which one end of the bimetal element 10 is secured, the other end engaging in an aperture of a trip bar 7 common to all the chambers, so that operation of the screw varies the position of the free end of the strip 10 in the aperture. A heater coil 8 is located within and connected at one end to, each element 10 and connected at the other end to a terminal 9, a terminal 12 being also connected, to strip 11 so that the element 10 is heated directly by the current and indirectly by the coil 8.