Abstract :
IN the late 1920´s, the increasing demand for fast-clearing circuit breakers brought forth the development of various types of modern arc-rupturing devices. Among others, there was developed the pulsion-chamber arc-rupturing device1 which now is in satisfactory operation in thousands of breakers. The theory of expulsion action and the performance of the expulsion-chamber breakers have been reported on frequently. Test on a 115-kv system showed arcing times of approximately 1 1/2 cycles at short-circuit capacities ranging up to 1,650,000 kva.1 Tests on a 230-kv system showed arcing times of approximately 2.5 cycles at ratings up to 1,125,000 kva.2 In the middle 1930´s the practice of high-speed reclosing was introduced and is now widely accepted. Interrupting capacity tests performed on a 69-kv system showed that the expulsion-chamber arc-rupturing devices gave excellent performance in conjunction with high-speed-reclosing operation.3 Following the demand for still shorter opening time, more recently five-cycle breakers have come into wide use. On highest voltages, particularly in conjunction with switching of long lines, the use of three-cycle breakers frequently is indicated.
