GB730346A - Improvements in electric circuit-breaker devices - Google Patents

Abstract

730,346. Protective cut-out arrangements; conducting liquid switches; controllers. BENCHEMOUL, N. R. May 4, 1953 [May 7, 1952], No. 12350/53. Classes 38 (3) and 38 (5). In a circuit-breaking arrangement for an apparatus 1, Fig. 1, supplied from terminals 2, the increase of resistance of a liquid resistance apparatus 3 in the event of excess current conditions causes a drop in the voltage across the winding 14 of a circuit-breaker 15 which opens to interrupt the supply. The apparatus 3 comprises a small chamber 7 enclosing electrodes 4, 5 and communicating via small passages 8, 9 with a vessel 10, the chamber and vessel being filled with conducting liquid. Under normal conditions, the heat evolved by the current passing through the liquid in the chamber 7 is dissipated by the circulation of liquid through the passages, but under heavy overload conditions, the liquid in the chamber 7 is vaporized and the resulting considerable increase in resistance causes the drop in voltage across the winding 14 and reduces the current flowing in the circuit so that circuit-breaker does not have to interrupt the full overload current. Under moderate overload conditions the slow vaporization of the liquid may result in an alternate rise and fall in the resistance of the apparatus 3 without causing the opening of the circuit-breaker 15. This condition may be indicated by an incandescent lamp 43 in series with the winding 14 or by a discharge lamp 44 in series with a resistance 45. A low resistance 46 may be connected across the circuit on the operation of a press-button switch 47 to cause the opening of the circuit-breaker. The circuitbreaker 15 may be closed by depressing a pushbutton 17 or by suitable electromagnetic means. In a modification, Fig. 4, the apparatus 3 may be housed within the container 18 of a motor starting liquid rheostat 19 which has a movable rotor 20 with interconnected electrode sectors 25, enclosed in a fixed casing which has electrode sectors 27. In this modified arrangement the apparatus 3 not only causes the opening of the circuit-breaker under overload conditions as described above, but also in the event of the liquid in the container 18 reaching too low a level or too high a temperature. In a polyphase arrangement, Fig. 7 (not shown), two (or more) superposed chambers 7 may be provided in a common vessel and have Intercommunicating passages so that any vapour produced rises to the uppermost chamber. Fig. 9 (not shown) illustrates a two-phase four-wire arrangement. Specification 718,320 is referred to.