GB523956A - Improvements in and relating to the control of automatic electric switching devices - Google Patents

Abstract

523,956. Electric circuit-breakers. AKT.-GES. BROWN, BOVERI, & CIE. Jan. 16, 1939, No. 1479. Convention date, Jan. 14, 1938. [Class 38 (v)] A power switch operated by compressed gas works in combination with an isolating switch in such manner that after automatic opening of the power switch automatic reclosing if the overload persists takes place twice or oftener within a set period or until the isolating switch is open. In Fig. 1 a power switch a with isolating switch b is operated by means of compressed air in the container c. On manual operation at switch i the circuit is closed through the relay sp2 and switch o3. Energization of sp2 opens valve n, admitting compressed air from c by way of m' to operate piston k, in slide k thus closing the contacts at o, and connecting m2 to m5 by way of k. Closing of o1 closes the circuit by way of q2 and o3 through relay sp, which operates valve d admitting pressure gas to e thus opening valve f and opening the power switch. Pressure gas from behind f passes by way of m, to q, making a holding circuit for relay sp1 and by way of k and m5 to means g for operating isolating switch. This opens o3 by which all other parts of the circuit return to normal. On operation of protective relay b the circuit is connected by way of q2 and o, through relay sp, which as before opens the power switch and admits pressure gas to k by way of m2. Since k, is in its initial position, the pressure gas passes through m4 to chamber p, where pressure builds up to open valve P11and then passes by way of m3 to close power switch a, to operate q2 so as to transfer the protective relay circuit to sp2, and to chamber P2. q, has meanwhile maintained a holding circuit for sp,. If, on closing a the protective relay h does not operate again the pressure accumulating in p2 operates after a time lag to open the holding circuit for sp1 and to vent the system by way of m22, m, and opening r2. If h does operate on closing a, sp2 is energized opening n and moving k, so that pressure gas from m2 is transferred from m4 to m5 and pressure is allowed to escape from m3 by way of m33, k1 and opening r3. Thus a is reopened, for abutment k3 maintains k2 so as to keep o2 closed, and g is operated. As before the opening of g breaks circuit at o3, and the system is returned to initial position.