GB1238015A - - Google Patents

Abstract

1,238,015. Automatic tuning control. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 11 Sept., 1968 [28 July, 1967], No. 34807/67. Heading H3A. [Also in Division H2] A pair of static switching devices connected in parallel opposition are operated by sensing means automatically, in response to a circuit condition change, to control at least one reactive component of an impedance system, including at least one capacitor and at least one inductance, to vary the effective reactance rapidly, e.g. for network protection, current limitation, or selective frequency filtering in conjunction with rectifiers or inverters, the switch pair shunting a respective inductance or capacitor. The switching devices are thyristors or ionic valve devices of the mercury arc and thyratron kind. The sensing means are responsive to current, or voltage, or frequency values of a network, or temperature values of components, to operate the switching devices. A series resonance circuit, Fig. 1, is automatically detuned for current limitation by operation of one or more electronic switch pairs EL1-EL4 when a fault occurs. Conventional detectors or measuring devices or sensing means SU responsive to frequency variations of the networks connected to terminals T1, T2, control via unit FU the switches EL1-EL4 to maintain series resonance automatically when network frequency deviates from a normal value. Electronic switches EL1<SP>1</SP>-EL6<SP>1</SP>, Fig. 2 (not shown), can be in series with some of the reactive components of a normally series resonant coupling circuit and in shunt with others. When the inductive component is a main choke L1, Fig. 5, on uncontrolled winding portion L2, and controlled auxiliary chokes or winding portions L3, L4, sensing means (not shown) operate to connect portions L3, L4 in series aiding or series opposing relation to portion L2, or may shunt one or other portion L3, L4, using inversely parallel connected controlled rectifiers such as RP1-RP4 for selective control. Other applications include a filter circuit, Fig. 6 (not shown), for which a desired tuning is maintained. Reference has been directed by the Comptroller to Specifications 1,108,784 and 1,123,047.