GB373047A - Improvements in and relating to protective apparatus for electric circuits - Google Patents

Abstract

373,047. Protective cut-out arrangements. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. -(Assignees of Belt, T. A. E.; 144, Waverly Place, Schenectady, New York, U.S.A.) Oct. 26, 1931, No. 29671. Convention date, Oct. 25, 1930. [Class 38 (v).] A circulating-current arrangement 12, 13 is used in parallel conductors containing impedances, for example and as shown, condensers 7 used for power-factor improvement across a system which may be fed from either machine 3, 4. On a predetermined degree of unbalance occurring, due to a breakdown of dielectric or other cause, the contactor 8 is opened by the coil 11 to cut out the condensers. If the condenser circuits are connected in series with the mains, a contactor is arranged to shortcircuit them on a fault occurring. The condensers are preferably all of equal capacity and a wattmetric indicator 18 and scale 19 are operated by a further current-unbalance coil 15 and a voltage coil 17, the reading depending on the magnitude and direction of out-of-balance current in 15, so that it can be easily seen how many condensers have broken down and in which circuit. In the limiting position, contacts 20, 21 are engaged to close the circuit to indicator lamps 22, 23 and/or alarms. Specification 286,693, [Class 38 (v), Electric switches &c.], is referred to.