GB656499A - Improvements in and relating to electric frequency transformation systems - Google Patents

Abstract

656,499. Frequency changing. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 5, 1948, No. 25970. Convention date, Oct. 18, 1947. [Class 38 (ii)] [Also in Group XL (c)] A frequency transforming system comprises a saturable reactor 8 energized from an A.C. supply 1 saturating during opposite phase peaks of the latter, and applying impulses to a resonant circuit 3 tuned to a harmonic of the applied frequency, coupled with a load circuit, and simultaneously with the impulses a previously-charged condenser 5 discharges through the saturable reactor 8 to increase the impulsing effect. The condenser is charged through a phase-shifting circuit 11 for advancing and retarding the charging of condenser 5 for opposite phases of the A.C. input and comprising an adjustable self or other saturable reactor 12, in series with the condenser 5 through a choke 6. A shunt condenser 16 and inductance 17 in series of net capacitive reactance greater than the inductive reactance of the impulse circuit maintains substantially constant the output impulse voltage with change of phase due to circuit 11, and choke 6 suppresses interaction of the impulse circuit with the supply. The phase displacement between pulses is adjustable by varying the D.C. current through the reactor 8. A three-phase A.C. supply may be used, each phase operating independently as above and applying pulses sequentially to a common tuned circuit, and a switch may be used to reverse the phase of the pulses from one phase circuit, applying them across a tapping on the tuned circuit, so that together with the use of the pulse phasing means the resonant circuit may be tuned to any multiple of the supply frequency and not necessarily a multiple of three.