GB565843A - Improvements in and relating to apparatus for starting and controlling electric discharge devices - Google Patents

Abstract

565,843. Supply and control systems for space discharge devices. BRITISH THOMSON-HOUSTON CO., Ltd. April 14, 1943, Nos. 5964 and 5965. Convention dates, April 21, 1942. [Class 38 (iv)] A pair of electric discharge devices, such as fluorescent lamps 1, 2, are run in series and with circuit arrangements whereby adequate starting voltage is provided for each in turn. A reactive ballast impedance, such as 6, Fig. 1, is connected in series with both, and in shunt with that one which is not connected to the first impedance is connected a reactive circuit 12 having a reactive character different from that of the first impedance. Thus, voltages in opposed phase are initially produced across the discharge device 1 sufficient to start it, and the circuit in shunt to the second device 2 then develops sufficient voltage to start it also. When the supply voltage is not sufficient to run the lamps in series, a transformer, such as 5, is used to step up the supply voltage. When the ballast impedance is inductive, power factor correction may be obtained by a condenser 7 and when capacitive an inductance may be connected across the primary winding of the transformer. An auxiliary transformer winding may inject a voltage of the required phase into the shunt circuit. Two series pairs of lamps may be run in parallel, one part having predominantly capacitive ballast and the other predominantly inductive ballast. Fig. 6 shows a transformer with a secondary winding 33 stepping up the voltage for the series circuit, a magnetic shunt being provided between it and the primary winding 30. The limb 31 has a bridged gap 36 between the winding 33 and a winding 34 adapted to induce a voltage in correct phase in the shunt circuit containing inductive impedance 37, the series circuit containing capacitive impedance 38.