GB277929A - Method of or means for reducing the voltage drop in rectifiers - Google Patents

Abstract

277,929. Meyer, F., and Spanner, H. J. Sept. 24, 1926, [Convention date]. Vapour and low-pressure apparatus, arrangements of.- The voltage drop in rectifiers, normally equal to a mean value between the striking voltage at which the arc starts in each half-wave and the lower cut-off voltage at which the arc fails, is reduced by superposing an auxiliary high-frequency voltage on the main voltage to be rectified so that the striking voltage is reached or exceeded at the electrodes at or shortly after the moment when the main voltage passes through a value equal to the cut-off voltage. The arc thus strikes earlier in each halfwave and when the arc strikes the auxiliary voltage falls to a negligible value for the rest of the half-wave. The voltage drop is thus reduced to the cut-off voltage, for example, to 5-10 volts. Rectifiers of the mercury-vapour or incandescentcathode, gas-filled types and insulating tubes around the cold electrodes to prevent reverse discharges and discharges between the cold electrodes are referred to. The rectifier preferably utilizes the shielding effect of electrodes at a distance apart equal to the mean free electrode path as described in Specifications 274,026 and 275,550, [both in Class 39 (i), Electric lamps, Arc &c.]. In rectifying low-frequency current from a transformer T<1> by a double anode, incandescent cathode device U feeding a direct current circuit 0, a high-frequency source of high impedance relative to the resistance of the arc in the device U is coupled to a transformer T<2> and is effectively short-circuited by the arc when this strikes. Shunting condensers C<1>, C<2> are arranged as shown. The Specification as open to inspection under Sect. 91 (3) (a) comprises also an auxiliary direct voltage superposed on high-frequency voltages to be rectified. This subject-matter does not appear in the Specification as accepted.