GB633597A - Improvements in electrical regulation systems - Google Patents

Abstract

633,597. Modifying reactive characteristics of electric circuits. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAG. Jan. 1, 1948, No. 41. Convention date, Jan. 11, 1947. [Class 38 (vi)] In order to reduce the time constant of a circuit including an inductive winding 1 which is performing a regulating function, there is connected in series therewith a highly evacuated electronic valve 2 having the characteristic of a pentode to the screen grid 11 of which a constant voltage 7 is applied, and the regulation is effected by altering the valve characteristic as by changing the voltage applied to the control electrode 8. If the control grid voltage be such as to establish the characteristic curve A shown in Fig. 2, where the current in the winding 1 has the value il and the potential across the valve is el, a sudden increase of control grid voltage to establish the characteristic A1 will immediately reduce the potential across the valve to e2, and the surplus voltage e1-e2 and the power represented by the area C is available to raise the current through the winding 1 at a rapid rate. A beam tetrode with a like characteristic may be used similalry. The time constant can be further reduced by connecting a condenser 6 and reactor 5 in series across a low cathode resistance 3 and connecting the grid voltage source as shown. The winding 1 may be, for example, the control winding of a saturable reactor or the exciting winding of a generator and the invention is applicable to the restoration of a variable quantity to a normal value or to the intentional change of the normal value of a quantity. A specific application mentioned is the strong and strictly time-determined variation of welding current by a small control power. If the current controlled by the pentode refuses smoothing, as when its source is a single-phase two-way rectifier, the characteristic of the pentode is such as to absorb the voltage pulses substantially without current variation.