Patent GB-468431-A (GB)
Title: Improvements in electric supply systems
IPC: H02P9/32
Filed: 1935-10-28
Abstract: 468,431. Rectifying alternating currents; automatic control systems ; supply systems. MARTIN, J. L. P. G. Oct. 28, 1935, No. 29713. Convention date, April 4, 1935. [A Specification was laid open to inspection under Sect. 91 of the Acts, April 30, 1936.] [Classes 38 (ii) and 38 (iv)] Arcs; illumination.-In the supply of D.C. to a carbon arc the current through and voltage across the arc are arranged to saturate separate chokes in the A.C. supply to a rectifier, the output of which is arranged to control the D.C. voltage supplied to the arc so as to maintain optimum current and voltage conditions. In one arrangement a D.C. generator 2 supplies the arc 1 and has its field winding 3 supplied from a rectifier 615 in the input circuit of which are connected two chokes 613, 614 having saturating windings 617, 618 connected across the arc and in series with it respectively. Compensation for variations in the A.C. supply voltage is obtained by additional saturating windings 621, 620 on the chokes 614, 613 these windings being supplied from the A.C. mains through a rectifier 619. In a modification, Fig. 2, a series motor 632 is connected in series with the supply to the arc to give a bucking voltage and a separate field winding 636 on the motor is energized through a rectifier 635 from A.C. mains through two chokes 634, 633 saturated in accordance with the voltage across and current in the arc respectively. In a further modification the arc is supplied from A.C. mains through a rectifier, and a choke in series in the supply to the rectifier is saturated with D.C. from a rectifier which is supplied with A.C. through two chokes, one saturated in accordance with the current in the arc and the other in response to the voltage across it. Additional saturating windings on these chokes may be supplied from a unit controlled in response to the illumination from the arc so as to keep its brilliance constant. The Specification as open to inspection under Sect. 91, described the following arrangements : (1) the control of the D.C. supply to an arc by means of a single choke saturated in accordance with voltage and current conditions of the arc, the choke being arranged in the circuit of a rectifier supplying the arc or supplying excitation current to a generator supplying the arc; (2) a polyphase gridcontrolled mercury arc rectifier supplying a carbon arc is supplied with A.C. grid potentials through chokes saturated in accordance with the voltage across the arc ; (3) the excitation of a D.C. generator supplying an arc is obtained from two Graetz connected rectifiers the output circuits of which are in series, and the input circuits being controlled respectively by chokes one of which is saturated in accordance with the voltage and the other in accordance with the current conditions in the arc ; (4) four chokes in series with resistances are connected to form a bridge supplied with A.C., the output diagonal including a transformer and rectifier for supplying current to the field winding of a D.C. generator supplying an arc. The chokes in opposite sides are saturated in accordance with voltage and current conditions in the arc whereby unbalance of the bridge and control are effected ; (5) a rectifier supplying an arc is controlled by a series choke saturated with current through a rectifier from the output diagonal of an A.C. bridge composed of two inductances and two resistances. The inductances are saturated in accordance with voltage and current conditions in the arc respectively ; (6) two D.C. generators supply a load in parallel and the excitation of one of the generators is obtained through a rectifier from an A.C. bridge comprising two chokes and two resistances, the chokes being saturated in accordance with the voltage and current conditions of the load circuit respectively ; (7) two arcs are connected, each through a separate resistance, in parallel with a D.C. generator the excitation of which is obtained through a rectifier from an A.C. bridge including two inductances of which one is saturable in accordance with the total current from the generator and the other in accordance with the generator voltage and the p.d. across each of the series resistances. The series resistances may be short circuited during normal operation ; (8) the excitation of a D.C. generator supplying an arc is obtained through a rectifier from an A.C. bridge composed of two chokes and two resistances, the chokes being saturated in accordance with voltage and current conditions respectively of the arc and that supplied from across the arc having a series resistance which is short circuited by a switch responsive to arc current. This subject-matter does not appear in the Specification as accepted.