Patent GB-455117-A (GB)
Title: Improvements in or relating to electric measuring instruments
IPC: G01R15/00
Filed: 1935-12-23
Abstract: 455,117. Current and pressure meters; current duration meters. IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London.-(Assignees of Stansbury, C., and Simon, A. ; 315N, 12th Street, Milwaukee, Wisconsin, U.S.A.) Dec. 23, 1935, No. 35567. Convention date, Jan. 2. [Class 37] Apparatus for measuring a characteristic quantity of an electric impulse of short duration comprises a measuring circuit including a glow discharge tube which lights up on the application of a given voltage, means for impressing a voltage which is a function of said quantity upon said circuit in response to an impulse, and means for impressing a portion of said voltage substantially equal to the emission voltage on the tube, the latter means being calibrated to indicate directly the magnitude of the quantity. In the arrangement shown in Fig. 1, the magnitude, voltage and duration of impulses applied to welding electrodes 6 is indicated by glow tubes 1, 2 and 3 respectively. The tube 1 is supplied from the secondary winding 4a of a current transformer 4 through a potentiometer 9 and resistances 8, 10. The resistance 8 is normally short-circuited by the contacts 11a of a push button switch 11, but can be inserted in the circuit by depressing the button. The movable arm of the potentiometer 9 is so adjusted that the tube 1 is dark when the push-button is depressed and lights up when the push-button is released, the position of the arm is then a measure of the current in the transformer 4. The voltage across the welding electrodes 6 is determined in a similar manner by the tube 2, which is connected to the secondary winding 12b of a voltage transformer 12 through a potentiometer 14 and resistances 13, 15, the resistance 13 being normally short-circuited by the contacts 11b of the push-button switch. The primary winding 12a of the transformer 12 is provided with tappings for different voltage ranges. The duration of the welding current is deter. mined by causing it to charge a condenser 32 to a voltage just sufficient to light the tube 3. For this purpose, current is supplied from a potentiometer 17, with tappings to suit different line voltages, to one diagonal of a rectifier bridge, the other diagonal of which includes a resistance 26 and two glow tubes 27, 28. The timing condenser 32 is connected across these glow tubes through a resistance 30 and the arm of a potentiometer 31, but is normally short-circuited by the contacts 34b of a relay 34. When the line switch is closed, the relay is energized and the condenser is charged, the voltage which it attains in a given time interval being dependant on the position of the potentiometer arm. A portion of the resistance 30 is normally short-circuited by the contacts 11c of the push-button switch 11. The glow tube 3 is connected across the terminals of the condenser 32 through a resistance 33. In a modification, Fig. 2 (not shown), each of the glow tubes 1 ... 3 is replaced by a pair of tubes one of which is arranged to light up while the other remains dark when the potentiometers are correctly adjusted, the push button switch being dispensed with.