GB400191A - Improvements in and relating to electrical apparatus for the detection or measurement of phase differences or for both purposes - Google Patents

Abstract

400,191. Phase-difference measurements. TAYLOR, M. K. and FERRANTI, Ltd., Hollinwood, Lancashire. Jan. 13, 1932, No. 20243/33. Divided on 399,845. [Class 37.] Apparatus for the detection or measurement of phase differences between, for example, alternating current generators x, y, and mains z, includes a pentode l<1> to the control grids p, q of which the voltages to be compared are applied through transformers having primary windings e, f and secondary windings g, h. The grids p, q are so biassed that the anode current is substantially zero except when both grids are positive with respect to the bias value. A voltmeter u indicates when there is a voltage on the line z, a milliammeter v in the anode circuit of the pentode l<1> then indicating by a maximum reading the point at which the generator x or y being examined is in phase with this voltage. The apparatus may be employed for determining the phase difference between electrical oscillations, which may be amplified before application to the primary windings e, f. The pentode may be replaced by any other thermionic device having more than four electrodes in which the rate of change of anode current with change of anode voltage is positive or zero over the working range so that only one value of voltage corresponds to any given value of current. The instrument may be employed in connection with the balancing apparatus described in Specification 399,845.