GB699832A - Improvements in or relating to apparatus for indicating phase relationship between electrical quantities - Google Patents

Abstract

699,832. Phase-difference measurements. GENERAL ELECTRIC CO., Ltd., and BRYDEN, J. E. March 26, 1952 [April 3, 1951], No. 7710/51. Class 37. The phase relationship between two quantities which may be at points physically separated from each other is determined at a third point by means including a phase discriminator and an automatically adjusted phase changer. Apparatus is shown for indicating the phase relationship between voltages at points 1, 2 at a third point 3. A signal from the point 1 is transmitted through a path 4, such as a land line, or one of the channels, of a carrier transmission system, to a cathode follower valve 20 with a centre-tapped output transformer. The two output voltages are added to a voltage of adjustable phase from a potential divider 33 supplied by six secondary windings of a 3-phase transformer and driven by a motor 48. The combined voltages after rectification and smoothing are fed respectively to cathodefollower valves 33, 34, the outputs of which act on motor 48 which accordingly adjusts the potential divider 33 until the phase of the voltage supplied by it is in quadrature with the voltages from transformer 23. The position of 33 is then a measure of the phase of the voltage at 1. A potential divider 133 is similarly controlled to give the phase of a voltage at 2 and a differential arrangement 60 shows the phase difference. If the voltages at 1 and 2 agree in phase with the voltage and current at the same point, the device 60 indicates power factor. Reference is - made to the use as an alternative of a phase discriminator described in Specification 694,887.