GB513754A - Improvements in or relating to apparatus for the measurement of electrical reactance - Google Patents

Abstract

513,754. Inductance and capacitance measurements. WAYMOUTH, H., and WAYMOUTH GAUGES & INSTRUMENTS, Ltd. April 19, 1938, No. 11787. [Class 37] Apparatus for measuring a reactance value comprises an oscillation generator connected to a filter circuit having a sloping frequencyamplitude characteristic over the measuring range, a variable reactance in the generator or filter circuit, means for connecting the reactance to be measured in the oscillator or filter circuit, and an indicator in the output circuit of the filter that adjusts the variable reactance to re-establish the frequency relationship. The generator frequency can be at or above the cutoff value of the filter when the measured reactance is in the generator circuit, or the reactance to be measured can vary the cut-off value. The galvanometer control can act upon either the generator or filter circuits. In Fig. 5, the reactance 14 to be measured is connected in the generator circuit, the frequency of which is normally above that of the cut-off value of filter 27...29. During measurement, the filter passes current to valve 31, the instrument coil 55, Fig. 6, being deflected and varying the position of a core 52 in coil 11 that forms part of the oscillatory circuit. This movement restores the frequency relationship between the filter and generator, and the pointer 54, when at rest gives a measure of the reactance 14. The core 52 is of powdered material and can have a variable cross-section to widen the scale graduations at one end. The turns of the coil 11 can be spaced to produce a similar scale effect, or a fixed condenser can be located in series with the coil for the same purpose. Specifications 353,482 and 465,787, [Group XXXVIII], are referred to.