GB350789A - Improvements in apparatus for the measurement of capacitance and power factor of electrical condensers - Google Patents

Abstract

350,789. Capacitance and powerfactor measurements; sets of resistances ; inductances. CAMPBELL, A., Culmora, Girton Road, Cambridge. July 24, 1930, No. 22303. Addition to 317,642, [Class 37, Electricity, Measuring &c.]. [Class 37.] In the bridge for measuring capacitance and power factor forming the subject-matter of the parent Specification, a closed loop circuit A, Fig. 1, is coupled to both the primary and secondary circuits of the main mutual inductance M by auxiliary mutual inductances m, u, the resistance of the loop being adjustable to compensate for frequency and the adjustable coupling being arranged to indicate the power factor. The coupling coils m, u in the primary and secondary circuits may be made equal and fixed close together, as shown at F. G, Fig. 2, a single coupling coil D forming part of the loop circuit A being arranged to turn relatively to these coils and indicating power-factor directly on a scale. The mutual inductance between the coils F, G is balanced by coils F1, G1. In a modification, Fig. 3, in series with the mutual inductance M is a much smaller one m, across the primary coil of which is a resistance X variable by a slider, which indicates the power factor directly. The resistance. R, Figs. 1 and 3, is in the form of a conductance box shown in Fig. 4. A lower limit is set to the range of conductance, the minimum value being, for example, one hundredth of the maximum. The value of the conductance is varied by step switches a .. e or slide-wire rheostats arranged in series or parallel or series-parallel. Specification 294,053, [Class 37, Electricity, Measuring, &c.], is referred to.