GB622130A - Improvements in or relating to bridge type electrical measuring apparatus - Google Patents

Abstract

622,130. Inductance, capacitance, and resistance measurements. WAYNE KERR LABORATORIES, Ltd., and CALVERT, R. Oct. 11, 1946, No. 30445. [Class 37] In an A.C. bridge A, B, C, D in which the potential developed across the arm A, B is adjusted to balance the bridge by means of a shunted potentiometer 15, the latter is coupled to the adjacent arm B, C by a tapped transformer or auto-transformer 18. In the arrangement shown in Fig. 1 for measuring a resistance 23, the arm A, B comprises the upper half of the secondary of a transformer 11, arm C, D is constituted by a standard resistor 26, and arm A, D by a selected portion of the lower half of the secondary of transformer 11. The value of the resistance 23 is given by multiplying the setting of the potentiometer at balance by a factor determined by the tappings on the transformers. The potentiometer may be connected to an intermediate point on the autotransformer. In a modification, Fig. 3, for measuring an inductance 30, the standard impedance is a capacitor 32 connected as shown and a resistor 33, the setting of which indicates the Q of the inductance, is adjusted to complete the balance. In another modification, Fig. 4 (not shown), for measuring capacitance, the unknown impedance forms the arm C, D and a standard capacitor shunted by an adjustable resistor forms arm B, C.