Calibration of a two-stage coaxial inductive voltage divider for use between 1 kHz and 100 kHz

This paper describes the development of a compact inductive voltage divider (IVD) setup and its calibration in the frequency range between 1 kHz and 100 kHz and voltages up to 5V. The desired frequency and uncertainty range requires a two-stage IVD design with coaxial windings, a triaxial differential branch, and voltage controlled shields to minimize capacitive stray currents and the corresponding errors. The calibration was carried out with help of the bootstrap method in a special “coaxial-by-design” setup which guarantees nearly identical currents in inner and outer conductors of the coaxial connections without use of any chokes. This measurement setup principle required the development of special inductive components such as a supply transformer which ensures the galvanic isolation of the calibration setup, a calibration transformer, and a detection transformer. First calibration measurements indicate in-phase and quadrature IVD corrections within 6·10^-6 and 1·10^-6 both with uncertainties (k = 2) below 1·10^-6 at 100 kHz.