Two-Stage Coaxial Inductive Voltage Divider and Its Calibration Setup for Use Between 1 and 100 kHz

Abstract

This paper describes the development of a compact n/8 inductive voltage divider (IVD) for the use in the frequency range between 1 and 100 kHz and voltages up to 5 V. The development includes a number of additional inductive components for the bootstrap calibration setup such as a supply transformer which ensures the galvanic isolation of the calibration setup, a calibration transformer, and a detection transformer. 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. The bootstrap calibration setup follows a special coaxial-by-design scheme, which guarantees nearly identical currents in inner and outer conductors of the coaxial connections without use of any chokes. The calibration of the IVD yielded in-phase and quadrature IVD corrections within $6 \cdot {10}^{-6}$ and $1 \cdot {10}^{-6}$ both with uncertainties ( $k=2$ ) below 1 $\cdot {10}^{-6}$ at 100 kHz.