Abstract
Inductive voltage dividers (IVDs) are widely used in the field of AC measurements, such as impedance measurements at audio frequencies. Two-stage guarded IVD has been developed by D N. Homan and T L. Zapf about forty years ago. However, it is not easy to construct the two-stage guarded IVD. Therefore, we have developed a two-stage IVD using special winding method without guard by magnetic and electrical shield. To reduce admittances of each winding wires, corrugated cardboard of polypropylene is used for new two-stage IVD. In addition, ratio winding and excitation winding were wound toroidally around two FINEMET ring cores using PEW flat cable 0.7 mm in diameter. As a result, the in-phase ratio errors are within ±6.1×10-8 of the input at frequency 1kHz or less. In this report, the winding methods and measurement results of new two-stage IVD are described.
