Calibration of 10∶−1 inductive voltage dividers by Thompson´s method using an electronically-enhanced three-stage calibrating transformer

This paper describes the calibration of 10:-1 inductive voltage dividers at power frequencies using Thompson´s method. It also describes an electronically-enhanced three-stage 10:-1 inductive voltage divider (IVD) with an additional, secondary winding, used as a calibrating transformer. The correction circuitry was designed to further reduce the calibrating transformer magnetic error and is isolated from the input and output voltages. To define open-circuit voltage at IVD and calibrating transformer outputs, a BNC connector was modified with an additional electrode and used as part of the special socket with a switch. The calibration system was applied to the calibration of two two-stage IVDs.