Transformer-like devices for high-accuracy AC current measurements

Abstract

A theoretical and practical framework is presented to aid in the design, fabrication, and testing of transformer-like devices for use in high-accuracy ac current metering applications. Current transformers, two-stage current transformers, and current comparators are discussed, as well as related devices that use passive and active error correction techniques. Transformer theory is developed in terms of simple electromagnetic theory and practical equivalent circuits. Magnetic design equations are presented and the measurement of relevant magnetic properties is discussed. Sources of error and their mitigation are covered in detail, including errors caused by magnetizing currents, winding and core inhomogenieties (so-called magnetic errors), and circulating capacitive currents. Calibration methods and current transformer testing are also covered.

Characterization of AC-DC transfer shunts up to 100 A at 100 kHz using two-stage, amplifier-aided current transformers

“…They also have the inher providing good isolation and rejection of voltages developed across multiple current Most ordinary current transformers exhibit errors, which are critical functions of the o secondary burden, and frequency. However, t Souders [4,5] showed that amplifier-aided m transformers could achieve very high accu frequency range of 50 Hz to 10 kHz. Furtherm in ratio over a wide range of frequencies, i.…”