Hysteresis-free current sensor - has soft magnetic core for coupling prim. and sec. coils, generator for periodically magnetising to positive and negative saturation and sample=and=hold circuit for acquiring sec. current to form average voltage drop

• Main Author: KNUTH, DETLEF, .., 6670 ST INGBERT, DE
• Format: Patent
• Language: English; German
• Published: 10.03.1994
• Edition: 5
• Subjects: MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

The current sensor has an unslotted magnetically-soft core, a primary coil (1) carrying the measurement current, and a secondary coil (2) coupled with the primary via the core. A circuit is provided for the periodic magnetisation of the core to saturation, and a sample and hold circuit (4) which detects and stores a voltage drop proportional to the secondary current and a stage which forms the mean of two voltage drop measurements. The voltage sampling frequency is at least three times the frequency of the measurement current and the core magnetisation system is a bridge circuit generator. USE/ADVANTAGE - For measuring a.c. and d.c. currents. Measurement errors caused by hysteresis of magnetic core are eliminated using device having small dimensions achieved.