Non-Contact Current Measurement for Three-Phase Rectangular Busbars Using TMR Sensors

Area of Science:

• Electrical Engineering
• Sensor Technology
• Power Systems

Background:

• Accurate current measurement is crucial for power system monitoring and control.
• Existing non-contact methods often face limitations in dynamic range, bandwidth, or installation complexity.
• Three-phase rectangular busbars require specialized non-contact sensing solutions.

Purpose of the Study:

• To develop and validate a novel non-contact current measurement method for three-phase rectangular busbars.
• To utilize the advantages of tunneling magneto-resistance (TMR) sensors for enhanced measurement performance.
• To achieve accurate and reliable online calibration of the current sensor system.

Main Methods:

• A non-contact current sensor array using three TMR sensors was designed and positioned near busbars.
• A thyristor-controlled resistive load was employed for generating identifiable calibration currents.
• A robust method was developed to extract voltage components from TMR sensor signals for calibration.
• A complete measurement system integrating the TMR sensor, calibrator, and data acquisition was implemented.

Main Results:

• The developed system demonstrated a relative RMS error of less than 2.5% and a phase error of less than 1° compared to a commercial probe.
• Nonlinearity error of the TMR-based current sensor was found to be better than 0.8%.
• The proposed online calibration method proved effective in establishing accurate current-to-magnetic field relationships.

Conclusions:

• The proposed non-contact current measurement method using TMR sensors is accurate and reliable for three-phase rectangular busbars.
• The system's performance, including low error margins and effective online calibration, makes it suitable for practical power distribution applications.
• TMR sensors offer a viable solution for non-contact current sensing due to their favorable characteristics.