A novel coreless current sensing mechanism for two-wire power cord

In the development of smart home products, energy monitoring, and control systems, there is a significant need for precise and reliable electric current measurement. Most domestic appliances, whether residential or commercial, are powered by power cords with two wires. A reliable and accurate current probe would be required to detect current in two-wire power cables. Existing current sensors for two-wire power cables are complex, bulky (they use a magnetic core), and need full access to the power cord. In this paper a coreless, contactless current probe that requires only limited access of the space around the two-wire power cable is proposed. The sensor unit presented here measures the current accurately even for certain types of misalignments of the power cord. This makes the current measurement less sensitive to minor mechanical displacements, radius of the conductors, and the overall insulation thickness of power cord. In the proposed current probe, one-of-a-kind and highly reliable arrangement of magnetic field sensors, are used to measure the magnetic flux density caused by the current passing in the power cord. The current is computed using a derived mathematical formula which is expressed in terms of the voltage outputs of the magnetic sensors. To provide a clear understanding of the measurement process, an analysis using the Finite Element Method (FEM) is performed. The functionality of the proposed current probe is theoretically tested. Considering different sources of errors, an accuracy of less than 1.5% is obtained. [Display omitted] •The proposed current probe does not require 360° space around the power cord, this method requires only partial space by the side of the power cord.•The proposed probe enables distance-independent current measurement, varying based on power cord insulation thickness and diameter.•The probe offers efficient, simple, cost-effective current measurement in power cords with three magnetic sensors.•To keep up with the errors, mathematical analysis was done with finite length of the power cord.•In addition, FEM analysis validated in presence of ferromagnetic materials and with interference due to external magnetic field.