Toroidal Coil in Measuring Alternating Current at a Distance


This article discusses the use of a toroidal coil in measuring alternating current from a straight current-carrying wire passing perpendicularly through the coil. The sinusoidally oscillating current generates a sinusoidally oscillating magnetic field in its vicinity. This, in turn, induces a sinusoidally oscillating emf in the toroid. This (measured) emf can be used in order to calculate the magnitude of the electric current in the wire. The use of such technique might be sensitive to the location of the point at which the wire passes through the toroid. If the location is not known very precisely, this might cause errors in the value of the calculated current. We wanted to study if the result does not depend on the location of the wire at all, as is usually stated, or not. The study was done by deriving a single analytical formula for finding out the calculated current with the wire passing through any given point inside the toroid. This formula was then solved at more than 2300 points inside a toroid to see if the location of the wire affects the result or not.

Share and Cite:

Mäkinen, S. (2014) Toroidal Coil in Measuring Alternating Current at a Distance. Journal of Electromagnetic Analysis and Applications, 6, 367-371. doi: 10.4236/jemaa.2014.612037.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Krishnamurthy, K.A. and Raghuveer, M.R. (2001) Electrical, Electronics and Computer Engineering for Scientists and Engineers. 2nd Edition, New Age International Publishers, New Delhi.
[2] Ward, D.A. and Exon, J.La.T. (1993) Using Rogowski Coils for Transient Current Measurements. Engineering Science and Educational Journal, 2, 105-113.
[3] Chattock, A.P. (1887) On a Magnetic Potentiometer. Philosophical Magazine, 24, 94-96.
[4] Rogowski, W. and Steinhaus, W. (1912) Die Messung der Magnetischen Spannung. Archiv für Elektrotechnik, 1, 141-150.
[5] Luciano, B., Batista, T., Freire, R., Guerra, F. and de Castro, W. (2012) Current Transformers with Nanocrystalline Alloy Toroidal Core: Analytical, Computational and Experimental Studies. Materials Research, 15, 805-808.

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.