Eddy Current Loss

Eddy current loss, also called joule loss or resistive loss, refers to the power dissipated in a conductor as a result of eddy currents induced by a changing magnetic field.  When a conductor is exposed to a varying magnetic field, such as in the presence of alternating current or a moving magnet, circulating currents called eddy currents are induced within the conductor.  These currents encounter resistance within the conductor material, leading to the conversion of electrical energy into heat energy.

Eddy current loss is proportional to several factors, including the frequency of the changing magnetic field, the magnitude of the magnetic field, the electrical conductivity and resistivity of the conductor material, and the geometry of the conductor.  This loss can be significant in electrical devices such as transformers, motors, generators, and inductive heating systems, where alternating currents or varying magnetic fields are present.

Engineers take measures to minimize eddy current losses in electrical systems, such as using materials with lower electrical conductivity, laminating conductive materials to reduce the formation of large eddy currents, or employing specialized winding techniques.  Minimizing eddy current loss helps improve the efficiency and performance of electrical devices.

This formula provides an approximation of the eddy current losses in a homogeneous conductor under ideal conditions.  However, in practical applications, factors such as the geometry of the conductor, the distribution of the magnetic field, and the presence of other materials nearby may affect the actual eddy current losses.  Therefore, this formula serves as a starting point for estimating eddy current heat loss and may require adjustments or considerations based on specific engineering requirements and conditions.

 

Eddy Current Loss formula
\( P_e \;=\; K_e \; f^2 \;  \Phi_B^2 \; t^2 \; V \)
Symbol	English	Metric
\( P_e \)  = eddy current loss	-	\(N-m\)
\( K_e \) = eddy current constant	\(dimensionless\)
\( f \) = frequency of the alternating current	-	\(s^{-1}\)
\( \Phi_B \)  (Greek symbol Phi) = maximum flux density	-	\(T\)
\( t \) = thickness of the conductor	-	\(m\)
\( V \) = volume of the material	-	\(m^3\)