Dielectric Loss Measurements Parallel to Laminations

Laminated material is often used as insulation in an electrical device in such a way that a large component of the dielectric field passes through it parallel to its laminations. In present test methods dielectric loss measurements are made on such material with the dielectric field passing through it perpendicular to its lamination. It is evident that the two conditions are different and the dielectric losses as measured by test are not the same as exist when in use. This paper presents a test method by which power factor, dielectric constant and dielectric loss factor of laminated insulating materials can be measured with the dielectric field parallel to the laminations. Results of measurements made with the dielectric field parallel to laminations of both unconditioned and conditioned specimens are compared, respectively, with results obtained with the field perpendicular to laminations.