Electrical Machines Laminations Magnetic Properties: A Virtual Instrument Laboratory

Undergraduate courses in electrical machines often include an introduction to their magnetic circuits and to the various magnetic materials used in their construction and their properties. The students must learn to be able to recognize and compare the permeability, saturation, and losses of these magnetic materials, relate each material to its specific properties, and understand the impact of these properties on the major performance metrics of electrical machines. This paper describes a new test equipment setup and lab guide that helps students achieve these learning goals. The test equipment consists of two transformers of grain-oriented and non-grain-oriented electrical steel, transducers, a data acquisition (DAQ) board and a PC-based virtual instrument. The virtual instrument shows voltage, current, and core flux time waveforms, the rms voltage versus current curves and, most importantly, the lamination material magnetic cycle. Students´ laboratory work was organized into a series of experiments that guide their achievement of these magnetic materials-related abilities. Pre- and post-lab exams assessed student learning, which was shown to have increased significantly. Students´ opinions of the relevance, usefulness, and motivational effect of the laboratory were also positive.