Product Details
Ferromagnetic Hysteresis
Study the hysteresis plot for a ferromagnetic core in a transformer
Description
A varying magnetic field is generated in a transformer iron core by applying a triangle wave voltage to the primary coil. The magnetic flux density, B, is plotted versus the magnetic field strength, H. From this hysteresis plot, the value of B at saturation is determined, as well as the retentivity and coercivity of the ferromagnetic core.
To determine the magnetic flux density in the core, the voltage across the secondary coil is measured and plotted versus time. Using Faraday’s Law of Induction, the area under the voltage versus time curve is the integral of the induced emf, which is proportional to the magnetic flux density.
The magnetic field strength is determined by measuring the input current to the primary coil.
Students analyze the B versus H plot to find:
- The area inside the curve is a measure of the energy/volume lost per cycle.
- The retentivity is the amount of magnetic flux density that the material retains when there is no current in the coils.
- The coercivity is the amount of reverse magnetic field strength that is required to make the magnetic flux density zero again.
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