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Unformatted text preview: Experiment V1 Ferromagnetic Core Characteristics Objective To observe the B-H hysteresis loop of a transformer iron core. Summary The magnetic characteristics of any material can be observed by applying an ac MMF excitation to the material. Ferromagnetic materials are often used in electromagnetic devices because of desirable characteristics. The magnetic characteristics of a transformer iron core will be examined in this experiment by displaying voltages v y and v x proportional to B and H, respectively, on an oscilloscope. The excitation frequency used will be 60 Hz. B is the symbol used for the flux density and H is the symbol used for magnetic field intensity (sometimes referred to as magnetizing force). A typical B-H hysteresis loop for a ferromagnetic material is shown in Fig. 1. With symmetrical excitation in the positive and negative halves of the excitation voltage, the resulting hysteresis loop will be symmetrical about the origin. The zero crossings are given special names on both the B and H axis. Fig. 1 Typical B-H hysteresis loop for a ferromagnetic material The value of B when H is zero is given by the symbol B r and the name residual (remnant) flux density. This is the value of flux density that would remain in the material if the excitation were removed from the material. The value of H when B is zero is given the symbol H c and the name coercive magnetic field intensity (historically named coercive force). This value of magnetic field intensity is the value required to coerce the flux...
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This note was uploaded on 09/29/2008 for the course EEE 360 taught by Professor Gorur during the Spring '08 term at ASU.
- Spring '08