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Unformatted text preview: Electromagnetic Interference (EMI) and Line Power Quality Problems Diodes and thyristor converters, essentially constitute a nonlinear load on electric utility systems, and this type of load has grown enormously in recent years. The line waveforms generated by these converters are far from sinusoidal, and as a result, serious EMI (electromagnetic interference) and harmonic problems are created. EMI Problems EMI problems arise due to the sudden changes in voltage ( dv/dt ) or current ( di/dt ) levels in a waveform. In fact, any fast switching power semiconductor device creates high dv/dt and di/dt in the waveforms. A conductor carrying a high dv/dt wave acts like an antenna, and the radiated highfrequency wave may couple to a sensitive signal circuit and appears as noise (radiated EMI). Or, a parasitic coupling capacitor may carry this noise signal through the ground wire (conduct EMI). Similarly, a high di/dt current wave may create conducted EMI by coupling through a parasitic mutual inductance. The EMI problems create may create conducted EMI by coupling through a parasitic mutual inductance....
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This note was uploaded on 10/05/2011 for the course EECS 101 taught by Professor Hero during the Spring '11 term at National Taipei University.
 Spring '11
 Hero
 Electromagnet

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