WEBVTT

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I will increase the frequency in the RL network, resistance (intensity) and coil!

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The red amplitude in advance increases with frequency (inductance: L * 2 * pi * f)

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We arrive at the phenomenon of internal resonance, observe please

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Intensity (resistance voltage: blue) is lagging and lower than the coil voltage: red

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Here we are in phase and intensity I has become zero! Internal resonance!

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If I increase the frequency again, the blue re-increases but especially 'passes before'

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The coil now behaves like a capacitor!

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The impedance of the coil now decreases proportionally to the frequency!

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How does the coil become a capacitor?

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Deepened in EMC, the explanation: a coil consists of contiguous isolated turns

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2 conductors (turns) separated by an insulator (varnish of turns) form a capacitor

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At resonance, the capacitor between turns is preponderant to the inductance of the turns

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This is why, in CEM, the theoretical formulas serve you without this practical knowledge

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This is important, and we will see it with the capacitor!

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Do not hesitate to see our EMC courses if you like it!