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What Is The Harm Of Series Resonance In The Circuit System?

Time:2020-01-15 Number:21

Series resonance devices are widely used in power systems. What is series resonance? What is the harm of series resonance in the circuit system?

What is series resonance?

In a series circuit composed of resistance, inductance, and capacitance, when the capacitive reactance XC is equal to the inductive reactance XL, that is, XC = XL, the phase of the voltage U and the current I in the circuit are the same, and the circuit is purely resistive. This phenomenon called series resonance. When the circuit has series resonance, the impedance of the circuit is Z = √R2 + (XC-XL) / 2 = R. The total impedance in the circuit is the smallest and the current will reach the maximum value. When resonance occurs, the inductance is equal to the capacitive reactance, so the inductance And the effective value of the voltage across the capacitor is equal, that is: UL = UC. And because its phase is opposite, these two voltages cancel each other. The effective voltage value of the capacitor or inductor is: UL- = UC = XLI0 = ω0LIO = ω0LU / R.

What is the harm of series resonance in the circuit system?

In the formula, ω0LU / R is called the quality factor of the resonant circuit, and it represents the voltage ratio, that is, UC / U or UL / U. The figure of merit is an important parameter for measuring the characteristics of a resonant circuit. If the reactance in the circuit is larger and the resistance is smaller, the quality factor is higher. Therefore, the voltage value on the capacitor or inductor will be much larger than the applied voltage. In general, the figure of merit of a resonant circuit of a capacitor and a capacitor can reach a few hours or even hundreds. So series resonance is also called voltage resonance. In the circuit system, series resonance will generate overvoltages that are several times higher than the rated voltage of the power grid, causing great harm to the safety of power equipment.

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