The series resonanceunder UHV power can help many power workers conduct various power tests more conveniently.

Inductance and capacitance are still two separate components during resonance, otherwise energy exchange cannot occur; But from the perspective of equivalent impedance, it has become a component: a resistor with a value of zero or infinity. In a series circuit composed of resistors, inductors, and capacitors, when the capacitive reactance XC is equal to the inductive reactance XL, i.e. XC=XL, the phase of the voltage U and current I in the circuit are the same, and the circuit exhibits pure resistive behavior. This phenomenon is called series resonance (also known as voltage resonance). When a series resonance occurs in the circuit, the impedance of the circuit Z=√ R2+XC-XL2=R, the total impedance in the circuit is minimized, and the current will reach its maximum value.

For ideal L and C components, when series resonance occurs, the voltage on the L and C components is equal in magnitude and opposite in direction, resulting in a total voltage of 0 (resonant impedance is zero). When parallel resonance occurs, the current in the L and C components is equal in magnitude and opposite in direction, resulting in a total current of 0 (resonant impedance is infinite). Therefore, series resonance is voltage resonance, while parallel resonance is current resonance.

Whether in series or parallel resonance, complete energy exchange is achieved between L and C during resonance, that is, the released magnetic energy is completely converted into electric field energy and stored in the capacitor; At another moment, the capacitor discharges and converts it into magnetic energy, which is stored by the inductor.

In a series resonant circuit, due to the same current flowing through series - L and C, energy exchange occurs through changes in voltage polarity; In a parallel circuit, the two ends of L and C have the same voltage, so the conversion of energy is manifested as two components with opposite current phases.

Because the series resonant circuit exhibits resistance to the external circuit because the inductive and capacitive reactance in the circuit are equal and cancel each other out, the impedance of the circuit is minimized during resonance, resulting in the maximum loop current. When the loop current is at its maximum, the voltage on the inductor and the voltage on the capacitor are both equal to the product of the loop current and their reactance, so their values may be much higher than the applied voltage. The voltage of series resonance will be much higher than the circuit voltage, and the current of parallel resonance will be very large.