By hvhipot 
HV Hipot Electric Co., Ltd. specializes in producing series resonance (also known as AC withstand voltage test device). Next, we will share with you the characteristics of circuit series resonance phenomenon.
Variable frequency series resonance consists of a variable frequency power supply, excitation transformer, reactor, and capacitive voltage divider. The capacitor and reactor of the test sample form a series resonant connection; The voltage divider is connected in parallel to the test sample to measure the resonant voltage on the test sample and provide an overvoltage protection signal; The frequency modulation power output is coupled to the series resonant circuit through an excitation transformer, providing excitation power for series resonance. The variable frequency series resonance test device applies the principle of series resonance, uses an excitation transformer to excite the series resonance circuit, adjusts the output frequency of the variable frequency controller, and causes the circuit inductance L and the test sample C to resonate in series. The resonance voltage is the voltage applied to the test sample. The frequency conversion resonance test device is widely used in industries such as power, metallurgy, petroleum, and chemical engineering, and is suitable for the handover and preventive testing of high-capacity, high-voltage capacitive specimens.
What are the characteristics of a circuit after series resonance occurs:
1. The current and voltage have the same phase, and the circuit is resistive.
2. The series impedance is minimized and the current is maximized: at this point, Z=R, then I=U/R.
3. The voltage at the inductor end is equal in magnitude to the voltage at the capacitor end, opposite in phase, and compensates for each other. The voltage at the resistor end is equal to the power supply voltage.
4. The ratio of the voltage at the inductor (capacitor) terminal to the power supply voltage during resonance is called the quality factor Q, which is also equal to the ratio of the inductance (or capacitance) to the resistance. When Q>>1, the voltage on the inner L and C is much higher than the power supply voltage (similar to resonance), which is called series resonance and is commonly used for amplifying signal voltage; But series resonance should be avoided in power supply and capacitance circuits