What are the conditions for generating series resonance? Wuhan UHV specializes in the production of series resonance, with a wide range of product selection and professional electrical testing. To find series resonance, choose Wuhan UHV.
The series resonance withstand voltage test is a new method of high voltage testing that uses the inductance of a reactor and the capacitance of the test object to form an LC series circuit, adjusts the voltage frequency output of the variable frequency power supply, achieves series resonance, and obtains high voltage on the test object. It has been well received by experts and has been widely used at home and abroad.
Currently, we have developed many detection instruments using the principle of series resonance, including series resonance test devices, cable variable frequency series resonance test devices, substation variable frequency series resonance test devices, and resonant boost devices for CVT inspection.
According to the principle of resonance, we know that when the inductance value X1 of the current reactor L is equal to the capacitance value Xc in the circuit, the circuit reaches resonance state. At this time, only the circuit resistance R consumes active power in the circuit, while reactive power oscillates back and forth between the reactor and the capacitor of the test sample, thereby generating high voltage on the test sample.
The condition for generating series resonance: X L=X C
Due to the high voltage generated by series resonance in L and C, it may cause damage to the breakdown of coils or capacitors. Therefore, in power engineering, series resonance should be avoided as much as possible, and it is particularly important to use series resonance testing devices to detect power systems.
Impedance condition, after resonance, the imaginary parts are equal in sign and opposite in sign. The series impedance is equal to 0, and the parallel impedance is equal to infinity. At resonance, the resonant current of the series circuit is infinite; The resonant voltage of a parallel circuit is infinite (theoretical value). In a series circuit of resistors and inductors, the phenomenon of power supply, voltage, and current being in phase occurs, which is called series resonance. Its characteristics are: the circuit is purely resistive, the power supply, voltage, and current are in phase, the reactance X is equal to 0, and the impedance Z is equal to the resistance R. At this time, the impedance of the circuit is the smallest, the current is the largest, and high voltages many times higher than the power supply voltage may be generated on the inductors and capacitors. Therefore, series resonance is also known as voltage resonance.
The resonance voltage is superimposed with the original voltage, and parallel resonance: In parallel circuits of resistors, capacitors, and inductors, the phenomenon of the circuit terminal voltage and total current being in phase is called parallel resonance. Its characteristics are that parallel resonance is a complete compensation, and the power supply does not need to provide reactive power, only the active power required by the resistor. During resonance, the total current of the circuit is minimized, and the branch current is often greater than the total current in the circuit. Therefore, parallel resonance is also called current resonance.
In a circuit where resistors, capacitors, and inductors are connected in series, the role of inductive reactance Xl and Xc is directly subtracted. If certain conditions are met, such that Xl=Xc, the reactance of the circuit is equal to zero, the current and voltage phases in the circuit are the same, and there is no reactive power exchanged between the resistor, inductor, or capacitor. This state of the circuit is called series resonance.
In an AC circuit with resistor R, inductor L, and capacitor C components, the voltage at both ends of the circuit is generally different in phase from the current in it. If we adjust the parameters or power frequency of circuit components (L or C), we can make their phases the same, and the entire circuit appears purely resistive. When a circuit reaches this state, it is called resonance.
In a series circuit composed of resistors, inductors, and capacitors, series resonance occurs when the capacitance reactance XC=inductance reactance XL is equal, and the phase of the voltage U and current I in the circuit are the same. When a series resonance occurs in a circuit, the impedance of the circuit Z=√ R2+XC-XL2=R, the total impedance in the circuit is the smallest, and the current will reach its maximum value.
In a sinusoidal AC circuit with R, L, and C components, the voltage and current at both ends of the circuit are generally different phases If the parameter values of circuit components are changed or the frequency of the power supply is adjusted, the voltage and current of the circuit can be in phase, causing the impedance of the circuit to exhibit resistance properties. A circuit in this state is called resonance. According to different connection forms of circuits, resonance phenomena can be divided into series resonance and parallel resonance. In R, L, and C series circuits, when XL=XC in the circuit, the impedance angle ∧=0, that is, the power supply voltage and current are in phase, this phenomenon is called series resonance The characteristics of series resonance: When resonance occurs, the impedance reaches its minimum value due to the inductance XL being equal to the capacitance XC, resulting in a resistive circuit.
When the voltage U remains constant, the current I in the circuit reaches its maximum value Since XL=XC during resonance, UL=UC, and UL and Uc have opposite phases, they cancel each other out when added together, so the voltage on the resistor is equal to the power supply voltage When a series circuit resonates, it has certain characteristics. Understanding the resonance phenomenon can utilize these characteristics and prevent the harm caused by certain characteristics The harmonic filtering device utilizes the characteristics of series resonance to separately filter out the main harmonics In ordinary reactive power compensation devices, series resonance should be avoided because when series resonance occurs, the voltage on the capacitor element will increase, which may cause the insulation layer of the capacitor to be broken down But in radio engineering, the selectivity of series resonance phenomenon and the obtained higher voltage can be used to extract the signal that needs to be received Report the quality factor Q in LC frequency selective resonant circuit, which is defined as Qo=WoL/r, where Wo is the resonant frequency of the circuit and r is the consumption resistance of inductance L.
