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Regarding the phenomenon of series resonance and equivalent circuit power lines
2025-09-23The resonance phenomenon of voltage and current in electrical engineering is well known. In a series circuit with inductance and capacitance, series resonance and electrical parallel resonance occur in parallel at certain resonant frequencies. In a series circuit, this phenomenon corresponds to the condition that the inductance and capacitance resistance are equal. The circuit becomes purely active.As the frequency increases, the inductance and resistance increase, while the capacitance and resistance decrease. At the resonant frequency, their values are equal and cancel each other out, and enter the variable frequency series resonant mode. A similar phenomenon occurs when the current in the power cord changes. Under certain loads (currents), series resonance modes may occur on them. This situation occurs when the capacitive power generated is equal to the inductive power consumed. The power corresponding to this condition is called 'natural'.Calculations show that at the reson
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Series resonance and parallel resonance
2025-09-23In AC circuits containing capacitors, inductors, and resistors with series resonance, forced electrical resonance of current and voltage occurs. At a certain frequency of alternating current, inductance and capacitance resistance may be equal (Xt=Xc). This means that the current intensity and applied voltage vary in the same phase, as if there were only Ohmic resistors in a circuit, and the voltage amplitudes on inductors and capacitors are the same but opposite in phase. This phenomenon is called series resonance or variable frequency resonance. The resonant frequency is determined by the formulaThe series resonance phenomenon is used in radio engineering to tune circuits to the desired frequency.When the frequency approaches the resonant frequency C0res [t] when a voltage is applied, there is a sharp decrease in the amplitude of the current intensity in an AC circuit powered by parallel connected capacitors and inductors (ignoring the active resistance due to its small size). Eco ->s
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Resistive properties of series resonance
2025-09-23The series RLC circuit consists of a resistor R, an inductor L, and a capacitor C connected in series. As in an ideal series LC circuit without resistance, oscillation with resonant frequency may occur in an RLC circuit, but due to the presence of resistance, this resonant frequency will attenuate.Series resonance (also known as variable frequency resonance) occurs at the frequency with the minimum impedance of the circuit, where the reactance of the circuit is zero. In other words, if the impedance is only resistive without reactance, i.e. its imaginary part is zero, this situation will occur. When the reactance of an inductor and a capacitor is equal, resonance occurs, and due to their opposite signs, they cancel each other out. The following vector diagram shows this situation.The calculator also calculates the Q factor of the serial RLC circuit - a parameter used for series resonant circuits and devices, as well as mechanical resonators. The higher the circuit resistance, the great
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Formula for calculating series resonant circuit
2025-09-22Series resonant (also known as variable frequency resonant) circuit is a circuit composed of inductors and capacitors connected in series.R is the equivalent ("virtual") active resistance of a circuit, representing the loss of reactive elements. Moreover, L and C themselves can be expressed as ideal without loss.Circular frequency: ω=2 πƒ. So the current in the circuit is α=È/Zn, where Zn is the total complex resistance of the circuit. As you know, for a series resonant circuit, it is defined as the sum of the resistances of all its elementsIt can be approximated that the active component of the input impedance R is independent of the frequency of the generator, although this is not entirely true in reality. Here, the skin effect factor plays a role, the proximity effect plays a role, and the quality factor depends on other effects. However, to understand how the reactance of a circuit varies with frequency, these subtle details can be ignored so far. The reactance component is a funct
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Damping resonance in series resonant circuit
2025-09-22If there is an active resistor R in a series resonant circuit, the differential equation for damping charge resonance in the resonant circuit is described by the formula:We introduce the attenuation coefficientThe formula can be rewritten asThe solution of this equation is an expressionIt can be seen that the frequency ω of damping resonance in a series resonant circuit depends on the parameters of the circuit and is described by the following formula:The logarithmic reduction of attenuation is determined by the formula, and the quality factor of the circuit is also determined by its parametersAs the damping coefficient δ increases, the period of damping resonance increases, and when itWhen it becomes infinite, that is, as the vibration increases, the period of damping resonance increases. Exercise is no longer periodic. In this case, the resonance quantity tends to zero. This process is called non periodic. Technically, this is called damping.The arrows of measuring instruments (voltm
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Formation of Electromagnetic Waves in Series Resonant Circuits
2025-09-22Series resonant (also known as series resonant voltage withstand device) circuit resonator is a circuit that includes connected inductor coils and capacitors. In such a circuit, current (and voltage) resonance can be excited. A resonant circuit is the simplest system in which free electromagnetic resonance may occur. Charge the capacitor with a capacitance of C to a voltage of U0. The energy stored in the capacitor isWhen a capacitor is connected to an inductor, current I will flow in the circuit, which will cause self induced electromotive force (EMF) in the coil, with the aim of reducing the current in the circuit. The current caused by this EMF (in the absence of inductive losses) will be equal to the discharge current of the capacitor at the initial moment, which means the resulting current will be zero. At this (initial) moment, the magnetic energy of the coil is zero. Then, the current generated in the circuit will increase, and the energy from the capacitor will enter the coil u
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Attention on site for series resonance test device
2025-09-19Attention on site for series resonance test device1、 Preparation before the experiment1. The number of test personnel should not be less than 2. Strictly follow the safety operation regulations related to high-voltage testing when using it;2. In order to ensure the safety and correctness of the test, in addition to being familiar with the product manual, it is also necessary to strictly follow the relevant national standards and regulations for the test operation;3. When the testing personnel open the packaging box, they check the equipment according to the packing list. If they find that the equipment does not match the packing list, they should immediately contact Guodian Xigao;4. The series resonance test device should be used by high-voltage testing professionals. Before use, the user manual should be carefully read and repeatedly operated and trained;5. When using the series resonance test device, the output is high voltage or high voltage, which must be reliably grounded and oper
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How to operate and maintain the series resonant device correctly?
2025-09-19In the testing and application of power systems and electronic equipment, series resonant devices are a key testing device that can provide the required resonant frequency and voltage. Proper operation and maintenance are crucial to ensure the stability and accuracy of the device. This article aims to provide a detailed guide on how to correctly operate and maintain the device to help users improve its performance and extend its service life.Preparation before operation is an essential step. Operators need to be familiar with the working principle, performance indicators, and operating procedures of the equipment. In addition, check if the device is intact and ensure that all connecting parts are securely fastened without any looseness. Before conducting experiments or tests, ensure that all safety measures are in place, including wearing appropriate protective equipment.When operating the device, the principle of gradually increasing the voltage should be followed. Adjust to a lower v
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What is series resonance? What is its principle?
2025-09-19In the field of electronics and electrical engineering, whether designing high-frequency circuits, testing semiconductor devices, or maintaining large power distribution systems, engineers often encounter a key concept - series resonance. So, what exactly is series resonance? What is its principle? Understanding this phenomenon is crucial because it can be cleverly utilized to improve the efficiency of applications such as wireless charging and fiber optic component testing. Improper handling can also cause overvoltage and overcurrent in the power system, leading to equipment damage. For professionals engaged in research and development, testing, or operations, mastering its principles and applications is an essential skill.1、 Working principle and core conditions of series resonanceTo gain a deeper understanding of series resonance, we first need to construct a classic RLC series circuit model: a resistor (R), an inductor (L), and a capacitor (C) are sequentially connected to an AC po
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The reason for the decrease in resonant frequency of series resonant circuit
2025-09-19A series resonance (also known as variable frequency resonance) circuit is composed of a series capacitor and a capacitor, with an inductive coil L and a resistor R.The ideal series resonant circuit consists only of an inductor (without its own resistance) and a capacitor (LC circuit). Then, in this system, the current in the circuit, the voltage across the capacitor, and the charge of the capacitor maintain continuous electromagnetic resonance. Let's take a look at the outline and consider the source of the vibration. Place the initially charged capacitor in the circuit we are describing.At the initial moment, all charges are concentrated on the capacitor and there is no current on the coil (Figure 1.1). Because there is no external electric field on the capacitor board, electrons from the board begin to "leave" into the circuit (the charge on the capacitor begins to decrease). In this case (due to the released electrons), the current in the circuit increases. In this case, the di
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Magnetic fluid in series resonant circuit
2025-09-19The influence of polarization voltage on the electrical properties of the magnetic fluid layer filling the inter electrode space of a planar parallel capacitor connected to a series resonant circuit. The formation, development, and self-organization of aggregates several millimeters in size have been recorded in the magnetic fluid layer, which affects its electrical and physical properties.The changes in the electrical and physical properties of magnetic fluids in the presence of structural formation in an electric field have been studied in many works. Structure formation under the influence of weak electric fields up to 400 kV/m. The average size of the formed structures was found to be no more than a few micrometers, and their appearance is related to the increase in dispersed phase concentration near the electrode and subsequent aggregation. The aggregation process was explained based on the thermodynamic concept of phase transition. As is well known, due to the strong influence of
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Resonance effects in series resonant and parallel resonant circuits
2025-09-19Series resonant circuitThe series resonant circuit is shown in the figure. When there is resonance in the circuit, the inductance reactance and capacitance reactance will completely cancel each other out, and only the resistance of the circuit will provide resistance to the current. In this circuit, the impedance is only equal to the value of R plus the DC resistance of the coil. The main characteristic of a series resonant circuit is that its impedance is minimized during resonance. When the frequency is adjusted above or below the resonant frequency, the impedance will increase.Due to the minimum impedance during resonance in a series resonant circuit, the current in the circuit rises to its peak. When this high current value is multiplied by the inductive and capacitive reactance, it will cause a very high voltage drop across the inductor and capacitor. In fact, the voltage drop between the two ends of the inductor and the capacitorUnder resonance conditions, the power supply voltag
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What is lightning impulse test? What is its function?
2025-09-19The lightning impulse voltage generator under UHV power can help many power workers conduct various power tests more conveniently.Lightning impulse test is a test used to evaluate the tolerance of electrical equipment and systems under lightning or surge conditions. Due to lightning being one of the strongest electrical phenomena in nature, its high voltage, high current, and rapidly rising electromagnetic waves can cause serious damage to electrical equipment. Therefore, conducting lightning impulse tests is crucial to ensure the safety and reliability of equipment.The basic principle of lightning impulseLightning impulse is an instantaneous high voltage phenomenon caused by lightning discharge. When lightning strikes, current flows rapidly in the air, forming strong electric and magnetic fields. This process generates voltages of up to millions of volts, instantly releasing enormous amounts of energy. When this voltage is applied to electrical equipment, it may cause insulation mater
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Why does the actual measured waveform of a lightning impulse voltage generator exhibit oscillations or overshoot?
2025-09-18The oscillation or overshoot of the waveform measured by the lightning impulse voltage generator is mainly due to the parasitic inductance and capacitance in the test circuit forming an unwanted resonant circuit.Core Reasons:1.Loop Stray Inductance (Primary Cause): Long high-voltage leads and the equipment itself have inherent inductance. The current changes extremely rapidly (very high di/dt). This inductance generates a back electromotive force (EMF), causing overshoot and subsequent oscillation.2.Stray Capacitance to Ground: The test object, voltage divider, and leads all have capacitance to ground. This forms unintentional LC resonant circuits with the loop inductance.3.Wave Reflection and Impedance Mismatch: If the high-voltage leads are too long, they act like transmission lines. If the generator's output impedance doesn't match the lead's characteristic impedance, voltage waves reflect back and forth, distorting the waveform and causing overshoot and ringing.Main Sol
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How to maintain and upkeep the impulse voltage generator
2025-09-18The impulse voltage generator is a high-voltage testing device that requires regular maintenance to ensure personal and equipment safety. Maintenance should pay attention to the following points:1. To avoid dust accumulation, the generator should be wiped regularly, especially the surface of the insulation rod should be kept clean. (Note: Do not wipe with liquids such as water or alcohol);2. After using the equipment for a period of time, lubricating oil or butter needs to be added to each mechanical transmission part. Suggest adding it once a month, depending on the actual situation;3. Ensure that the equipment has a good operating environment (condition);4. The semiconductor paint of the high-voltage rectifier transformer on the surface of the upper section porcelain sleeve near the central flange should be well protected; If wear or failure is found and strong corona occurs, semiconductor anti corona paint should be sprayed to make the corona disappear basically;5. If there is any a
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Working principle and application analysis of lightning impulse voltage generator
2025-09-18Lightning impulse voltage generator is a high-voltage testing equipment that simulates natural lightning impulse and is widely used in the insulation performance assessment of power equipment. It generates instantaneous high voltage pulses through special circuit design, providing important guarantees for the safe operation of the power system.1、 Working principle: Simulate lightning impulse waveformThe core of a lightning impulse voltage generator is to generate steep high-voltage pulses through capacitor energy storage and discharge circuits. The device first stores electrical energy in a high-voltage capacitor bank, and then releases the energy in a short period of time through a switching device, forming a surge voltage waveform with extremely fast rise time and short duration. This waveform simulates the instantaneous voltage characteristics when lightning strikes power equipment, and can truly reflect the insulation performance of the equipment under special conditions2、 Key tech
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Precautions for lightning impulse voltage generator of power transformer
2025-09-18A lightning impulse voltage generator is an experimental device that can generate high-voltage pulses that simulate natural lightning waves. It is mainly used to test whether the insulation performance of power equipment (such as transformers, lightning arresters, insulators, etc.) is reliable when struck by lightning.Precautions during the use of lightning impulse voltage generator1. All connecting wires should be as short as possible, and all grounding should be low impedance and properly connected to avoid interference.2. According to national standards and relevant technical provisions, confirm the test type and test voltage of each terminal, and determine the transformation ratio of the impulse voltage generator and voltage divider used based on the test voltage of different windings. For three-phase transformers with tap connections, lightning impulse tests are generally conducted at two limit tap connections and rated tap connections.3. The transformer assembly is intact, and qu
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Series resonance in RLC circuit
2025-09-18The basic relationship during resonanceIn the figure, a is a symbolic value model that includes series connected resistors, inductors, and capacitors. For the sake of certainty, let us assume that the complex number shown in the figure is a complex number of significant values.This type of chain is widely used in engineering practice, but it is considered separately.Series resonant circuit:A symbolic model of a chain; Vector diagram during b-resonanceDue to the series connection of components in a given circuit, only series resonance can be observed. The complex input resistance of the circuit relative to terminals "1" and "2" is equal toThe resonance condition is the equal BX of the imaginary part of zero Z, that isTherefore, during resonance, the reactance of inductance and capacitance are equal. Under the given parameters L and C, resonance occurs at frequencyThe symbol 0 for the resonant frequency ω used here will be used in the following text.The state of the chain is determined b
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Series resonant circuit
2025-09-18In a series resonant circuit, the generator is connected in series with the coil and capacitor. For example, in the case of inductive coupling, the resonant circuit is continuous because an electromotive force is induced in the coil, which is equivalent to connecting the generator in series with coil L and capacitor C. The figure shows the equivalent relationship of these transformations.During resonance, a series circuit has the following characteristics:1. The minimum loop resistance is equal to Rpot.2.The voltage across the capacitor (or coil) is Q times the voltage of the generator. Q is the quality factor of the circuit.3. The maximum and equal current flowing through the circuitThe diagram illustrates a specific example of a series resonant circuit, and Figure 9 shows its frequency characteristics, provided that the internal resistance of the generator is small.Therefore, voltage resonance occurs in a series resonant circuit. For undeveloped circuits containing series connected i
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Q factor of series resonant circuit
2025-09-18According to the definition, the quality factor of a series resonant (also known as frequency modulated series resonant) circuit is determined by the following expression:Among them, W max is the maximum energy stored in the circuit at the resonant frequency, and P is the active loss power under the same conditions.During voltage resonancesimultaneouslyTherefore, the expression for the circuit quality factor takes the following form:itReceived the name of the characteristic impedance of the circuit.According to the expression, this expression indicates that the quality factor exceeds the reactance W0L and 1/W0C is higher than the active resistance r.ConsideringAccording to the formula:From the above equation, it can be concluded that:That is to say, the quality factor of the considered circuit is determined by the ratio of the voltage across L or C at resonance to the voltage value applied to the circuit.The figure shows the frequency dependence of current for two consecutive series re
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