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Analysis of the Voltage Withstand Test Principle of Variable Frequency Series Resonance
2025-09-30Analysis of the Voltage Withstand Test Principle of Variable Frequency Series ResonanceThis article mainly introduces the voltage withstand test principle of series resonant frequency conversion Firstly, the following components were introduced:The series resonant frequency detection kit mainly consists of a frequency controller, excitation transformer, reactor, and high-voltage divider. The technology of variable frequency system controllers can be divided into two categories: desktop control environment for 20KW and above, and portable box type for 20KW and below; It can be composed of a controller and a filter.The main function of a frequency controller is to have a fixed amplitude and adjustable amplitude and frequency sine wave with a frequency of 380V or 200V sine alternating current. And provide a power source for the development of the entire equipment. The function of the excitation transformer is to increase the output voltage of the variable frequency power supply to the app
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Working principle of voltage withstand test for variable frequency series resonance
2025-09-30Analysis of the working principle of voltage withstand test for frequency conversion series resonanceIn today's series resonant frequency voltage test, we first introduce the principle of the composite:The complete set of equipment for a resonant structure test system using frequency conversion technology is mainly composed of a frequency converter controller, excitation transformer, high-voltage reactor, high-voltage voltage divider, etc. Variable frequency controllers are divided into two categories: desktop controllers with 20KW and above, and portable box type controllers with 20KW and below; composed of controllers and filters .The main function of a frequency controller is to have a fixed amplitude and adjustable amplitude and frequency sine wave with a frequency of 380V or 200V sine alternating current. And provide a power source for the development of the entire equipment. The exciter frequency power transformer is used to increase the output voltage to a suitable test volt
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Many advantages of variable frequency series resonance test device
2025-09-30The frequency conversion series resonance test device integrates voltage regulation, frequency regulation, control, and protection functionsThe variable frequency series resonance test device mainly consists of a variable frequency controller, excitation transformer (air pressure variable), high-voltage reactor, high-voltage voltage divider, etc. Variable frequency controllers are mainly divided into two categories: desktop controllers with 20KW and above, and portable box controllers with 20KW and below; Composed of a controller and a filter (filter) The main function of the series resonant frequency of the variable frequency controller of the testing device is to convert a fixed frequency AC current with amplitude and frequency (frequency) of 380V or 200V into a sine wave with adjustable amplitude and frequency. And provide power supply for the entire frequency conversion series resonance test device. The function of the excitation transformer is to raise the output voltage of the va
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Test wiring and operation steps of frequency conversion series resonance test device
2025-09-29The set voltage, frequency modulation control (control), and protection functions of the (frequency conversion) series resonance testing equipment (also known as variable frequency series resonance) are integrated as a whole, eliminating the need for bulky regulators and providing easy operation and intuitive readings. Due to the high Q value of the information system (30-120), the constraints on on-site testing caused by the insufficient capacity of the working power supply market have been effectively addressed.Test wiring and procedure for frequency conversion series resonance test deviceProcedure for experimental operation1. Follow various test wiring methods to ensure good contact at each point, ensure that one point is grounded and located closest to the voltage divider .2. Ensure that the power connection is correct.3. Turning on the power control switch of the host system will display the main menu4. Move the cursor to: Test parameter settings; Press the confirm button.
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Introduction to the Function of Frequency Conversion Series Resonance Test Device
2025-09-29Series resonance, also known as variable frequency series resonance test device, is mainly designed and manufactured for AC withstand voltage testing of primary electrical equipment in substations of 220KV and below. The variable frequency series resonance test device can meet the AC withstand voltage test requirements of capacitive equipment such as transformers, GIS systems, SF6 switches, cables, and bushings according to regulations. The frequency conversion series resonance test device can meet the requirements of both high voltage and low current (current) equipment test conditions, as well as low voltage and high current equipment test conditions The frequency conversion series resonance test device has a wide range of applications .The series resonant inverter device for frequency conversion is controlled by power, including excitation transformer (transformer), reactor, and capacitive voltage divider. One of the frequency conversion technology control system power supplies can
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Series resonance test device adjusts the output voltage of the variable frequency controller
2025-09-29Series resonance (also known as variable frequency series resonance test device) regulates the output voltage of the variable frequency controllerThe variable frequency series resonance test device applies the principle of series parallel resonance. By adjusting the output frequency of the variable frequency controller, the inductance L of the reactor in the circuit and the capacitance C of the test sample resonate, and the resonant voltage is the voltage applied to the test sample. Through the development of a system frequency controller, a power supply is provided. The voltage is initially boosted by an excitation transformer (pressure controlled variable) and applied to the reactor L and the test sample CX. By continuously changing the output frequency of the traditional frequency controller to different frequencies, the circuit is in a series resonant network state; The resonant frequency of the circuit mainly depends on the capacitance CX of the test sample and the inductance L of
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Explanation of Test Conditions for the Complete Set of Frequency Conversion Series Resonance Test Equipment
2025-09-28The test kit for series resonance frequency is based on the principle of series resonance. The excitation transformer of the series resonance output circuit is used to excite the frequency, and the controller adjusts the series resonance frequency of the test circuit inductance L and C. The resonance voltage is the voltage applied to the test. It is widely used in industries such as power, metallurgy, petroleum, and chemical, and is suitable for handover and preventive testing of large capacity and high voltage capacitance tests.The series resonance frequency testing kit can be referred to as the testing equipment for series resonance, which can be divided into modulation and style frequency modulation. A series resonant connection is generally composed of a variable frequency power supply, excitation transformer, reactor, and capacitive voltage divider to form a test reactor and capacitor; The parallel connection of the voltage divider is used to measure the resonance voltage on the s
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Application of Series Resonance Test Device
2025-09-28AC voltage withstand test is a very important test in high-voltage equipment testing, and selecting suitable testing equipment is of utmost importance for conducting AC voltage withstand test. Currently, there are two main types of AC voltage withstand test equipment: high-voltage test transformers and variable frequency series resonance test devices.High voltage test transformerHigh voltage test transformers are generally divided into two series: 1. High voltage side current of 1~2A. 2. High voltage side current of 0.1~0.2A. During the test, the appropriate test transformer is selected according to the requirements of voltage, current, frequency, and capacity. The calculation method is as follows:The main disadvantage of this method is that the experimental voltage is relatively low. In order to solve the disadvantage of low test voltage, a series test transformer can be used to increase the test voltage, but the utilization rate decreases. For example, if two test transformers are co
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Several points to note when conducting AC withstand voltage test on frequency conversion series resonance test device
2025-09-28The method of conducting AC withstand voltage test with variable frequency series resonance test device is to change the inductance and frequency in the test circuit to make the circuit in resonance state. This method can meet the test requirements of high voltage and high current. When using the variable frequency series resonance test device for AC withstand voltage test, the following points should be noted:(1) Before the experiment, it is necessary to understand whether the non-destructive testing items of the tested equipment are qualified. If there are defects or abnormalities, the test should be conducted after cleaning.(2) Adjust the gap between the protective balls to a discharge voltage of 105% to 110% of the test voltage. Test three times in a row, there should be no significant difference, and check the reliability of the overcurrent protection device operation.(3) In the experiment, if it is found that the pointer of the voltmeter swings greatly and the test substance make
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Series resonance compensation
2025-09-26Series resonance (also known as variable frequency resonance) compensation - a capacitor connected in series with the line can control the effective reactance between the two ends of the line. The effective reactance is given by the following equationIt is obvious that capacitors will reduce the effective line reactance. This leads to improvements in system performance as follows.(i) The voltage drop in the circuit is reduced (compensated), that is, the terminal voltage change is minimized.(ii) Prevent voltage collapse.(iii) Steady state power transmission increases; It is inversely proportional to X'l.(iv) Due to the increase in transient stability limit.The advantages and problems of series capacitor compensators are related. Capacitor reactance X c forms a series resonant circuit with the total series reactanceThe oscillation natural frequency of this circuit isF=system frequencyFor this level of compensationThis is subharmonic oscillation.Although series resonant compensation i
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Frequency of series resonance
2025-09-26What is resonance? When the reactance of an inductor balances the reactance of a capacitor at a given frequency, resonance occurs. In this series resonant circuit (also known as series variable frequency resonant), the current will be maximum and the impedance will be minimum. In a parallel resonant circuit, the situation is exactly the opposite.Resonance formulaThe formula for resonance is:2 * pi * f * L = 1 /（2 * pi * f * C）Among them: 2 * pi=6.2832; F=frequency, measured in Hertz, L=inductance, measured in Henry, C=capacitance, measured in FaradsWe will continue:f = 1 / [2 * pi（sqrt LC）]Among them: 2 * pi=6.2832; F=frequency, measured in Hertz, L=inductance, measured in Henry, C=capacitance, measured in FaradsA particularly simple radio frequency formula (please make sure you understand it) is:LC = 25330.3 / f 2Among them: f=frequency, measured in megahertz (Mhz), L=inductance, measured in microhenries (uH), C=capacitance, measured in picofarads (pF)By using simple algebra, we can d
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Series resonance in power systems
2025-09-26When the series combination of the inductance of the facility transformer and the parallel capacitor group in the facility resonates at the harmonic frequency injected from the distribution system, series resonance occurs. In this case, the facility itself may not be an important harmonic current generator, but due to the series LC combination "absorbing" important harmonic currents from the upstream distribution system, the equipment may still encounter resonant harmonic effects. Here is an example of a system that may experience series resonance.The voltage across the capacitor is amplified and distorted, which can be expressed as:Among them, Vh is the harmonic voltage present in the system. R is the inherent series resistance of the circuit above, not shown in the diagram. Note that the resonance values of Xt and Xc are equal and opposite in magnitude, thus canceling each other out.Application of Series and Parallel Resonance in Actual Power SystemsIn fact, due to the circuit topolo
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Introduction to series resonant circuit
2025-09-25The following figure shows a typical series resonance (also known as variable frequency resonance) circuit.In many cases, R represents the loss resistance of an inductor, and in the case of a hollow coil, it simply represents the resistance of the winding. The resistance related to capacitors can usually be ignored.The impedance of capacitors and inductors is fictitious and has opposite signs. Typically, for w0 L=1/w0C, the total imaginary part is 0, so the total impedance is R and w is 0 times. This frequency is the series resonant frequency.The general impedance characteristics of this circuit are shown in the following figure.When w0 L=1/w0, each frequency of series resonance: or frequency in Hz: F0This is the so-called Thompson formula.If R is smaller than X, then the reactance near the resonance frequency of L and X C is the series resonance frequency, and we say that the circuit has good selectivity.The selectivity of the quality factor Q is equal to the angular frequency We of e
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Q factor and bandwidth of series resonant circuit
2025-09-25The quality factor (Q) of a resonant circuit characterizes its quality. The higher value of this indicator corresponds to a narrower bandwidth (which is ideal for many circuits). Simply put, the quality factor is the ratio of the energy accumulated in the circuit reactance to the energy consumed by the active resistance of the circuit:If the resistor is connected in series with the inductor, this formula applies to both series resonant circuits and parallel resonant circuits. In fact, in practical circuits, we often worry about the resistance of inductors, which can limit the quality factor. Note: Some textbooks on parallel resonant circuits in the "Q" formula interchange X and R. This is correct for large R values connected in parallel with C and L, and our formula is correct for small R values connected in series with L.The practical application of Q factor (Q) is that the voltage across L or C in a series resonant circuit is Q times the total applied voltage, and in a parallel reson
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Forced oscillation in series resonant circuit
2025-09-25From the process of electrical engineering, it can be known that in a series resonant circuit containing inductance L, capacitance C, and active resistance R, voltage resonance occurs when the reactance is equal (X L=X C). When the frequency is e, resonance in the series circuit can be obtained. D is consistent with the frequency of free oscillation in the circuit.Normally, the current in a circuit is determined by rotationResonance (XL=XC)Therefore, in resonance, when ƒ=ƒ 0, a series circuit has a minimum resistance equal to the circuit and an active resistance of e.The quality factor of a series resonant circuit indicates how many times the voltage on its components increases during resonance compared to the e applied to the circuit. The frequency dependence of current in a series circuit is called the resonance curve of the circuit.The analytical expression for the road resonance curve isI am the current in the circuit; ƒ is the frequency of the applied e. ƒ 0=Δ ƒ - The detuning of
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What are the core safety regulations for operating a VLF Hipot Tester?
2025-09-24The VLF Hipot Tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.1. Pre-Test Preparation (The Foundation of Safety)Personnel: Operation requires two or more people. One operates, the other acts as a dedicated supervisor. The operator must be certified and familiar with the procedures.Site Isolation: Establish a clearly marked safety perimeter using barriers or warning tape, with "Danger, High Voltage" signs to prevent unauthorized entry.Reliable Grounding: The generator chassis and ground terminal must be securely connected to a qualified ground electrode using a dedicated grounding cable. This is the most critical safety measure.Status Check: Ensure the equipment under test (EUT) is completely de-energized and isolated from other equipment. Verify all test connections are correct and secure, and that the equipment's voltage regulator is at zero.2. During the Test (The Focus of Risk)Verbal Confirmation: Before any key action (e.g., "app
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Power of series resonance
2025-09-24In a circuit where resistor A, inductor I, and capacitor C are connected in series, a phenomenon called series resonance may occur. When an inductor is connected in series with active resistor A and capacitor, resonance phenomenon will be observed.When there is series resonance in a circuit, the current and voltage are in phase, that is, the angleObviously, if the conditions for series resonance occur, this equality will occurThe reactance (X, X s) of the circuit is zero.The frequencies of b, C, and the applied sine voltage represent X b and X c, respectivelyTherefore, at=X c, series resonance occurs in the circuit because the resonant frequency is equal to the frequency of the voltage supplied to the circuit.According to Ohm's Law, the current in a circuit is:The analysis of this dependency shows that the current in the circuit during resonance (X b - X c=0) is equal to the voltage divided by the active resistance:The current in the circuit reaches its maximum value because impeda
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Inductance and capacitance of series resonant circuit
2025-09-24In a series circuit with R, L, and C, the applied voltage U is equal to the sum of the voltage drops across the resistor, inductor, and capacitor. We can find itSpecify the impedance of the circuit through the following methods:We can write Ohm's law for this circuit:In the considered circuit, when the load is an active inductor and an active capacitor.So what is the current in the circuitThat is, in this case, the circuit has the smallest possible resistance, as if it only contains active resistors. In this case, the voltages on the phase of the inductor and capacitor completely cancel each other out. The voltage applied to the circuit is equal to the voltage across the active resistor, and the current is in phase with the voltage. This situation is called series resonance (also known as variable frequency series resonance).Therefore, the condition for series resonance is that the inductance, capacitance, and resistance of the circuit are equal:The phenomenon of series resonance i
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Resonance frequency of series resonance
2025-09-24Voltage resonance phenomenon is observed in a series resonant circuit composed of capacitors, inductors, and resistors. In order to ensure the energy supply of the resonant circuit, the series circuit also includes an electromotive force source E, which generates an alternating voltage with a frequency of W. During resonance, the circulating current in the series circuit must be in phase with the electromotive force. If only the total resistance of circuit Z=R+J (WL-1/W C) is activated, it ensures effective Z=R. Equality:（L-1 /WС）= 0（1）It is the mathematical condition for resonance in a resonant circuit. In this case, the current in the circuit will be I=E/R. If we transform equation (1), we obtain:WL = 1 /WС。In this expression, W is the resonant frequency of the circuit.Importantly, during the resonance process, the voltage across the inductor is equal to the voltage across the capacitor, and is:UL = U = WL * I = WLE / R The total amount of energy in inductance and capacitance (magnet
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Precautions for the Use and Maintenance of VLF hipot tester
2025-09-23The VLF hipot tester is integrated with modern digital frequency conversion technology, using microcomputer control to boost, buck, measure, protect, automate, and can be manually intervened during the automatic boost process. Due to its full electronicization, this instrument is small in size and light in weight, with a large screen LCD display that is clear and intuitive. It can also display output waveforms and print test reports.1. Before using the instrument, first observe whether the appearance of the instrument is damaged. After powering on, check if the instrument head displays properly and if the display is complete. For instruments that have not been used for a long time, check if the output terminal is corroded or aged. Otherwise, they should be cleaned up in a timely manner before use. Please refer to the "Usage Operation" method when using.2. The VLF hipot tester is a precision electronic instrument that cannot be opened arbitrarily. When opening it, we must take relevant
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