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AC withstand voltage test system
2025-06-17AC voltage tester? Wuhan UHV specializes in producing AC withstand voltage testers with a wide range of product options. When looking for an AC voltage withstand tester, choose Wuhan UHV. Today, taking the Wuhan UHV cable AC withstand voltage series resonant device as an example, we will briefly introduce the AC withstand voltage tester, a portable variable frequency resonant boost device for cables. It uses the method of adjusting the frequency of the power supply to achieve resonance between the reactor and the tested capacitor, obtaining high voltage and high current on the tested object. This is a new method and trend in current high-voltage testing, which has been widely used both domestically and internationally. The frequency conversion resonant boost device adopts a dedicated SPWM digital waveform generation chip with a frequency resolution of 16 bits, and the frequency fineness can reach 0.1Hz between 20-300Hz. It adopts an orthogonal asynchronous fixed carrier
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AC withstand voltage test method for transformers
2025-06-17What is the AC withstand voltage test method for transformers? Wuhan UHV specializes in producing AC voltage withstand testers with a wide range of product options. When looking for an AC voltage withstand tester, choose Wuhan UHV. AC withstand voltage test is an external AC test voltage applied to the insulation of electrical equipment. The test voltage is higher than the rated working voltage of the equipment and lasts for a certain period of time (usually 1 minute). AC withstand voltage test is a test that best meets the actual operating conditions of electrical equipment and is an important means to avoid insulation accidents. Therefore, the AC withstand voltage test is a decisive test among various insulation tests.Wiring principle for AC withstand voltage testThe wiring for the AC withstand voltage test should be determined according to the requirements of the test object (voltage, capacity) and the existing test equipment conditions. Usually, high-voltage complete sets o
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AC withstand voltage testing
2025-06-16AC withstand voltage test? Wuhan UHV specializes in producing AC voltage withstand testers with a wide range of product options. When looking for an AC voltage withstand tester, choose Wuhan UHV.The AC withstand voltage plays a decisive role in assessing the main insulation strength of transformers and checking for local defects in the main insulation. It is an important means of checking and verifying the quality of transformer design, manufacturing, and installation.Scope of AC withstand voltage test1. For transformers with a capacity of 8000KV or less and a rated winding voltage of 110KV or less, an AC withstand voltage test should be conducted for the terminal test.2. Transformers with a capacity of 8000KV. A or above and a rated winding voltage of 110KV or below can undergo terminal AC withstand voltage testing when equipped with testing equipment.3. For transformers with a rated winding voltage of 110KV or above, the neutral point should undergo an AC withstand voltage test, and
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AC voltage withstand test device
2025-06-13Communication voltage withstand test device? Wuhan UHV specializes in producing AC voltage withstand testers with a wide range of product options. When looking for an AC voltage withstand tester, choose Wuhan UHV. During the operation of power equipment, insulation will gradually deteriorate due to the long-term effects of electric fields, temperature, and mechanical vibrations, including overall deterioration and partial deterioration, forming defects. AC withstand voltage test is the most effective and direct method for evaluating the insulation strength of power equipment, and is an important part of preventive testing. In addition, due to the fact that the AC withstand voltage test voltage is generally higher than the operating voltage, the equipment has a large safety margin after passing the test. Therefore, AC withstand voltage test is an important means to ensure the safe operation of power equipment.The Wuhan UHV series variable frequency automatic resonance test devic
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Preventive measures for using insulation oil dielectric loss tester
2025-06-12Wuhan UHV professional production insulation oil dielectric loss tester 1. The instrument must be grounded, otherwise it will alarm. Do not enter the main menu. 2. Remove the oil cup from the instrument and ensure that the power is turned off. 3. After installing the oil cup, check the empty cup first. The capacitance value should be 60 ± 2pF, and the dielectric loss should be less than 0.005%; If the capacitance value is greater than 62, it should be reinstalled, the dielectric loss is invalid, and the oil cup should be cleaned again. 4. The new oil cup may have dust or cloth dust, so after installing the new oil cup, clean it three times with sample oil (add oil, rotate around the inner ring up and down, and then drain the water). The cleaning and heating effect is better. 5. When installing porcelain, pay attention to moderate force and do not apply too much force to avoid damaging the porcelain or causing the capacitance value to be unqualified after installation. 6. The temperatur
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RLC series resonant circuit experiment
2025-06-11Series resonance? Wuhan UHV specializes in producing series resonance. When looking for series resonance, choose Wuhan UHV. Starting from the equation analysis of the RLC series resonant circuit, the Wuhan UHV circuit experiment derived the resonant frequency, quality factor, and input impedance of the circuit in the resonant state. Based on Multisim simulation software, the RLC series resonant circuit was created, and its theoretical basis was verified using virtual instruments and simulation analysis methods, respectively. The results indicate the consistency between simulation and theoretical analysis, providing a feasible research method for the application of simulation analysis in electronic circuit design. The resonance phenomenon is a specific working state of a sinusoidal steady-state circuit. Usually, resonant circuits are composed of capacitors, inductors, and resistors, and can be divided into series resonant circuits, parallel resonant circuits, and coupled resonant circ
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Power cable fault tester
2025-06-10Power cable fault tester? Wuhan UHV specializes in producing power cable fault testers with a wide range of product options. When looking for a power cable fault tester, choose Wuhan UHV. At present, there are various types of power cable fault testers on the market, with prices ranging from several thousand yuan to several hundred thousand yuan, making it difficult for users to choose when purchasing such instruments. The materials, structures, uses, laying methods, voltage levels, and wiring methods of cables used in various industries are not the same. The common fault characteristics and solutions should also be different. At present, there are uneven manufacturers in the market, and few products can effectively solve various cable faults. The power cable fault tester developed by Wuhan UHV precisely solves various cable fault problems. Let's introduce them in detail below. Working principle of power cable fault testerThe working principle of the power cable fault tester is t
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How to estimate the series resonant frequency?
2025-06-06A series resonant capacitor is simply the result of surface mount devices and pin leads. For a typical plug-in capacitor, its average equivalent series inductance is 2.5nH/2.54mm. The average equivalent series inductance of surface mounted capacitors is 1nH. Based on the above, it is important to consider the equivalent series inductance of capacitors when using decoupling capacitors. Surface mounted capacitors have better performance than plug-in capacitors at high frequencies because their equivalent series inductance is very low. Blocking network 2 is used to block f1=747KHZ, taking C2=1250pF, then:What is resonant frequencyA power of 1mW is applied on a 600 Ω load, and the voltage value on the load is at zero level. At this time, the AC voltage on the load is 0.775V.Definition of resonant frequencyThe impedance of an ideal capacitor decreases with increasing frequency, while the impedance of an actual capacitor exhibits capacitive characteristics at lower frequencies, where the im
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The function of AC series resonant reactor
2025-06-04As the name suggests, a reactor refers to a series connected inductor in a circuit. In the field of reactive power compensation and harmonic control, series reactors mainly refer to reactors connected in series with capacitors. The series connected reactor and capacitor form a resonant circuit. To eliminate or filter harmonics. Reduce the surge current multiplier and surge frequency of the capacitor bank, protect the capacitors, and facilitate the selection of supporting equipment. Form a complete resonant circuit together with the capacitor bank to filter out specific subharmonics. After the inductance of the series filter reactor and the capacitance of the capacitor are fully adjusted, an AC filter with characteristic subharmonics is formed to filter out the characteristic subharmonics, thereby reducing the voltage distortion of the harmonic on the bus and reducing the line. Harmonic current improves the power quality of the network and bus power supply. A bias that forms a resona
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The use and precautions of non partial discharge withstand voltage test device
2025-05-30In order to work in different usage environments and conditions, while adapting to different voltage levels and capacity requirements. Our company has designed a series of power frequency non partial discharge test transformers and their corresponding complete sets of equipment, including four models and over sixty specifications. Power frequency non partial discharge test transformers are divided into four types according to their structural types: single-phase iron shell type, single-phase iron shell cascade type, single-phase insulation cylinder shell type, and single-phase insulation cylinder external cascade type. Single phase iron shell is suitable for gas applications with low voltage capacity, easy portability, or high voltage capacity but low partial discharge requirements; Suitable for situations where the voltage is not too high and the use is relatively fixed. Users can choose single-phase insulated cylinder cascade products according to different needs. They are suitable
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What is the difference between the partial discharge high-voltage test system and the partial discharge test device?
2025-05-29What is the difference between high-voltage non partial discharge withstand voltage test kit and partial discharge withstand voltage test kit? This equipment is capable of conducting power frequency withstand voltage tests and partial discharge tests on power transformers, high-voltage circuit breakers, power cables, transformers, and insulation materials of 35kV and below, and belongs to the non partial discharge withstand voltage test equipment group. 1. Characteristics of the product. This device is fully functional, compact in size, lightweight, aesthetically pleasing, and easy to move. 2. All operations can be completed through the keyboard, all measurement and control data are digitized, and the entire workflow is intelligent.3. There are four display windows at the same time, which can display high and low voltage, current, and withstand voltage time. There are also multiple status indicator lights that make the workflow and status clear at a glance. 4. Enter automatic or ma
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The influence of operating parameters on the error of electric energy meters
2025-05-28The electric energy meters calibrated from the calibration room are all measured under normal conditions specified in the regulations. In fact, it is impossible for all electric energy meters to operate under the rated conditions specified in the regulations. Operating parameters such as voltage, load, waveform, etc. are subject to variation, which can cause additional errors in the energy meter. The reasons for the formation of additional errors in electric energy meters and their compensation measures will be discussed below. 1. The impact of voltage changes on errorsDue to the voltage variation of the power grid usually between 90% and 105% Ue, there is a voltage drop in each line, which causes the voltage U applied to the energy meter to be different from the rated voltage Ue. This will cause the voltage working flux to not change proportionally with the voltage, and destroy the original proportional relationship between the voltage suppression torque, compensation torque, and dri
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Analysis of Grounding Line Selection and Criteria for Small Current Grounding Systems
2025-05-271. IntroductionIn China's 35kV and 10kV power systems, the neutral point of transformers is often non directly grounded (for small grounding current systems). When a single-phase grounding fault occurs in the line, the value of the fault current is often much smaller than the load current. The fault phase voltage drops to zero, and the non fault phase voltage rises to times the phase voltage. However, the line voltage between the three phases still remains symmetrical and has no impact on the power supply load. Therefore, the regulations allow for continuous operation for 1-2 hours. However, in actual operation, accidents such as power cable explosions, TV fuse melting or even burning, and bus short circuits may occur due to overvoltage. Therefore, quickly determining the system grounding point and eliminating single-phase grounding faults is of great significance for the safe operation of the system. The traditional method of finding grounding fault lines is to sequentially discon
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Classification and protection of oil immersed transformers
2025-05-26According to the number of phases of a single transformer, it can be divided into three-phase transformers and single-phase transformers. In three-phase power systems, three-phase transformers are generally used. When the capacity is too large and limited by transportation conditions, three single-phase transformers can also be used to form a transformer group in three-phase power systems. According to the number of windings, it can be divided into double winding transformers and three winding transformers. Typical transformers are double winding transformers, which have two windings on the iron core, one as the primary winding and one as the secondary winding. A three winding transformer is a transformer with a larger capacity (above 5600 kVA) used to connect three different voltage transmission lines. In special cases, there are also transformers that use more windings. According to the structural form, it can be classified into iron core transformers and iron shell transformers. I
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Advantages of series resonant power supply in power system applications
2025-05-221. The required power capacity is greatly reduced. Series resonant power supply generates high voltage and high current through resonance between resonant reactor and tested capacitor. In the entire system, the power supply only needs to provide the active consumption part of the system. Therefore, the required power supply for the test is only 1/Q of the test capacity2. The weight and volume of the equipment have been greatly reduced. In a series resonant power supply, not only is the bulky high-power voltage regulating device and ordinary high-power power frequency test transformer eliminated, but the resonant excitation power supply only requires 1/Q of the test capacity, greatly reducing the weight and volume of the system, usually 1/3-1/5 of ordinary test devices 3. Improve the waveform of the output voltage. A resonant power supply is a resonant filtering circuit that can improve the waveform distortion of the output voltage, obtain a good sine waveform, and effectively prevent
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Research on anti-interference methods for digital time relays
2025-05-21Abstract: Through the analysis of the causes of misoperation of digital time relays under electromagnetic interference conditions, this paper preliminarily discusses the anti-interference measures of digital time relays under such interference conditions, and provides reference for further improving the anti-interference performance and reliability of digital time relays. Keywords: Digital time relay, anti-interference filteringIntroductionWith the continuous development of digital technology and related professions, relay protection technology has also made great progress, such as the application of static relays in power systems. Among them, digital time relays, as basic components, have been widely used in various relay protection and automatic control circuits, enabling the controlled equipment or circuit to obtain the required delay and achieve selective coordination between main protection and backup protection. Digital time relays are used for relay protection, primarily to repl
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The advantages of conducting AC withstand voltage tests on cables
2025-05-20With the development of the national economy and the improvement of the voltage level of urban power supply, cross-linked polyethylene insulated power cables (XLPE) have been increasingly widely used at home and abroad due to their reasonable process and structure, excellent electrical performance, and safe and reliable operating characteristics. Especially in the field of high-voltage transmission, significant progress has been made. Compared with oil filled cables, cross-linked cables are easy to lay and install, have simple operation and maintenance, and do not have oil leakage problems. However, recent operations and research have shown that the insulation of cross-linked polyethylene cables is prone to dendritic discharge during operation, causing insulation aging and damage, seriously affecting the service life of cross-linked polyethylene insulated power cables. Therefore, fully understanding the insulation characteristics of cross-linked cables, timely and effectively discoveri
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Why use high current to measure the circuit resistance of a circuit breaker?
2025-05-16Many high current electrical equipment in the power system require accurate measurement of circuit resistance values during preventive and handover tests. Circuit breakers are important electrical equipment in power systems. The national standards GB763 and GB50150, as well as the power industry standard DL/T596, stipulate that the measurement of the conductive circuit resistance of circuit breakers should be carried out using the DC voltage drop method, with a current not less than 100A.The resistance of the conductive circuit of a circuit breaker mainly depends on the contact resistance between the moving and stationary contacts of the circuit breaker. The existence of contact resistance increases the loss of the conductor when it is energized, causing the temperature at the contact to rise. The magnitude of its value directly affects the current carrying capacity during normal operation and to some extent affects the ability to cut off short-circuit current. Therefore, the resistanc
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Method for measuring transformer resistance exceeding the standard using a DC resistance tester
2025-05-14The DC resistance tester under UHV power can help many power workers conduct various power tests more conveniently.The measurement of DC resistance is to check the welding quality of the winding and the short-circuit situation between the windings; Whether the position of the tap changer is good and whether the actual position is consistent with the indication; Whether the wire is broken or loose; And the winding of the strands did not break. Stocks and so on. The measurement of DC resistance is an essential inspection item for transformers after major repairs, pre tests, and changes in tap changer positions. It is also an important inspection item after faults.In general, measuring the DC winding of transformer windings and high-power inductive devices using conventional methods (bridge method and voltage drop method) is a time-consuming and labor-intensive task. In order to change this situation, shorten measurement time, and reduce the workload of testers, Wuhan Hezhong Electric has
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The usage steps and diagnosis of cable fault testing
2025-05-14The cable fault tester under UHV power can help many power workers conduct various power tests more conveniently.1. Fault diagnosis:The nature of cable faults can be simply divided into the following categories:1) Breakage: One or more core wires of a cable are disconnected, causing a signal interruption. This type of fault is detected using the pulse method.2) Mixed wire: There are three types: grounding, self mixing, and other mixed wires, which refer to insulation layer damage between core wires and leads, between the same pair of core wires, and between core wires. The insulation resistance of different pairs of wires drops to a very low level (several hundred to several thousand ohms), and even short circuits, seriously affecting signal quality. This type of fault can be tested using the pulse method first, and when the waveform of the cable fault tester is difficult to recognize, the bridge method can be used for side measurement.3) Poor insulation: The insulation material of the
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