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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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Comparison of advantages between clamp type grounding resistance tester and traditional grounding resistance tester
2025-05-13The clamp type grounding resistance tester under UHV power can help many power workers conduct various power tests more conveniently.Clamp type grounding resistance tester, also known as clamp type grounding resistance tester or grounding resistance tester. Widely used for measuring grounding resistance of electrical equipment in power, telecommunications, meteorology, oil fields, buildings, and industry. The clamp type grounding resistance meter does not require disconnecting the grounding wire and auxiliary electrode when measuring a grounding system with a circuit, making it safe, fast, and easy to use. The clamp type grounding resistance meter can measure grounding faults that cannot be measured by traditional methods, and can be applied in situations where traditional methods cannot measure them, because the clamp type grounding resistance meter measures the combined value of grounding body resistance and grounding body resistance. The resistance of the ground wire. The clamp type
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Testing method of commonly used transformer DC resistance rapid tester
2025-05-13The DC resistance tester under UHV power can help many power workers conduct various power tests more conveniently.1. The accuracy level of a general transformer DC resistance tester should be (0.2): the output current of transformers below 120MVA should be greater than 10A, the output current of transformers above 120MVA should be greater than 20A, the output current of transformers above 180 MVA should be greater than 40A, and the output voltage should be as high as possible. The output voltage of the 10A transformer DC resistance tester shall not be less than 18V, and the output voltage of the 20A transformer DC resistance tester shall not be less than 25V.The output current of the instrument determines the measurement accuracy, and the output voltage of the instrument determines the measurement speed. Therefore, when choosing an instrument, it is important to understand the output voltage of the selected instrument. The instrument should have the function of directly converting the
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Gas chromatography detection method and judgment criteria
2025-05-12The oil chromatography analyzer under UHV power can help many power workers conduct various power tests more conveniently.Gas chromatography is a technique for separating and analyzing multi-component mixtures. It mainly utilizes the differences in boiling point, polarity, and adsorption coefficient of each component in the sample to separate the components inside the column, and conducts qualitative and quantitative analysis on the separated components.Chromatography analyzers use gas as the mobile phase (carrier gas). When the sample is sent to the injector and vaporized, it is carried by the carrier gas into the packed column or capillary column. The differences between components cause them to be separated in the chromatographic column, and then the detector behind the column sequentially detects the components based on their physical and chemical properties. After the conversion, the electrical signal is sent to the chromatograph. workstation. The chromatographic workstation recor
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Characteristics of on load tap changer tester for transformers
2025-05-09The on load tap changer tester under UHV power can help many power workers conduct various power tests more conveniently.1. Strong comprehensive measurement ability. One instrument can measure various quantities of on load tap changers. Such as switch selection, whether there is a breakpoint, transition waveform, transition time, transition resistance, three-phase synchronization, etc.2. More comprehensive analysis of measurement results. Users can analyze the resistance values and time of each point in the waveform, the time of each time period, and the three-phase of different phases through the large screen LCD display and function buttons. Through visual analysis, it is possible to understand the changes in various parameters of the three-phase switch at every moment during the switching process, and to analyze and compare waveform printing, storage, and historical waveforms.3. Print it out. The instrument is equipped with a front panel paper exchange printer, which can be directly
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Reasons and solutions for inaccurate grounding resistance testing in lightning protection detection
2025-05-09The grounding resistance tester under UHV power can help many power workers conduct various power tests more conveniently.In electrical lightning protection testing, many factors can lead to inaccurate readings of grounding resistance. In summary, there are generally several reasons.1. When inspecting high-rise buildings, using excessively long or thick wires can increase line resistance and induced voltage, resulting in measurement errors. At this time, wires with relatively low resistance should be used to minimize measurement errors as much as possible.2. The insertion depth of the iron drill should be greater than 1/4 of the length of the iron drill. Otherwise, testing errors may occur. So. During testing, the iron should be deepened as much as possible.3. In the case where the tested grounding electrode is "common ground", due to poor insulation or short circuit of the equipment, the grounding device generates a certain grounding voltage to the ground, making the reading unstable.
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Troubleshooting of Karl Fischer Titimeter
2025-05-08The trace moisture analyzer under UHV power can help many power workers conduct various power tests more conveniently.1、 Open circuit measurementWhen measuring an open circuit, the measurement status display and electrolysis status display will show the maximum. Excessive iodine is generated in the electrolyte of the anode chamber of the LED digital display meter, causing the color to darken. At this point, the following situations should be checked:1. Measure whether the plug and socket are in good contact.2. Measure whether the electrode leads are open and whether the plug is well soldered.2、 Open electrolysisWhen the electrolysis is turned on, the measurement status indicator light indicates, but the electrolysis status indicator light only lights up two green lights, and the "LED" digital tube does not count. At this point, the following conditions should be checked:1. Is the electrolytic plug in good contact with the socket.2. Whether the electrolytic leads on the cathode chamber
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Specific operating methods and test procedures for partial discharge test
2025-05-08The specialized production of partial discharge testers for UHV power can help many power workers conduct various power tests more conveniently.Partial discharge test is a non-destructive testing project. From the perspective of testing sequence, it should be placed after all insulation tests. Generally, the power frequency withstand voltage is used as the pre applied voltage for a few seconds, and then reduced to the partial discharge measurement voltage (usually a multiple of Um/√ 3, 1.5 times for transformers, and 1.1 to 1.2 times for transformers), with a duration of a few minutes. Measure partial discharge; Pre applied voltage refers to the overvoltage (such as lightning strikes) during simulated operation. The amount of partial discharge excited by pre applied voltage should not be continued by the partial discharge test voltage, that is, the amount of partial discharge excited when the system experiences overvoltage will not be prolonged by long-term operating voltageSpecific di
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Reasons for partial discharge during operation of high-voltage switchgear
2025-05-07The specialized production of partial discharge testers for UHV power can help many power workers conduct various power tests more conveniently.During the operation of power equipment, when partial discharge occurs, various charged particles such as electrons, positive and negative ions, etc., under the excitation of an electric field, generally have energy greater than the bond energy of polymers. These charged particles hitting the interstitial walls of the medium will break the chemical bonds of the insulator. At the same time, the heating of the medium at the partial discharge point will generate extremely high temperatures, which can cause thermal cracking of the insulator or promote oxidative cracking, thereby damaging the molecular structure of the insulator.High voltage switchgear is a combination of electrical appliances, composed of various materials such as epoxy resin, sulfur hexafluoride, and engineering plastics. There are many reasons for partial discharge, which can be
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What are the requirements for capacitive voltage dividers in a series resonance tester?
2025-05-07The AC series resonance system under UHV power can help many power workers conduct various power tests more conveniently.The capacitance deviation of the capacitive voltage divider should not exceed ± 5 of the rated value, and the ratio of the two-stage capacitance values should not be greater than 1.02 times the two-stage capacitance values.Temperature coefficient of capacitor voltage divider1) The temperature coefficient of the capacitor of the voltage divider should not exceed plus or minus 5 × 10-4K;2) The deviation of the voltage division ratio caused by the temperature coefficient of high and low voltage capacitors should not exceed 1/20 of the accuracy level limitThe insulation level of the capacitive voltage divider should be able to withstand 1.2 times the rated voltage for 1 minute without flashover or breakdown. The discharge performance of the capacitive voltage divider distributor should withstand the rated voltage discharge current and should not be damaged. The frequency
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Why can't the insulation resistance of water-cooled generators be measured with a regular megohmmeter
2025-05-06The insulation resistance tester under UHV power can help many power workers conduct various power tests more conveniently.1. It is not required to be in a water state when measuring insulation. When there is no water, the stator is qualified when measured with a vibration exciter of 2M or more; The coil water is not dry, measure it using the vibrating screen wiring method. After passing through water, the intelligent insulation resistance tester is a cold intelligent insulation resistance tester, and the motor insulation tester is 6M. The above are qualified.2. Due to the grounding of the external cold water pipeline, the shielding is the leakage current generated in the water after the vibration table is pressurized.3. The water collection ring and the external fixed cold water pipeline are insulated with connecting flanges.4. The operating conditions measured by the dual water dedicated vibrator are: the stator enters the water through the coil; The insulation resistance of the wate
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Cable fault tester accurately locates cable faults
2025-04-30The cable fault tester under UHV power can help many power workers conduct various power tests more conveniently.The power cable fault tester consists of three main parts: the power cable fault tester host, the cable fault locator, and the cable identifier. The host of the cable fault tester is used to measure the nature of cable faults, the total length and approximate location of the cable fault point at the testing end. The cable fault indication device determines the location of the cable fault point based on the approximate position of the cable fault tester host, in order to identify the cable fault point.For buried cables with unknown directions, a path meter is used to determine the underground direction of the cable. The basic method for testing power cable faults is to apply high-voltage pulses to the faulty power cable, causing a fault at the fault point of the cable. At the same time as the cable breaks through the breakdown point, electromagnetic waves are generated and so
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How to safely use the dielectric strength of insulating oil?
2025-04-30The specialized production of insulation oil dielectric strength tester for UHV power can help many power workers conduct various power tests more conveniently.1. Use a suitable power cord. Only use dedicated and compatible power cords.2. Connect and disconnect correctly. When connecting the test wire to the live terminal, do not connect or disconnect the test wire at will.3. Pay attention to the rated values of all terminals. To prevent fire or electric shock hazards, please pay attention to all ratings and markings. Before continuing with the connection, please read the instruction manual for more information about ratings.4. Use appropriate fuses. Only use fuses that meet the specified type and rating. Avoid contact with bare circuits and live metals. Do not touch exposed contacts and components when there is electricity.5. Do not operate in damp environments.6. To ensure operational safety, the high-voltage chamber of the instrument adopts a safety protection switch to prevent the
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Analysis of the Reasons for Unbalanced DC Resistance Testing of Transformers
2025-04-29The DC resistance tester under UHV power can help many power workers conduct various power tests more conveniently.In the DC resistance test of transformers, the DC resistance value of the winding will be unbalanced. The reasons can be divided into three situations: human factors, winding structure and material problems, and transformer defects.1. Human factors mainly include incorrect instrument selection, incorrect testing methods, and inadequate key testing points. These problems are mainly solved by improving the quality of personnel themselves.Unreasonable winding structure design and unqualified conductor materials can also lead to excessive DC resistance imbalance.2. Poor connection of internal structural components of transformerIf the winding leads are not well connected to the conductive rod or tap changer, or if the bushing cap has poor contact with the conductive rod, it will exceed the unbalanced DC resistance of the transformer. In this case, the DC resistance values of o
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What is the purpose of partial discharge test for transformers?
2025-04-29The specialized production of partial discharge testers for UHV power can help many power workers conduct various power tests more conveniently.Power transformers mainly use oil paper barrier insulation, which is composed of electrical paper and insulating oil. Due to the complex structure and uneven insulation of large transformers. When there are internal defects such as improper design, high local field strength, poor process or external factors, partial discharge will inevitably occur in transformers and gradually develop, ultimately causing transformer damage. Partial discharge inside power transformers mainly occurs in the following situations:(1) The oil paper isolation insulation in the middle of the winding breaks through the oil passage;(2) Fault in the oil passage at the end of the winding;(3) The oil gap between the insulated wire and the electrical paper (lead insulation, lap insulation, phase insulation) is broken down;(4) The vertical insulation oil passage between coils
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What is the principle of series excitation test transformer?
2025-04-28The AC series resonance test system under UHV power can help many power workers conduct various power tests more conveniently.The difference between a series excited test transformer and a regular test transformer is that more than two test transformers are connected in series for power on testing. Series testing of two or more test transformers is more flexible than testing a single transformer. This is because there are different voltage levels, and with the addition of test transformers, the voltage level required for the test can be more flexibly selected. So what is the principle of the series excitation test transformer? This article introduces to you.The principle of the series excitation test transformer is that, in addition to the high-voltage primary test transformer, the excitation winding is connected in series in the high-voltage winding. The parameters of this set of windings are consistent with the primary winding of the transformer tested later. Power the primary windin
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What are the specific functions of a power quality analyzer?
2025-04-27The power quality analyzer under UHV power can help many power workers conduct various power tests more conveniently.The power quality analyzer adopts advanced data acquisition and DSP technology, as well as on-site microcomputer display, storage, management, and communication technology, to achieve real-time measurement and storage of five power quality indicators and various commonly used electrical parameters Its main functions are as follows:1、 Test analysis function1. Basic parameter measurement: including three-phase voltage, current, power, power factor, etc2. Grid frequency3. Voltage (current) fundamental wave and harmonic amplitude, phase, power, impedance;4. Voltage deviation5. Voltage fluctuations and flicker, frequency spectrum analysis of amplitude modulation waveforms;6. Three phase voltage imbalance;2、 Data management functionStorage, retrieval, and remote transmission of data files such as test analysis results and statistical results.3、 Graphic functionOutput various v
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Under what circumstances will a gas chromatograph be used?
2025-04-27The oil chromatography analyzer under UHV power can help many power workers conduct various power tests more conveniently.In my daily work, I often hear the sound of a gas chromatograph. When will gas chromatography be used, as this instrument has a wide range of applications in many industries? Gas chromatograph is a computer controlled multi-purpose high-performance series chromatograph. Mainly used for quality inspection, scientific research, pollution inspection, and production control of industrial production intermediates and industrial products.Before using the gas chromatograph, open all glass ports of the titration cup and clean the titration cup, drying tube, and sealing plug with water. After cleaning, dry in an oven at approximately 80 ° C and then cool in a natural environment. Please note that the materials of the cathode chamber and measuring electrode should not be cleaned with water. Organic solvents such as acetone and methanol can be used for timely cleaning, and the
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Karl Fischer analysis for determining water content
2025-04-25The trace moisture analyzer under UHV power can help many power workers conduct various power tests more conveniently.Karl Fischer titration (KF) is a method in analytical chemistry that uses Coulombic, volumetric, or oven titration to determine trace levels of water content in a sample. The Karl Fischer titration method is very popular because it has multiple practical advantages compared to other moisture determination methods, such as accuracy, speed, and selectivity. KF has selectivity towards water because the titration reaction itself consumes water. On the contrary, the measurement of quality loss during drying will detect the loss of any volatile substances. KF has high precision and accuracy, typically within 1% of available water, such as 3.00% displayed as 2.97-3.03%. KF response is linear and usually takes only a few minutes to complete. Therefore, using a calibrated 1% water standard for single point calibration is sufficient, and there is no need to calibrate the curve.
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