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Measures to reduce soil resistivity
2025-03-31The grounding resistance tester under UHV power can help many power workers conduct various power tests more conveniently.When the soil resistivity at the grounding point (such as rock, sand, and permafrost) is high, measures must be taken to reduce the soil resistivity in order to meet the grounding resistance requirements. These measures include(1) Replace the soil with low resistivity black soil, clay, and sandy clay, and replace it with high resistivity soil. Generally, the soil should be replaced within 1/3 of the upper length of the grounding body and within a range of 0.5 meters around it.(2) If the soil resistivity in the deep part of the grounding point is low, the burial depth of the grounding body can be appropriately increased. Deep burial can also ignore the effect of soil freeze-drying on the increase of electrical resistivity.(3) External lead grounding, burying the grounding body in a low soil resistivity area nearby through metal leads.(4) Chemical treatment involves a
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Why is the test current of the circuit resistance tester at least 100A?
2025-03-28The circuit resistance tester under UHV power can help many power workers conduct various power tests more conveniently.The circuit resistance tester is designed by combining digital circuit technology and switching power supply technology. The circuit resistance tester is suitable for measuring the contact resistance and circuit resistance of switch control equipment. The test current is DC 100A recommended by the national standard. The circuit resistance and contact resistance can be directly measured and digitally displayed at 100A current.Why does the regulation require the use of at least 100A DC current to detect switch circuit resistance?1. Firstly, because there is an oxide film between the switch contacts, if a smaller current is used for detection, the test results will generally be much larger due to the influence of the oxide film, but the oxide film can be broken down under high current. In theory, as long as the test current does not exceed the rated current, the larger t
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What are the advantages of zinc oxide lightning arrester?
2025-03-28The zinc oxide lightning arrester tester under UHV power can help many power workers conduct various power tests more conveniently.1. Zinc oxide lightning arrester has a large current capacityThis is mainly reflected in the ability of lightning arresters to absorb various lightning overvoltages, power frequency transient overvoltages, and operating overvoltages. Tuopu Electric's current carrying capacity fully meets or even exceeds the requirements of national standards. The discharge level, energy absorption capacity, 4/10 nanosecond high current tolerance, and 2ms square wave current capability of the circuit have all reached the advanced level in China.2. Zinc oxide lightning arrester has excellent protection characteristicsZinc oxide lightning arrester is an electrical product used to protect various electrical equipment in the power system from overvoltage damage, with good protection performance. Due to the excellent nonlinear volt ampere characteristics of zinc oxide valve p
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Insulator salt density test
2025-03-27The insulator tester under UHV power can help many power workers conduct various power tests more conveniently.Related terms:1. Reference cap and pin insulatorXP-70, XP-160, LXP-70, and LXP-160 ordinary disc suspension insulators (according to GB/T 7253) are usually measured for site pollution level using 7-9 strings.2. Creepage distanceThe shortest distance between two conductive parts along the surface of the insulator.Note: The surface of cement or other non insulating bonding materials is not considered a component of the creepage distance. If some parts of the insulation of the insulator are covered with a high resistance layer, that part should be considered as the effective insulation surface, and the distance along that part should be included in the creepage distance.3. Unified Specific Creepage Distance (USCD)The ratio of the creepage distance of an insulator to the maximum operating voltage it can withstand at both ends (the highest phase voltage in AC systems), mm/kV。4. Sal
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What are the high-voltage testing projects?
2025-03-26The insulation resistance tester under UHV power can help many power workers conduct various power tests more conveniently.As a means of checking whether electrical equipment can operate normally, high-voltage testing is widely used. What are the high-voltage testing projects? What are the corresponding high-voltage testing equipment?1. Insulation testing of coil equipmentThe tests include: insulation resistance, absorption ratio (polarization index) test, leakage current test, dielectric loss tangent Tan δ test, external power frequency withstand voltage test, induction withstand voltage test, and partial discharge test.The high-voltage testing equipment used includes: digital display meter, fully automatic dielectric loss tester, complete set of power frequency withstand voltage testing device, induction withstand voltage testing device, partial discharge detector, etc.2. Characteristic testing of coil equipmentThe testing includes: ratio, polarity and wiring group testing, DC resist
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Precautions for selecting and testing transformers
2025-03-26The professional production of high-voltage test transformers in UHV power can help many power workers conduct various power tests more conveniently.Choose a test transformer? Do you want to buy a cost-effective test transformer? The following items should be considered, and we will briefly introduce them to you below.1、 Determine requirementsThe selection of test transformers needs to determine the required product performance based on the characteristics of each industry before procurement. This can ensure that the purchased products meet the requirements and avoid the hassle of switching back and forth.2、 Select modelUsually, there are multiple types of test transformers that can meet the requirements. Therefore, it is necessary to make a comprehensive decision based on the differences and prices between them. Choose products with high cost-effectiveness. Compared with traditional oil immersed lightweight test transformers, inflatable test transformers reduce weight by 40-65% (depen
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Voltage frequency characteristics of magnetic system in waveform recorder
2025-03-25The waveform recorder under UHV power can help many power workers conduct various power tests more conveniently.1. OverviewThe test procedure for the voltage frequency characteristics of the excitation system is as follows:Click on the excitation system voltage frequency characteristic button on the main interface ->Set test parameters ->Set oscilloscope environment ->Channel calibration ->Start test ->End test ->Test data analysis and processing2. ApplicationThe voltage frequency characteristic test of the excitation system is used to evaluate the generator excitation system and draw a relationship diagram between the excitation system voltage and frequency.3. Test connectionConnect the test line to the parameter setting interface according to the relationship diagram to obtain the test signal1> Connect the unit frequency transmitter signal to the instrument signal input channel CH12> Connect the PT secondary side of the A camera terminal voltage to the CH2 channel of the instrumentTh
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Load suppression test for waveform recorder
2025-03-25The waveform recorder under UHV power can help many power workers conduct various power tests more conveniently.overviewThe procedure for load rejection test is as follows:Click the load suppression test button on the main interface ->Set test parameters ->Set oscilloscope environment ->Channel calibration ->Start test ->End test ->Test data analysis and processingapplicationThe load rejection test template is used for data recording and automatic calculation of test result parameters during the load rejection test process of steam turbine generators or hydro generator systemsTEST CONNECTION1> Connect the voltage PT secondary side of camera terminal A to the CH1 channel of the instrument2> Connect the unit frequency transmission signal to the CH2 channel of the instrument3> Connect the opening signal of the passive circuit breaker to the switch channel SW1 of the instrumentTest parameter settingsThe sampling frequency of the generator load suppression tester is 25kHz, the oscilloscope
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Preparation work for transformer winding deformation testing machine before testing
2025-03-24The UHV power professional production transformer winding deformation tester can help many power workers conduct various power tests more conveniently.1) The tested transformer must be completely isolated from the power grid, and all coil leads must be disconnected from the busbar and kept away from the transformer terminals. Transformer winding deformation detection must be carried out before the DC test project or after the transformer winding is completely discharged, otherwise it will affect the repeatability of the test data and even cause damage to the test instrument.2) The amplitude frequency response characteristics of transformer windings are related to the position of the tap changer. The test should be conducted at the highest tap position, or the tap changer should be in the same position for each test.3) All wiring should be firm and reliable.4) The BNC end of the test cable is connected to the BNC end of the same color code on the host, and the red and yellow test clips
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Basic knowledge of contact resistance for contact resistance tester
2025-03-21The circuit resistance tester under UHV power can help many power workers conduct various power tests more conveniently.1. What is contact resistance?Contact resistance is the additional resistance when static contact and dynamic contact come into contact with each other.2. Partial contact resistance of circuit breakerAnti shrinkage and surface resistance of dynamic and static contact3. Reasons for unqualified contact resistance of circuit breakersWhen disconnecting high short-circuit current, the contact burns out.Improper adjustment can cause changes in travel and result in serious non-compliance when exceeding travel limits, leading to changes in contact pressure or contact area.After the circuit breaker is installed and commissioned, it is not put into operation for a long time. The dynamic and static contact surfaces are oxidized, and the contact surface resistance increases.Long term operation causes deformation of the spring and a decrease in contact pressure.Physical deteriorat
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Important note on the calibration device of high-voltage switch tester
2025-03-21The circuit breaker tester under UHV power can help many power workers conduct various power tests more conveniently.1. The high-voltage switch tester calibration device can only be used to verify switch testers used for metal contact testing, and does not include switch testers with closed resistance fracture and graphite contact fracture. Generally speaking, the breaking voltage of metal contacts is less than or equal to DC24V, and the breaking voltage of closing resistors is greater than DC24V. The principle of graphite contact is constant current source output, which cannot be detected by conventional methods. If the instrument has a closed door resistor function inside, the metal contact channel of the instrument can be tested. Please consult the manufacturer of the calibration device for details.2. Method for detecting the voltage of switch circuit breakers. When the circuit breaker of the switchgear is in the open state, use the DC gear of the multimeter to detect the voltage ou
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Common problems and solutions for circuit breaker testers
2025-03-20The circuit breaker tester under UHV power can help many power workers conduct various power tests more conveniently.During the on-site closing/opening operation, the switch did not move.The wiring of the closing/opening control is incorrect or there is a problem with the control circuit.Solution: Find the control wiring diagram of the on-site control cabinet, ask the relevant operators, locate the closing and opening coils and switch auxiliary wiring terminals, and rewire according to Appendix 2 of this manual's control wiring diagram and instructions. Check the control circuit to ensure that it is smooth.The instrument displays' output short circuit or overload, please turn off and check the control wiring '(1) Control wiring error caused output short circuit, activated short circuit protection function, "closing/opening control power supply" has no output.Solution: Turn off the instrument and recheck the wiring according to item 1.The excitation coil is overloaded and th
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Factors affecting the accuracy of insulation resistance tester
2025-03-19The insulation resistance tester under UHV power can help many power workers conduct various power tests more conveniently.Electricians often need to use insulation resistance testers in their work. The main function of this device is to test the insulation resistance of transformers, mutual inductors, generators, high-voltage motors, power capacitors, power cables, lightning arresters, etc. It has the characteristics of easy use and high accuracy. But sometimes it's difficult to get results when many people use it for the first time. What are the factors that affect the accuracy of insulation resistance testers?Generally speaking, the resistance of materials decreases with increasing temperature and humidity in the environment. Compared to enterprises, surface resistance (rate) is sensitive to environmental and humidity data, while body resistance (rate) is sensitive to temperature changes. Humidity will increase, surface information leakage will increase, and volumetric conductiv
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The high-voltage switch dynamic characteristic tester cannot be driven normally
2025-03-19The circuit breaker tester under UHV power can help many power workers conduct various power tests more conveniently.The high-voltage switch dynamic characteristic tester prompts "Output short circuit or excessive load, please shut down and check the control wiring"The control wiring error caused a short circuit in the instrument output, which activated the short-circuit protection function. The high-voltage switch dynamic characteristic tester had no output when the control power was turned on or off.Solution: After shutting down, refer to the user manual for the first wiring check.The excitation coil is overloaded, and the high-voltage switch dynamic characteristic tester cannot be driven normallyTreatment method:1. For the switch of electromagnetic mechanism, the driving current required for the closing coil of the switch is very large (up to 100A or several hundred amperes), and the carrying capacity of the instrument operation power supply is 20A. Causing the high-voltage switch d
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Characteristics and Applications of VLF High Voltage Generator
2025-03-18The very low frequency high voltage generator under the UHV power can help many power workers conduct various power tests more conveniently.Very low frequency high-voltage generators are generally used for voltage withstand tests of power cables and can also be used for insulation voltage withstand tests of large power transformers.Its characteristic is that it has no damage to the tested cable, and can also test cables that have begun to age but are still usable. It is a non-destructive voltage testing method.This test more accurately determines the connection errors of new and repaired cables at their joints and ends than DC high voltage testing.Industry standard "Test method for very low frequency (0.1Hz) voltage of xLPE insulated power cables below 35kV". According to the requirements of this industry standard, the testing procedure is as follows:All electrical equipment connected to the test product should be separated from the test cable, and the test equipment (very low frequenc
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Design requirements for microcomputer relay protection devices
2025-03-18The relay protection tester under UHV power can help many power workers conduct various power tests more conveniently.Design requirements for microcomputer relay protection device:(1) The microcomputer relay protection device should have the ability to resist electromagnetic interference.(2) The microcomputer relay protection device should be equipped with online automatic detection. In the microcomputer relay protection device, when any damage occurs to the microcomputer part, an abnormal device message should be sent out and the corresponding protection should be automatically locked when necessary. But the design of the outlet circuit of the protective device should be simple, and it is not advisable to add components that may reduce safety in the circuit to achieve complete self inspection of the outlet circuit.(3) All output terminals of the microcomputer relay protection device should not be electrically connected to its weak current system.(4) The microcomputer relay protection
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Main functions of circuit breaker characteristic tester
2025-03-17The circuit breaker tester under UHV power can help many power workers conduct various power tests more conveniently.According to the GB10963-1999 "Overcurrent Protection Circuit Breakers for Household and Similar Places" standard, conduct a trip characteristic test on the circuit breaker.1) Time current characteristic testFrom the cold state, the circuit breaker should not trip when powered with a current of 1.13In (contracted non trip current) until the agreed time. Then, within 5 seconds, the current should be steadily increased to 1.45 In (the agreed tripping current), and the circuit breaker should trip within the agreed time.Starting from the cold state, the current of the circuit breaker should be 2.55In, and the disconnection time should be greater than 1s. The disconnection time of circuit breakers with rated current less than or equal to 63A should be less than 60s, and for open circuits with rated current greater than 63A. The disconnection time should be less than 120 secon
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Precautions for Transformer Winding Deformation Testing Machine
2025-03-14The UHV power professional production transformer winding deformation tester can help many power workers conduct various power tests more conveniently.Precautions for determining transformer winding deformation:a) The necessary conditions for transformer winding deformation are outlet short circuit, near-field short circuit, multiple overcurrent actions, and collisions during transportation;b) The frequency response curves of the low-frequency part (tens of kHz) can generally overlap well, otherwise it is suspected that the test wiring has poor contact;c) Generally speaking, transformers of 35kV and below (including those undergoing factory renovation) may have poor frequency response characteristics, and original data comparison should be retained during handover;d) The measured frequency response curve is generally between+20 and -80 dB. If exceeded, check whether the test circuit has poor contact or disconnection;e) When the angle winding is tested separately, the three-phase freque
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Product features of transformer no-load loss tester
2025-03-14The UHV power professional production transformer capacity tester can help many power workers conduct various power tests more conveniently.1. It can measure the no-load current, no-load loss, impedance voltage, load loss, and zero sequence impedance of various transformers.2. It can automatically perform waveform distortion correction, temperature correction (providing simple temperature correction and additional loss correction respectively), voltage correction (no-load testing under non rated voltage), and current correction (short-circuit testing under non rated current conditions), which is very suitable for units with slightly larger capacity transformers that do not have short-circuit testing conditions3. It can measure three-phase voltage, three-phase current, average voltage, average current, two-phase active power (due to the two-phase meter method, only the power of phases A and C are displayed here), total power4. It can measure the 2-42nd harmonic content of each phase vol
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Analysis of the advantages and disadvantages of DC and AC in cable withstand voltage testing
2025-03-13The AC resonant test set under UHV power can help many power workers conduct various power tests more conveniently.The two methods of cable withstand voltage testing, AC and DC, each have their own advantages and disadvantages for reference.1、 Cable DC withstand voltage test1. Advantages:If the cable adopts DC withstand voltage method, the leakage current will be very small, and the power of the DC high-voltage generator is also relatively small, so the equipment is lightweight and easy to carry;2. Disadvantages:When using direct current for cable withstand voltage, parasitic charges are easily generated, and the higher the voltage, the greater the charge, and discharge cannot solve the problem at all. Practice has proven that there are many good local insulation problems in cables when conducting DC withstand voltage tests on 35kV and above. At present, AC testing is mandatory for cables of 35kV and above. The DC withstand voltage test is destructive to the cable, and the cable should
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