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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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Procedure for using grounding resistance tester
2025-03-12The grounding resistance tester under UHV power can help many power workers conduct various power tests more conveniently.1、 Preparation work1. Carefully read the user manual of the grounding resistance tester, familiarize yourself with the structure, performance, and operation methods of the grounding resistance tester.2. All measuring tools and accessories must be prepared, instruments and grounding probes must be wiped, especially grounding probes, and dirt and rust affecting conductivity on their surfaces must be removed.3. Disconnect the connection point between the grounding main line and the grounding body, or the connection point of all grounding branches on the grounding main line, so that the grounding body is disconnected from any connection and becomes an independent body.Preparation work is an important task before measurement. If these preparations are not made, it is likely that the measurement will not proceed smoothly or the measurement results will not be accurate eno
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Explanation of Common Terminology for High Voltage Test Equipment
2025-03-12The DC high voltage generator under the UHV power can help many power workers conduct various power tests more conveniently.In order to help you have a more comprehensive understanding of high-voltage testing, manufacturers of high-voltage testing equipment have organized explanations of commonly used terms for high-voltage testing equipment, hoping to be helpful to you.1. Dielectric: also known as insulating material, abbreviated as insulation, is one of the most widely used materials in electrical engineering.2. Insulation resistance: The resistance corresponding to the leakage current flowing through a dielectric after applying a DC voltage for a certain period of time.3. Absorption ratio: The ratio of the insulation resistance value at 60 seconds to the insulation resistance value at 15 seconds in the same experiment.4. Polarization index: The ratio of the insulation resistance value at 10 minutes to the insulation resistance value at 1 minute in the same experiment.5. Dielectric l
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How to choose a grounding resistance tester
2025-03-11The grounding resistance tester under UHV power can help many power workers conduct various power tests more conveniently.The grounding resistance tester is a commonly used instrument for measuring grounding resistance, and is also an indispensable tool for electrical safety inspection and completion acceptance of grounding engineering. With the rapid development of computer technology, grounding resistance testers have penetrated into many microprocessor technologies, and their measurement functions, content, and accuracy are unparalleled. The grounding resistance tester adopts a new clamp method, which can directly measure online without the need for pile driving and wiring. Controlled by a microprocessor, it automatically detects the connection status of each interface and the interference voltage and frequency of the grounding grid, with unique numerical retention and intelligent prompt functions.Selection of grounding resistance tester:1. At present, intelligent grounding resistan
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Series resonant overvoltage and its conditional characteristics
2025-03-11The series resonance under UHV power can help many power workers conduct various power tests more conveniently.In the power system, some inductive and capacitive components can form various oscillation circuits during system operation or failure. Under certain energy sources, series resonance phenomena can occur, leading to severe overvoltage in certain components of the system.classification(1) The linear resonant overvoltage resonant circuit is composed of inductive elements without iron cores (such as the inductance of transmission lines and leakage inductance of transformers) or inductive elements with iron cores that have excitation characteristics close to linearity (such as arc suppression coils) and capacitive elements in the system.(2) The ferromagnetic resonance overvoltage resonance circuit is composed of inductive components with iron cores (such as no-load transformers and voltage transformers) and capacitive components of the system. Due to the saturation phenomenon of ir
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Characteristics of Transformer Capacity Characteristics Tester
2025-03-10The UHV power professional production transformer capacity tester can help many power workers conduct various power tests more conveniently.1. Can accurately measure the capacity of various distribution transformers, passive measurement, convenient and accurate.2. Equipped with an internal power supply, it automatically generates a three-phase high-power test power supply.3. It can measure the no-load current, no-load loss, short-circuit voltage, and short-circuit loss of various transformers.4. It can automatically perform waveform distortion correction, temperature correction, voltage correction, and current correction (short-circuit testing under non rated current conditions). Operators only need to input calibration indicators according to the transformer type to automatically calculate the corrected results. It is very suitable for units without short-circuit testing conditions for slightly larger transformers.5. Voltage circuit width limit: The maximum voltage can be measured up
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Explain the working principle and application of DC resistance tester
2025-03-07The DC resistance tester under UHV power can help many power workers conduct various power tests more conveniently.The measurement of DC resistance in transformer windings is an important part of its daily testing. By measuring the DC resistance, it is possible to check the quality of the coil, whether the contact position of the tap changer is good, whether the coil or lead is broken, whether the parallel branch is correct, and whether there is a short circuit phenomenon, which is an important data for determining the short-circuit loss. Therefore, this experiment should be conducted after the handover, pre testing, major repair, and replacement of the tap changer. In recent years, with the continuous increase of power system capacity, transformer capacity has also been increasing. The larger the transformer capacity, the higher the voltage level, and the greater the ratio of inductance to resistance. Therefore, the stability time of a large transformer winding DC circuit may be sever
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Precautions for using high-frequency DC high voltage generator
2025-03-07The DC high-voltage generator under the UHV power company can help many power workers conduct various power tests more conveniently.1. Personnel using high-frequency DC high voltage generators must have a professional with a High Voltage Test Certificate.2. When using this instrument, users must comply with the provisions of 168 "Power Safety Regulations" and install two obvious disconnection points before entering the testing instrument with the working power supply. When replacing samples and wiring, it is necessary to clearly disconnect the two power disconnection points.3. Before testing, please check if all test wiring, control boxes, multiplier tubes, and grounding wires of the tested product are connected correctly. The ground wire of the test circuit should be grounded at a single point according to the requirements of this instrument manual.4. Special discharge resistor rod is used for discharging large capacitor samples. Do not immediately come into contact with the test obje
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Operation method of closed flash point tester
2025-03-06The closed flash point tester under UHV power can help many power workers conduct various power tests more conveniently.Usage and operation steps:1. Instrument installation:(1) Open the instrument packaging and check for damage;(2) Check the instrument model and accessories according to the packing list;(3) Debugging can only be carried out after the instrument is checked for accuracy.2. Power on preparation:(1) Insert the power cord into an AC220V three pin socket;(2) Clean the test oil cup with petroleum ether.3. Test program:(1) Turn on the power switch and display the screen;(2) Press the enter system (play) button to display the screen;(3) Press the (self-test) button to enter the self-test interface; Press the (arm lift) button, and the arm will automatically stop when it reaches its maximum height.(4) Put the test oil sample into a cleaned oil cup to the specified mark, place it in the heating bath cover, and then press the (lower arm) button. When the lower arm descends
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Daily maintenance of partial discharge tester
2025-03-05The specialized production of partial discharge testers for UHV power can help many power workers conduct various power tests more conveniently.Partial discharge detectors are used in many industries, and due to different industries, the frequency and environment of use also vary. Usually, in order to ensure accurate detection results and extend the service life of the detector, it is necessary to pay attention to maintenance in daily use. Today, we will carry out daily maintenance work for partial discharge detectors.1、 The moisture-proof work of partial discharge detectors must be taken into account, especially in areas with humid climate. The equipment should be stored in a dry place. If not used for a long time, it should be powered on twice a month for two hours before use to dissipate moisture. Usually used when stored in a place without corrosive gases and substances, the humidity should not exceed 85%.2、 Partial discharge testers can work outdoors in many situations. It is reco
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