Product List
Contact Us
Email：qiao@hvtest.cc
Mobile：+8615871365102
What's app：+8615871365102
-
What are the possible reasons for insulation failure of power equipment in withstand voltage testing?
2025-07-22Q: What are the possible reasons for the insulation failure of power equipment in the withstand voltage test?Answer: During the withstand voltage test, the possible reasons for the insulation failure of power equipment include:(1) Insulation degradation. For example, moisture in transformer oil, moisture in solid insulation, insulation aging, etc. can all lead to a decrease in insulation performance and may fail the withstand voltage test.(2) The testing method and voltage measurement method are incorrect. For example, during transformer testing, if the untested winding does not have a short circuit to ground, the untested winding may discharge to ground and be misjudged as unqualified. For example, when testing large capacity test objects, the voltage is still measured on the low voltage side. Due to the rising effect of capacitance, the actual voltage applied to the tested object exceeds the test voltage, causing the tested object to break down and be misjudged as unqualified.(3) Wit
MORE -
Abnormal phenomena and preliminary analysis in AC withstand voltage test
2025-07-221、 The situation reflected by regulatory agenciesWhen the power is turned on, the electromagnetic switch is turned on, and the voltage regulator is turned on, the voltage regulator will make a heavy sound. This may be due to the 220V voltage regulator being connected to the 380V power supply incorrectly. If the current reading is abnormal at this time, it may be due to the voltage regulator not being at zero position, or a short circuit or similar short circuit on the output side. Forgetting to remove the grounding rod is common.2、 The situation reflected by the voltmeter(1) The voltmeter indicates. After the power is turned on, the voltmeter immediately gives an indication that the voltage regulator is not at zero position. If the voltmeter has a large indication and a sound, it may immediately smell it.(2) The voltmeter shows no indication. After power on, the voltage regulator meter shows no indication. This may be caused by poor contact of the carbon brush in the autotransformer, a
MORE -
What are the advantages and characteristics of variable frequency series resonance?
2025-07-21What are the advantages and characteristics of variable frequency series resonance?1. The placement of variable frequency power supply is vertical and horizontal, which is particularly suitable for on-site operation and observation.2. Equipped with special shock-absorbing rubber support feet and protective aluminum boxes both inside and outside, it can effectively reduce bumps and vibrations during transportation and impact during lifting. Ensuring the long-term stability and reliability of the variable frequency power supply;3. Parameter display: The touch or external mouse LCD interface display system can display resonance voltage (i.e. the target voltage set before the test), test frequency, measurement frequency, low voltage voltage, low voltage current, withstand voltage time, overvoltage protection, overcurrent protection, flashover protection, voltage rise and stage timing, etc. The working mode switch capacitor, inductance, frequency exchange calculation, parameter query, etc.
MORE -
What are the functions of variable frequency series resonant devices
2025-07-21What are the functions of variable frequency series resonant devices1) Internally controlled by an embedded touch screen, the operation function has been optimized and the operation is simple2) Automatic frequency scanning to find resonance points The frequency range is 20-300Hz, and the sweep range can be manually set. The sweep time is 3 minutes (full frequency sweep) Frequency resolution 0.1Hz3) Automatic testing, users can set the testing program, and the system automatically completes the testing process according to the set program4) During automatic testing, the resonance state of the system is automatically tracked. When the resonance state changes beyond the set area, the system automatically tracks the resonance point Ensure that the system operates at output throughout the entire process, and plot the frequency voltage curve during frequency modulation.5) Automatically track the voltage during withstand voltage, and adjust the voltage to the target voltage when the voltage f
MORE -
What should be noted when using power frequency withstand voltage testing equipment
2025-07-18Series resonance testing equipment is widely used in cable withstand voltage testing, which can meet the testing requirements of cable handover testing and preventive testing, and has a small testing capacity. So what should be noted when using a series resonance test device for AC withstand voltage testing of high-voltage cross-linked cables?1. We can only conduct analysis tests after the cables to be tested have been installed in place and meet the development requirements for operation.2. The core wire of the test phase should be connected to a high voltage source, and the shielding layer of the test phase, non test phase core wire, and non test phase shielding layer should all be grounded. After confirming that the information is correct, the test can begin.3. The overvoltage protector of the cable shielding layer is short circuited, and the corresponding end cable metal shielding layer or metal sleeve is temporarily grounded.4. If the cable head is directly connected to the GIS, t
MORE -
How to determine whether the series resonant test sample has been broken down?
2025-07-18Whether the test sample has been punctured can be judged according to the following situations:1. According to the analysis of the meter connected during the experiment, in general, if the ammeter suddenly rises, it indicates that the test object has broken down (overcurrent relay action, automatic tripping). But when the ratio of the capacitance impedance XC of the test sample to the leakage impedance XL of the test transformer is not greater than 2, although the test sample breaks down, the ammeter reading will not change significantly, and sometimes the ammeter reading may even decrease.If this situation occurs, the voltage on the high voltage side should be monitored based on the measuring voltage device on the high voltage side. If the test sample breaks down, its voltmeter will only suddenly drop, and the voltmeter measured on the low voltage side will also drop, but sometimes it is not very obvious.2. Analyze based on the condition of the experimental control circuit. If the set
MORE -
Application of Frequency Conversion Series Resonance
2025-07-17In recent years, people's living standards have been increasing, and the demand for electricity resources has also been growing. In order to meet the power supply needs, high-voltage cross-linked cables have been widely used in the power system. To ensure the safe and stable operation of high-voltage cables, on-site completion handover tests must be conducted after cable laying is completed. Below, Dingsheng Power analyzes the application of variable frequency series resonance technology in cable high-voltage testing.Cable on-site handover test1. Test items and equipment wiringWhen measuring the insulation resistance of the outer sheath of the cable core, the measuring personnel should select a suitable range megohmmeter to measure the insulation resistance of the cable according to the actual situation, in order to determine whether the insulation resistance value of the cable meets the relevant requirements.When conducting the AC withstand voltage test of cable core wire to sheat
MORE -
Operating conditions and environmental requirements for frequency conversion series resonant withstand voltage device
2025-07-17Operating conditions and environmental requirements for frequency conversion series resonant withstand voltage device1、 Usage requirements: For indoor use.2、 Altitude: The operating area has an altitude not exceeding 1000m.3、 Beyond an altitude of 1000m, it shall be negotiated between the user and the manufacturer.1. Temperature range for series resonance test environment: The operating temperature range is -25 ℃~+45 ℃,2. Series resonance uses humidity: relative humidity does not exceed 80%.3. Seismic requirements: The resonant device should withstand an earthquake intensity of seven degrees without damage, that is, it should not be damaged under the action of horizontal acceleration of 0.15 minus vertical acceleration of 0.1g.Series resonance test, the variable frequency series resonance device mainly consists of a variable frequency controller, excitation transformer, high-voltage reactor, high-voltage voltage divider, etc. Variable frequency controllers are divided into two categori
MORE -
What is the role of a series resonant reactor in a resonant circuit?
2025-07-16As 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 resonant cir
MORE -
Detailed explanation of the differences between frequency modulation and induction series resonant voltage withstand devices
2025-07-16Power workers must strictly follow the testing procedures and regularly conduct AC withstand voltage tests on large electrical equipment, which requires the use of series resonant withstand voltage testing devices. Due to the high voltage and power capacity requirements of traditional power frequency withstand voltage test devices, which are bulky and heavy, they are not easy to transport. However, the series resonant withstand voltage test device can solve the disadvantages of traditional power frequency withstand voltage test devices, such as being difficult to transport and having poor flexibility. Therefore, the series resonant withstand voltage test device is widely used in AC withstand voltage tests of large electrical equipment, such as power transformers, power cables, hydroelectric generators, etc. The series resonance withstand voltage test device is divided into frequency modulation series resonance and inductive series resonance. So, what is the difference between frequency
MORE -
How to operate the AC withstand voltage device?
2025-07-15With the development of the power system, the capacity of operating equipment is increasing, such as thermal power generation units, which have a single unit capacity of over 1000MW, and hydroelectric power generation units, which have a maximum single unit capacity of 800MW. If traditional testing equipment (i.e. frequency test transformers) is used for the AC power frequency withstand voltage test of these devices, due to the large capacity required for the test, the test transformers and voltage regulators are very bulky, and it is difficult to solve the problem of large capacity test power supply on site, making on-site testing extremely inconvenient. The power frequency resonance device has great advantages in terms of test power capacity, equipment weight, test waveform, and investment. This device is mainly designed and manufactured for the AC withstand voltage test of hydraulic generators with a single unit capacity of 250MW and below.Test operation method for AC voltage withst
MORE -
Advantages of series resonant devices in power systems
2025-07-151. The required power capacity is greatly reduced. Series resonant power supply generates high voltage and high current through resonance between resonant reactor and the 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 experiment is only 1/Q of the test capacity.2. 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 system weight and volume, usually 1/10-1/30 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 pre
MORE -
Operation method of AC voltage withstand generator voltage withstand device
2025-07-14With the development of the power system, the capacity of operating equipment is increasing, such as thermal power generation units, which have a single unit capacity of over 1000MW, and hydroelectric power generation units, which have a maximum single unit capacity of 800MW. If traditional testing equipment (i.e. frequency test transformers) is used for the AC power frequency withstand voltage test of these devices, due to the large capacity required for the test, the test transformers and voltage regulators are very bulky, and it is difficult to solve the problem of large capacity test power supply on site, making on-site testing extremely inconvenient. The power frequency resonance device has great advantages in terms of test power capacity, equipment weight, test waveform, and investment. This device is mainly designed and manufactured for the AC withstand voltage test of hydraulic generators with a single unit capacity of 250MW and below.How to tune the generator AC withstand volt
MORE -
Advantages of verifying the power supply of resonant boost devices in power system applications
2025-07-14Advantages of verifying the power supply of resonant boost devices in power system applications:1. The required power capacity is greatly reduced. Series resonant power supply generates high voltage and high current through resonance between resonant reactor and the 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 experiment is only 1/Q of the test capacity.2. 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 system weight and volume, usually 1/5-1/10 of ordinary test devices.3. Improve the waveform of the output voltage. A resonant power supply is a resonant filtering circuit that can improve
MORE -
A comprehensive introduction to the characteristics of series resonance
2025-07-11Characteristics of series resonant system1. The automatic tuning function is powerful. When the system is automatically tuned, it automatically scans from 30Hz to 300Hz and displays the sweep curve, allowing users to intuitively see the system tuning process; After the frequency sweep is completed, the system performs a fine frequency sweep with a resolution of 0.01Hz within its ± 5Hz range based on the resonance frequency point preliminarily found by the sweep, and finally precisely locks the resonance frequency.2. Support multiple experimental modes The system supports test modes such as "automatic tuning+manual voltage regulation", "automatic tuning+automatic voltage regulation", "manual tuning+manual voltage regulation", etc. It is recommended to use the "automatic tuning+manual voltage regulation" mode, which can quickly find the resonance point and control the test process through manual voltage regulation, with higher safety.3. High stability and reliability. The system uses imp
MORE -
Precautions and troubleshooting for series resonance
2025-07-11matters needing attention:1. This test equipment should be used by high-voltage testing professionals. Before use, the user manual should be carefully read and repeatedly operated and trained.2. There should be no less than 2 operators. Strictly follow the safety operation regulations of our unit regarding high-voltage testing when using it.3. In order to ensure the safety and correctness of the test, in addition to being familiar with the product manual, it is also necessary to strictly follow the relevant national standards and regulations for the test operation.4. Each connecting wire must not be connected incorrectly, otherwise it may cause damage to the testing device5. When this device is in use, it outputs high voltage or ultra-high voltage, and must be reliably grounded to ensure safe operation.Common causes and troubleshooting:Fan cannot start:Failure to press' fault reset 'after emergency stop, fault protection, and mismatch protection; Internal temperature too high,
MORE -
Precautions for AC resonance testing system and variable frequency power supply system
2025-07-101.Before using the variable frequency power supply, it is necessary to carefully read this manual, especially the requirements in the precautions must be strictly followed, otherwise it may damage the variable frequency cabinet.2. This equipment must be operated by professionals, and special attention should be paid to safety during use.3. Due to the fact that the working power supply of the variable frequency power supply is directly obtained from the 380V AC power supply, without isolation treatment, the two output terminals of the variable frequency power supply cannot be directly grounded or short circuited, otherwise some components in the variable frequency power supply conversion cabinet will be damaged.4. The leakage protector must be removed from the working power supply, otherwise the ground leakage current during the start-up of the variable frequency power supply device will cause the leakage protection switch to operate and lose power.5.During the series resonance test, th
MORE -
Daily maintenance of series resonant variable frequency power supply
2025-07-101. Try to avoid working the variable frequency power supply device for a long time under severe detuning conditions.2. Regularly check the internal wiring of the inverter cabinet device and the tightening of screws at each contact to prevent loosening.3. The equipment should be stored in a dry, clean, and moisture resistant place. When not in use, cover with a dust cover to prevent dust from entering the cabinet through the air duct.4.During transportation, the frequency conversion cabinet should be secured with specialized straps to prevent loosening and slipping.5.When the frequency conversion cabinet malfunctions, please contact Wuhan Guodian Huamei Electrical Equipment Co., Ltd. in a timely manner.6. The display screen of the control box should not be exposed to sunlight, and the control box should have anti vibration measures during transportation.7. The connectors in the equipment are prone to damage. Be careful when using to prevent blockage by dirt.8. When using optical cables,
MORE -
Safety precautions for using AC/DC withstand voltage testing equipment
2025-07-09The arrangement of the AC/DC withstand voltage test device must ensure sufficient safety distance between people and their surroundings. Try to avoid placing equipment and high-voltage testing lines in personnel walkways as much as possible.The test site should be fenced and a "Stop! High Voltage Danger" sign should be hung.Testing high-voltage lines must have supporting or traction insulators. Protective devices should be installed at every interval and at the other end of the cable to prevent people from approaching and passing underneath.The microampere meter for DC high voltage testing should be at a high potential. In addition to the shielding box, there should also be an automatic overcurrent protection device to prevent the instrument from suddenly breaking down, short circuiting, or burning out during discharge.Power frequency withstand voltage test, please pay attention to checking whether the equipment capacity is sufficient to avoid resonance.The working grounding wire (high
MORE -
Comparison between Parallel Power Supply and Series Power Supply
2025-07-09Parallel resonant intermediate frequency power supply is the mainstream intermediate frequency power supply in China, which adopts parallel resonant inverter technology. This technology originated from the former Soviet Union. The power supply has low technical requirements for components, and there are many manufacturers of supporting components. The manufacturing cost of the power supply is low, and its performance is stable. Especially, the popularity of medium frequency furnaces with small and medium capacities is high. However, with the continuous improvement of energy conservation and consumption reduction requirements, the shortcomings of this technology are increasingly being concerned by people. Its main manifestations are:(1) The power regulation of low power factor parallel inverters mainly relies on changing the rectified voltage of the three-phase fully controlled bridge. When the control pulse a of the rectifier bridge is ≤ 0 ° (DC voltage is lower than the maximum value)
MORE
