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AC Resonant Test Equipment

What is AC Resonant Test Equipment

Our AC resonant test equipment enable tests to all commonly standards (VDE, EN, IEC, etc.). The products impress with a variety of technical features: TFT display, Ethernet interface, automatic test sequence to a fully electronic generator for even faster and more accurate tests.

Benefits of AC Resonant Test Equipment

Significant reduction in required power capacity:
When the AC resonant test equipment is in operation, its required power supply is only 1/Q of the test capacity, which means that compared with traditional test devices, it can greatly save electricity and improve energy efficiency.

Significant reduction in volume and weight:
The volume and weight of this type of equipment are usually only 1/10 to 1/30 of that of a regular testing device, so it has good transportation performance and is easy to carry and operate.

Improve output voltage waveform:
Due to the fact that the circuit of the AC resonant test equipment is a filtering circuit, it has good stability performance, can output smoother and more stable voltage waveforms, and improve the accuracy and reliability of the test.

Superior protection performance for the test object:
During the experiment, the short-circuit current of the AC resonant test equipment is only 1/Q of the normal test current, which helps to prevent large short-circuit currents from burning the fault point and protecting the test object from damage. At the same time, the device will not experience recovery overvoltage, further enhancing the protective performance of the test object.

Equipped with advanced digital and power technologies:
The AC resonant test equipment adopts advanced technologies such as intelligent power modules, significantly improving the reliability of the entire machine while reducing the size and weight of the equipment.

Unique and aesthetically pleasing structural design:
The frequency modulation power control box of the equipment adopts two methods: plug-in and screw connection, which is both safe and convenient. The reactor adopts a unique epoxy casting process, which is not only moisture-proof and shockproof, but also has a beautiful and elegant appearance.

Complete protection functions:
The equipment has multiple protection functions, such as overvoltage protection, overcurrent protection, overheating protection, etc. These protection measures can quickly act in case of equipment abnormalities, ensuring the safety of the equipment and the test object.
AC resonant test equipment has been widely used in AC withstand voltage tests in industries such as power, metallurgy, petroleum, and chemical engineering due to its advantages of high efficiency, energy conservation, portability, stable output, superior protection performance, advanced digital and power technology, and complete protection functions.

Why Choose us

Customized solutions

We understand that each client's needs are unique, so we can tailor solutions to meet your specific requirements to meet individual client needs.

Quality control

We strictly abide by the international quality management system and strictly control every link from raw material procurement, production process, product quality inspection, etc. to ensure the stability and reliability of our products and services.

Our service

The company has a professional sales team to provide you with high-quality pre-sales consulting services. During the order production process, customers can communicate with us at any time to understand the production progress. At the same time, we provide high-quality after-sales service to meet the different needs of customers.

How to use AC Resonant Test Equipment to conduct tests on transformers

Connect the transformer:Firstly,correctly connect the transformer to be tested to the AC resonant test equipment.Ensure the connection is correct to avoid equipment damage or safety hazards.

Set test parameters:Based on the transformer's specifications and the parameters to be tested,set the frequency,voltage,and other relevant parameters of the AC resonant test equipment.These parameters will help the transformer and the test device to reach a resonant state.

Start the test:Start the AC resonant test equipment and begin the test.During the test,monitor the transformer's response and performance,including parameters such as inductance and losses.

Data recording and analysis:During the test,record the test data and perform analysis.By analyzing the data,the transformer's performance can be evaluated,issues can be identified,and adjustments can be made.

Conclusion and report:Draw conclusions based on the test results and write a test report.The report should include the purpose of the test,test methods,test results,and conclusions.

What are the specifications and configurations of AC Resonant Test Equipment

- Voltage range: Typically up to several hundred kilovolts, depending on the application.

- Frequency range: Usually from a few hertz to several kilohertz.

- Power rating: Ranging from a few kilowatts to several megawatts.

- Test object size: Systems can be designed to accommodate various sizes of test objects, from small components to large power transformers.

- Resonant frequency: The system is designed to operate at a specific resonant frequency, which can be adjusted as needed for different tests.

- Control and monitoring: The system is typically equipped with a control panel for setting test parameters and monitoring test progress.

- Safety features: AC resonant test equipment are designed with safety features such as interlocks, grounding systems, and emergency stop buttons to ensure the safety of operators and equipment.

Variable Frequency Resonant Ac Hipot Tester

What are the types of AC Resonant Test Equipment?

AC withstand voltage resonance test device:
This type of equipment can meet the AC withstand voltage test of capacitive equipment such as transformers, GIS systems, SF6 switches, cables, and bushings according to regulatory requirements. It can meet the requirements of high voltage and low current equipment testing conditions, as well as low voltage and high current equipment testing conditions, so it has a wide range of applications.

Variable frequency series resonance test device:
This is a cable specific AC resonant test equipment that adjusts the frequency of the power supply to achieve resonance between the reactor and the tested capacitor, thereby obtaining high voltage and large current on the tested object. This method has been widely used in the withstand voltage test of various types of cables up to 35KV both domestically and internationally.

Resonance testing device for CVT inspection:
This includes resonant boost devices for CVT inspection, variable frequency resonance, variable frequency series resonance, series resonance transformers, etc., mainly used for the inspection and testing of CVT (capacitive voltage transformers).

In addition, from the perspective of output parameters, AC resonant test equipment can be divided into high voltage and high current types. High voltage type is mainly used for equipment such as ultra-high voltage GIS, high-voltage circuit breakers, transformers, cables, and coupling capacitors; High current type is suitable for large capacity equipment such as water turbines, steam turbine generators, distribution network cables, and power capacitors.

From the perspective of tuning methods, it can be divided into sensing type and frequency modulation type. Inductive regulation type is to change the inductive reactive power capacity by adjusting the inductance of the reactor, so that it is as equal as possible to the capacitive reactive power capacity value in the series circuit, so that the circuit reaches a resonant state; The frequency modulation type is to fix the inductance of the reactor, adjust the frequency of the resonant circuit, and make the inductive reactive power capacity value as equal as possible to the capacitive reactive power capacity value at the same frequency, achieving the resonant state of the circuit.

AC resonant test equipment is suitable for AC withstand voltage test of transformer, circuit breaker, switch, GIS system, cable, bushing, insulator and other equipment. It has the functions of high voltage over-voltage protection, low voltage over-current protection, detuning protection, zero position protection, flashover protection, emergency shutdown, under-voltage protection and so on. It not only meets the requirements of equipment test conditions for high voltage and small current, but also meets the requirements of equipment test conditions for low voltage and large current, and has a wide application range.

What Are The Main Applications Of AC Resonant Test Equipment?

Application in cable testing

The extensive use of cables in urban and rural power grids often leads to faults. To ensure the safe operation of cross-linked cables, State Grid Corporation of China has made new regulations on cable handover and preventive testing, replacing the original DC withstand voltage test with AC withstand voltage test to avoid the cumulative effect of DC test causing damage to cables.
Many cables have successfully undergone DC withstand voltage tests according to the GB50150-2006 standard during the handover test, but insulation breakdown accidents occurred shortly after being put into operation, and normal operating cables have also been damaged by DC withstand voltage tests. The AC withstand voltage test is effective for cables as its electric field distribution conforms to the actual operating conditions.
Usually, the capacitance of AC power cables is large, and the test current is also large. The volume of inductive devices will be very large, and inductance adjustment will be difficult. On the other hand, frequency modulation devices are more flexible and easier to implement. Therefore, on-site AC withstand voltage testing of cables often utilizes AC resonant test equipment.

Application in GIS equipment

After the overall assembly of gas insulated switchgear in the factory is completed or adjusted and tested in units, it is transported to the site for installation in units after passing the test. Vibration, impact, and other factors during transportation may cause loosening or displacement of the internal fasteners of GIS components or assemblies; During the installation process, there may be errors in connection, sealing, and other process treatments, resulting in scratches or misalignment of the electrode surface, leading to electrode surface defects; The installation site may introduce suspended dust from the air. Conductive particles and impurities, which are difficult to detect through routine tests at the installation site, pose a great threat to the safe operation of GIS.
Due to limitations in testing equipment and conditions, most early GIS products did not undergo strict on-site voltage withstand tests. Accident statistics indicate that most GIS systems that did not undergo on-site voltage withstand tests have experienced accidents. Therefore, GIS must undergo on-site voltage withstand tests.
The on-site withstand voltage of GIS mainly includes three testing methods: AC voltage, oscillation operation impulse voltage, and oscillation lightning impulse voltage. The AC withstand voltage test is a common method for GIS on-site withstand voltage testing, which can effectively detect abnormal electric field structures (such as electrode damage).
At present, due to limitations in testing equipment and conditions, only AC voltage withstand tests are generally conducted on site. IEC517 and GB7674 recognize that the voltage frequency of SF6 gas insulation test is basically equivalent to the power frequency voltage test in the range of 10-300Hz. Both domestically and internationally, AC resonant test equipment are mostly used for GIS on-site AC withstand voltage testing.

Application in AC withstand voltage test of generators (motors)

The stator winding of a generator has a large capacitance to ground or between phases, for example, the stator winding of a 300MW hydroelectric generator has a capacitance to ground of up to 1.7-2.5 μ F. When subjected to power frequency withstand voltage, the capacitance current reaches 25-35A, and the test equipment has a capacity of thousands of kVA. When using conventional test equipment, the equipment is cumbersome. More seriously, when using conventional high-capacity testing equipment, the short-circuit current at the fault point when the insulation of the generator stator winding is broken down is high, which can burn out the iron core and cause significant economic losses. According to the provisions of section 6.2.1.1 of the national standard GB/T16927.2-1997 "High voltage testing techniques", the test voltage should generally be an AC voltage with a frequency of 45-65Hz, commonly referred to as the power frequency test voltage.
In order to meet the requirement that the voltage frequency of the AC withstand voltage test of the generator is the power frequency, the series resonance device of the generator is usually of the induction type. By adjusting the air gap of the iron core to change the inductance, the purpose of power frequency resonance is achieved.

Our Factory

Beijing Huazheng Technology Co., Ltd. was established in 2023, headquartered in Beijing, China. It is an enterprise with outstanding innovation capabilities in the field of high voltage testing equipment. Our mission is to provide customers with high-quality and efficient solutions, with the goal of promoting social progress and sustainable development. Our values are integrity, innovation, and collaboration, always putting customers first. Our strengths lie in our technical strength, quality control, customer service, and partnership. We have a professional R&D team and advanced production equipment, which can provide innovative solutions and high-quality products. We strictly adhere to the international quality management system, ensuring the stability and reliability of our products and services. We have established a comprehensive pre-sales, sales, and after-sales service system to provide customers with comprehensive support and solutions. The long-term cooperative relationship established with well-known domestic and foreign enterprises has further promoted the development of the industry. We will continue to uphold the concepts of integrity, innovation, and excellence, and contribute more to the development of the high voltage test equipment . Choose Beijing Huazheng Technology Co., Ltd., choose trust and success.

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Asked Questions

Q: What is an AC resonant test equipment?

A: The AC resonant test equipment generates a continuous variable AC voltage for testing the HV capacitive object. Capacitive test object includes cables, capacitors, GIS, generator set, capacitive instrument transformer, etc. The variable inductance resonant test system can be used at 50Hz and 60Hz or even higher frequency.

Q: What does an AC resonant test equipment behave as?

A: Explanation: At resonance, inductive reactance is equal to capacitance reactance. At this condition, circuit acts as purely resistive.

Q: What is resonance in an AC circuit?

A: Resonance is the phenomenon in the electrical circuit, where the output of the electrical circuit is maximum at one particular frequency. That particular frequency is known as the resonant frequency. At the resonant frequency, the capacitive reactance and inductive reactance are equal.

Q: What is meant by resonant AC?

A: Resonance in an AC circuit refers to that state of the circuit in which the inductive reactance of the circuit is equal to its capacitive reactance.

Q: What is the resonant frequency of AC resonant test equipment?

A: At the resonant frequency of an alternating current circuit, the impedance of the circuit equals the resistance of the circuit. The resonant frequency, 𝑓 , of an alternating current circuit is given by 2 𝜋 𝑓 =  1 𝐿 𝐶 , where 𝐿 is the inductance of the circuit and 𝐶 is the capacitance of the circuit.

Q: What is the application of resonance in AC circuits?

A: One use for resonance is to establish a condition of stable frequency in circuits designed to produce AC signals. Usually, a parallel (tank) circuit is used for this purpose, with the capacitor and inductor directly connected together, exchanging energy between each other.

Q: Under what condition is an AC circuit said to be resonant?

A: The circuit is said to be in resonance if the current is in phase with the applied voltage and not if the current is out of phase with the applied voltage. The study of resonance is very useful particularly in the area of communications.

Q: What is the sharpness of resonance in an AC circuit?

A: What is the sharpness of resonance? The sharpness of resonance is defined using the Q factor which explains how fast energy decay in an oscillating system is. The sharpness of resonance depends upon: Damping: Effect due to which there is a reduction in amplitude of vibrations.

Q: How does a resonant circuit work?

A: A resonant circuit is formed when a capacitor and inductor (coil) are in parallel or in series. The two circuit elements will block or pass a single specific frequency out of a divers mix. For this reason, resonant circuits make possible radio and TV transmission and reception and perform many other useful tasks.

Q: What is the power factor of an AC circuit at resonance?

A: Therefore, the power factor of an LCR circuit at resonance is 1. Note: At resonance, the LCR circuit behaves like a purely resistive circuit and the effects of the capacitor and inductor cancel each other out. This is the most efficient circuit for operation.

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