The variable frequency series resonance test system is a high-voltage electrical equipment insulation performance detection device designed based on the principle of series resonance. It is widely used in industries such as electricity, metallurgy, petroleum, and chemical engineering, and is suitable for AC voltage withstand tests of large-capacity, high-voltage capacitive test samples, such as insulation performance detection of high-voltage cross-linked cables, generators, GIS (Gas Insulated Switchgear), transformers, and other equipment.
1. System composition
The variable-frequency series resonance test system primarily consists of the following core components:
Variable frequency power supply
Convert the mains frequency power supply (220V/380V, 50Hz) into a sine wave output with adjustable frequency (typically ranging from 20-300Hz), while integrating operation, protection, control, and monitoring functions into one.
Imported power components or intelligent power modules (IPM) are used to ensure the stability of voltage and frequency output.
② Excitation transformer
The voltage output by the variable-frequency power supply is boosted to the required level for testing, while the high-voltage and low-voltage parts are isolated to ensure operational safety.
③ High-voltage reactor
Form a series resonant circuit with the test capacitor, and adjust the frequency to make the circuit reach a resonant state, thereby generating high voltage.
④ Capacitive voltage divider
It is connected in parallel to the test object, used to measure the resonant voltage, and provides an overvoltage protection signal.
2. Working principle
The system is based on the LC series resonance principle. By adjusting the output frequency of the variable-frequency power supply, it ensures that the loop inductance (L) and the capacitance of the tested object (C) meet the resonance condition: f= 1/2π LC
When the test frequency equals the resonant frequency, resonance occurs in the circuit, and the voltage on the tested object is Q times the output voltage of the high-voltage terminal of the excitation transformer (Q is the system quality factor, usually ranging from tens to over a hundred). Through the resonance effect, the variable-frequency power supply only needs to output a relatively small voltage to generate a high test voltage on the tested object, significantly reducing the requirement for power supply capacity.
3. Technical Features
① Small size and light weight
The weight and volume of the equipment are only 1/10 to 1/30 of traditional power frequency voltage withstand devices, making it easy to handle on site and flexibly configure.
② The automatic tuning function is powerful
The system supports automatic frequency scanning from 30Hz to 300Hz, displaying the frequency scanning curve, allowing users to intuitively observe the tuning process.
After the frequency sweeping is completed, the system performs a fine sweep within a range of ±5Hz around the resonant frequency point, with a resolution of 0.01Hz, to precisely lock onto the resonant frequency.
③ Multiple testing modes
Supports modes such as "Automatic tuning + Manual voltage adjustment", "Automatic tuning + Automatic voltage adjustment", and "Manual tuning + Manual voltage adjustment".
It is recommended to use the "automatic tuning + manual voltage regulation" mode, which takes into account both efficiency and safety.
④ User-friendly human-computer interaction
Operated via a full touch screen, it allows for the setting, control, and display of test parameters and results on the same screen. It also features automatic timing and operation prompts.
Supports the saving and querying of experimental data, with the capability to store up to 200 test records.
⑤ Complete protection function
Zero position protection (start-up is prohibited when the voltage output control knob is not at the zero position), overvoltage protection, overcurrent protection, flashover protection, etc.
The action response time can reach up to 1 microsecond, ensuring the safety of the experiment.
4. Application scenarios
① High-voltage cross-linked cable
Suitable for AC voltage withstand test of cables with voltage levels ranging from 6kV to 500kV.
② Generator
Support power frequency voltage withstand test for generators of 600MW and below.
③ GIS and SF6 switches
It is suitable for AC voltage withstand tests of 110kV-500kV GIS equipment and SF6 switches.
④ Transformer and motor
Used for power frequency voltage withstand test of transformers and motors of 110kV and below.
⑤ Other electrical equipment
Including insulation performance testing of capacitive test samples such as busbars, bushings, and transformers.
ZCVF-A series frequency conversion series resonant AC withstand voltage device 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.
Kvtester Electronics Technology Co.,Ltd. is a high-tech enterprise specializing in power testing, testing, research and development, production, and sales of testing equipment. It has been engaged in the electrical testing industry for many years, and its products are of high quality. We welcome customers to come and purchase. Service hotline: 0086-27-81778799, to learn more, visit the official website: www.kvtester.com
