【武汉华天】Variable frequency series resonance

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Variable frequency series resonance is an AC withstand voltage test method used for different electrical equipment, and its detailed explanation is as follows:
1、 Basic principles
The variable frequency series resonance test device applies the principle of series resonance and uses an excitation transformer to excite the series resonance circuit. By adjusting the output frequency of the variable frequency controller, the circuit inductance L and the test sample C are connected in series resonance, and the voltage on the test sample at this time is the resonance voltage. When the circuit frequency f=1/2 π√ LC, resonance occurs in the circuit, and the voltage on the test sample is Q times the output voltage of the excitation transformer high voltage end. Q is the system quality factor, that is, the voltage resonance multiple, which is generally tens to hundreds or more.
2、 Equipment composition
The frequency conversion series resonance test device mainly consists of an isolation transformer, a frequency and voltage regulation power supply, an excitation transformer, a reactor, and a capacitive voltage divider. The capacitor and reactor of the test sample form a series resonant connection, and the voltage divider is connected in parallel to the test sample to measure the resonant voltage on the test sample and provide an overvoltage protection signal. The frequency modulation power output is coupled to the series resonant circuit through an excitation transformer, providing excitation power for frequency conversion resonance.
3、 Application Fields
The frequency conversion series resonance test device is widely used in industries such as power, metallurgy, petroleum, and chemical engineering, and is suitable for the handover and preventive testing of high-capacity, high-voltage capacitive specimens. Specifically, it can be used for AC withstand voltage testing of the following electrical equipment:
Cross linked cable: suitable for AC withstand voltage testing of 6kV~500kV high-voltage cross-linked cables.
Transformer: Suitable for power frequency withstand voltage test of 6kV~500kV transformers.
Generator: Suitable for AC withstand voltage testing of various large power generators, such as steam turbines and hydro generators.
GIS and SF6 switches: Suitable for AC withstand voltage testing of GIS and SF6 switches.
Other equipment: Suitable for AC withstand voltage testing of other high-voltage power equipment such as busbars, bushings, and transformers.
4、 Technical features
Reliable quality: The equipment has passed strict type testing and identification by national authoritative departments, ensuring reliable quality and ensuring the safety of testing personnel, test subjects, and the testing equipment itself.
Compact size: The device has a small size and light weight, making it very suitable for on-site use and transportation.
Low requirements for power supply: The requirements for on-site power supply are relatively low, making it convenient for practical applications.
Good experimental equivalence: able to simulate the voltage and current conditions under actual working conditions very well.
Low harmonic patented technology: The measured harmonic content is less than 0.3%, far below the national standard requirement of no more than 5%, greatly protecting equipment such as main transformers and generators from high-voltage harmonic damage.
Complete monitoring function: meets national standard requirements, has peak monitoring function, and can monitor test waveforms in real time.
Easy to operate: One click mouse style knob for "foolproof" operation, large screen LCD display, easy to use operation.
Comprehensive protection: overvoltage, overcurrent, discharge, overheating, and zero start protection are comprehensive and reliable, with fast action time.
5、 Precautions
Reliable grounding: During the test, the grounding must be safe and reliable to ensure the safety of the testing personnel and the tested object.
Accurate selection: Select a suitable variable frequency series resonance test device based on the voltage level, capacitance, and other parameters of the test sample.
Operating standards: Operate according to the test procedures and specifications to avoid equipment damage or inaccurate test results caused by misoperation.
In summary, the variable frequency series resonance test device is an efficient and reliable AC withstand voltage test equipment for electrical equipment, with broad application prospects and important practical significance.