What are the applications of partial discharge detection methods in high voltage

Partial discharge detection methods have many applications in high voltage switchgear. The following GDZX introduces the following four applications to everyone.

First, the application of transient low voltage detection method

When the partial discharge phenomenon occurs in the high-voltage switchgear, the transient low-voltage detection method is used for effective detection, and the electromagnetic waves formed by the partial discharge are leaked from the inner surface of the high-voltage switchgear by the cavity or the gap existing on the metal casing. The electromagnetic wave is propagated outside the high-voltage switchgear, where the transient low voltage is formed in the grounded metal casing. When the amplitude is in the range of a few millivolts to a few volts, the time formed is very short, showing a few nanoseconds. When the power is changed, the electric field is induced, and the magnetic field and the electric field are mutually excited. When the high-voltage switchgear receives the influence of electromagnetic waves, the ground voltage will appear on the cabinet. For this TEV signal, the use of professional sensors to capture the characters, more clear and accurate detection and analysis of the partial discharge of the high-voltage switchgear, including the size and frequency of the discharge phenomenon.

Second, the application of AE detection method

After the power system has accumulated for a certain period of time, the high-voltage switchgear generates partial discharge. In this process, the AE detection method is used to detect the discharge of the high-voltage switchgear. Since the electric energy can be converted into light energy, sound energy, heat energy, etc., when the air gap is electrically broken down, the electric energy will be The breakdown moment is converted into heat energy, and the gas that is broken down exhibits an expansion change due to "thermal expansion and contraction", and then continues to diverge outward in the form of sound waves. After a period of time, the gas that is broken down will gradually shrink, and subsequent sound waves will appear. Ultrasonic testing allows the inspector to analyze and determine whether a high-voltage switchgear has a partial discharge by judging the nature of these sonic waves.

Third, the application of light and infrared detection methods

When the high-voltage switchgear produces a partial discharge phenomenon, the spectrum formed is basically distributed in the range of 3kA to 5kA, and the corresponding peak is closer to 4kA. Therefore, when the partial discharge detection is performed by the light and infrared detection method, the detecting person can enlarge the spectral signal by means of the photomultiplier tube, thereby achieving the effect of detecting the partial discharge condition. Due to the partial discharge phenomenon in the high voltage switchgear, a certain amount of heat will appear, causing the temperature of the area where the discharge occurs to rise. If an infrared detector is used for the detection method, the temperature difference generated by the temperature change can be captured to determine whether a partial discharge occurs in the high voltage switch cabinet. From an objective point of view, there are relatively many factors affecting the temperature difference. The function of the infrared detector is low, so the infrared detection is only used as an auxiliary detection method.

Fourth, the application of UHF detection method

A partial discharge condition is generated in the high voltage switchgear, and the UHF detection method is used to detect and judge whether or not the high voltage switchgear has a discharge phenomenon. When the duration and rise time of the discharge pulse are shortened, the corresponding frequency is broadened. Under the influence of the coaxial structure of the high-voltage switch device, the attenuation degree of the pulse signal itself does not change greatly, which is a partial discharge detection method for the high-voltage switchgear, so that it can play a role in the range of ultra-high-wave frequency. The electromagnetic wave signal is detected and is protected from corona and other factors. Compared with other detection methods, the UHF detection method has the advantages of effectively improving the signal-to-noise ratio in the detection system, and can also improve the detection accuracy of the high-voltage switchgear discharge phenomenon to a certain extent, and improve the partial discharge detection performance.

Various discharge detection methods are widely used in the partial discharge detection of high-voltage switchgear, and the operation failure of the switchgear is found in time to prevent accidents in advance. The partial discharge interference technology of the high-voltage switchgear also requires electric power workers to conduct in-depth research to timely judge and deal with the discharge phenomena that occur, so as to ensure and improve the safe, stable and reliable operation of the power system. As one of the power test equipment manufacturers, GDZX will do its best.