What are the classification of transformers and what are the fault detection technologies for transformers
A transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. The main components are the primary coil, the secondary coil and the iron core (magnetic core). The main functions are: voltage transformation, current transformation, impedance transformation, isolation, voltage regulation (magnetic saturation transformer), etc. So, what are the classifications of transformers? What are the fault detection technologies for transformers?
What are the classifications of transformers
At present, the representative products that have been operating in the system include: 1150KV, 1200MV·A, 735~765KV, 800MV·A, 400~500KV, 3-phase 750MV·A or single-phase 550MV·A, 220KV, 3-phase 1300MV·A power Transformer; DC transmission ±500KV, 400MV·A converter transformer. Power transformers are mainly oil-immersed, and the product structure is two types: core type and shell type. The core-type production accounts for 95%, and the shell-type only accounts for 5%. There is no overwhelming advantage between the core type and the shell type, but the core type process is relatively simple, so it is used by most enterprises; while the shell type structure and process are more complicated, only traditional factories use it. The shell type is especially suitable for high voltage and large capacity. It has advantages in insulation, machinery and heat dissipation, and is suitable for the transportation of hydropower stations in mountainous areas.
The capacity of foreign distribution transformers can reach 2500KV·A, and there are circular and elliptical core forms. The circular ones are the vast majority, and the elliptical ones are elliptical because of the small M0 (spacing of the core column), so the material used can be reduced. Low-voltage coils are wired and foil, and fuel tanks are available with radiator pipes (a few) and corrugated (most).
Recently, dry-type transformers have developed rapidly in China. In big cities such as Beijing, Shanghai and Shenzhen, dry-type transformers have accounted for 50%, and in other large and medium-sized cities, it has also accounted for 20%. Dry change has four structures: epoxy resin casting, filler casting, wrapping and dipping. At present, open-ventilated H-class dry-type transformers are widely used in Europe and the United States. It is a new type of H-class dry-type transformer developed after absorbing the characteristics of the wrapping structure on the basis of the immersion type and using Nomex paper. Due to the high price, it is widely used in my country. Not yet promoted. At present, the dry-type distribution transformers with the largest short-circuit test capacity in China are 2500KV·A, 10/0.4KV; the dry-type power transformers with the largest short-circuit test capacity are 16000KV·A, 35/10KV. [2]
(4) Amorphous alloy transformer
Although the amorphous alloy transformer has poor short-circuit resistance and high noise, it is energy-saving, so the future development prospects are considerable. At present, China's largest amorphous alloy transformer iron core manufacturer has an annual iron core production capacity of 3000-4000t. The production technology of iron cores and transformers is not the key factor restricting the promotion of amorphous alloy iron core gold transformers. The breakthrough of amorphous alloy strips In order to promote the leap in product quality.
(5) wound core transformer
At present, the production of wound core transformers is mainly concentrated in the 10KV level, and the capacity is generally less than 800KV·A, and 1600KV·A has also been trial-produced, but the power sector purchases most of them with a capacity below 315KV·A, which is suitable for use in rural power grids. There are more than 200 wound iron core transformer manufacturers in China, 20% of which are of a certain scale. The production capacity of strong wound iron core transformers in China is about 16 million KV·A, but the actual output is relatively low.
What are the fault detection technologies for transformers?
(1) Online monitoring technology
The online monitoring technology mainly uses the vibration analysis method and the partial discharge detection method. One is the vibration analysis method. This analysis method refers to monitoring the strength of the vibration signal of the transformer when the transformer is running, and analyzing and summarizing the reasons for such monitoring results, so as to conduct real-time detection of the operating status of the transformer, which is conducive to timely detection of faults. Small failures are resolved before they become major failures. The second is the partial discharge detection method. This detection method refers to the internal failure of the transformer during operation, which in turn causes partial discharge, which will affect the level and speed of discharge. Therefore, it is necessary to strengthen the daily and effective judgment according to the partial discharge of the transformer, to detect whether there are hidden dangers of the transformer, and to solve these problems in a targeted manner to ensure the safe and stable operation of the machinery.
(2) Gas chromatograph technology
Gas chromatograph technology is mainly used to analyze the internal components of mixed gases. The advantages of this detection technology are mainly effective in the following aspects: high efficiency, convenient use, convenient operation and many other aspects, these advantages have promoted the technology to be widely used, and have been widely used in the field of detection of various electrical equipment. Applications. Among them, this technology is effectively used for the polymer membrane technology, which effectively and quickly decomposes oil and gas, and dissolves the oil under the action of the polymer and the influence of the transformer, which can effectively improve the fault gas and The concentration of gas in the oil. In most cases, when the transformer fails, it may emit the smell of hydrogen gas. Using this chemical characteristic can better detect the gas content and effectively detect the hydrogen in the fault gas of the transformer. In addition, the transformer is used to detect various gases, which greatly improves the diffusion speed of the faulty gas of the transformer, which is conducive to the timely recovery of the normal operation state.
(3) Sensor array technology
For the sensor array technology, the technology also plays a very important role in the transformer fault detection technology. For this reason, electric power inspection and maintenance workers need to master this technology proficiently, and apply this technology to the work of detecting faults scientifically and reasonably, which can effectively improve the safe operation index of the transformer, so that the operation state is not disturbed by the outside world. And because this sensor has the following advantages: high selectivity and high sensitivity, the sensor is used for online detection, thereby improving the speed of detecting the concentration of the faulty gas, which is beneficial to the detection of the content. It can be seen that it can not only improve the speed of detection, but also It can also improve the level of transformer fault detection technology and reduce the probability of occurrence of transformer fault detection.
(4) Infrared spectroscopy technology
Infrared spectroscopy technology is also known as infrared spectroscopy online detection technology. This technology has the advantages of fast detection speed, high accuracy, high sensitivity, and less maintenance. This technology also plays an important role in transformer fault detection technology. Detection of gas content due to transformer failure. In the actual detection work and in the specific use process, the infrared gas analysis instrument and the double-circuit film capacitance detection instrument can be effectively used for quantitative analysis.
