6 Latest Developments in Electrical Insulation Systems for Generators and Transformers High-voltage equipment for power generation and transmission systems is continuing to evolve to reduce production costs and increase efficiency. Recently, it is also required to minimize the impact on the environment. In these devices, the most important performance is insulation. In order for the insulation system to operate safely and reliably, the performance manufacturing process and insulation structure of the insulation material are the most important. In order to make the insulation system operate safely and reliably, the performance manufacturing process and insulation structure of the insulating material are the most important. A series of changes have occurred in high voltage insulation systems over the past few decades. The application of 3 corpse 6 led to the development of 56 circuit breakers 013 and 01 Ding, etc. Excellent insulation performance and advanced technology enable it to be applied to high voltage cable insulators and other high voltage equipment. Recently, the existing technology has been applied to a new field. The high-voltage cable technology used for transmission and distribution has been used as a high-voltage winding in generators and transformers, resulting in a new type of high-voltage generator. The wind power system was also identified by the 0,1 and oil-free power transformer DryfonerTM. Recent developments in transformer insulation systems have focused specifically on the comparison between insulation and insulation properties of conventional and new equipment. In the original cable, air was mainly used with natural rubber eucommia gum and paraffin wax rosin and asphalt, and later impregnated with mineral oil. As higher and higher voltages are required, oil-filled cables have been developed to prevent partial discharges in the voids. Today, two major power-electric liquid-impregnated paper cables and extruded polymer cables are mainly used in power transmission and distribution systems. Extrusion cable insulation starts with thermoplastic polyethylene and is quickly replaced by chemically cross-linked polyethylene. This has occupied the entire industry and is now commonly used in underground distribution systems. Due to major advances in this technology, it has quickly turned to transformer applications. field. Today, the main components of power cables are the series of changes in the high-voltage insulation system that have two layers of semiconducting layers inside and outside the conductor over the past few years. Insulation materials have been improved to increase the electric field strength they are subjected to. For example, rotary electric power cable technology has a long history of power cable technology. Since the widespread use of incandescent lighting systems in the 1880s, it has begun to be formed in the early 20th century. The conductor is made of a plurality of strands of copper or aluminum wire, and then the conductor is covered with an insulating material, and finally a metal sheath is applied to the insulation. New applications for cable technology have increased by a factor of two. Good electrical insulation using insulated cables for underground electrification has been introduced, for example, facilities. 0,06, this is a company with a wealthy company, or is acquired by a group or company with economic strength to form a new power electronics company, so that enterprises can obtain new development opportunities. Some enterprises actively undertake national key projects or military projects, obtain state funding and low-interest loans, and enterprises have achieved rapid development. 3 Product quality is the key to whether the product can enter the international market. At present, there is still a certain gap between the quality of China's power electronics products and the quality of foreign large companies. We must make great efforts to improve product quality and meet international standards in order to be invincible in the fierce international market competition. Since January 1987, we have been working with domestic companies to discuss the export of power electronics in China with US users. Now, Sencheng has been exploring for 15 years. In the future, Sencheng will strengthen cooperation with domestic enterprises to jointly develop the overseas market of China's power electronic devices. We firmly believe that in the era of Houding 0, there will be space for the development of China's power electronics companies in the same market and in the world. At that time, overseas institutions and sales agents of China's power electronics companies will be spread all over the world. Huifu's operating experience is traditionally 1 cable insulation system, but does not require metal shielding and sheathing. In this application, the high voltage cable winding consists of a semiconducting layer of solid dielectric and an outer semiconducting layer in the conductor, which is commonly referred to as a cable core in conventional cable terminology. The material and processing of the cable is in phase with that used in high cable technology. In this way, it is virtually identical to the cable normally used in power transmission and distribution systems. In the case of cable systems, cable assemblies and terminations are also required for new applications, as cable and cable accessories control the cable winding system as the best choice. However, adapters are always used between cables of different insulation sizes, and the joints vary from case to case. Applying this high-voltage cable technology to generators and transformers is at the heart of the new insulation concept, and it gives this device new possibilities for improved operational performance. In conventional generators, the stator windings consist of square insulated conductor bars. In the past 20 years, although the working voltage to the ground has increased, the changes in insulation materials and systems are relatively small. For generators that use mica tape outside the conductor and then impregnated with epoxy or polyester resin, today's field strength is 2.510. For insulation systems using mica tape, it is very important in the manufacturing process. Keep the insulation system free of voids, but mechanical stresses and thermal cycling can cause void formation. Therefore, as the voltage increases, partial discharge must occur in the insulation. The beginning of the conventional stator bar is uneven in shape and the electric field strength at the corner is high. In addition, in the winding end region, complex measures must be taken to control the electric field strength to avoid partial discharge and corona. The design principle of the traditional generator makes the output voltage not exceed 3035, and the voltage of the electric power transmission has reached 800 or even higher. The conventional generator-based power plant often needs a step-up transformer. Contrary to the traditional generator, the winding of 0. 60161 is composed of extruded and 1 cable, which can avoid the electric field non-uniformity of the traditional insulation structure. The cable winding is a cylindrical conductor with a uniform electric field distribution along the conductor surface, and the stator slot can be shaped to fit the cable winding with shield insulation. Today, this application, insulated field strength can reach 15, and the existing 500, cable facilities can achieve. Therefore, the new generator provides a high-voltage generator that can directly connect to the transmission system voltage standard without a step-up transformer, and also reduces the power loss and improves the separation of the effective mechanical stress and the magnetic stress. These basic design parameters can be selected independently and optimally so that the materials associated with them can be improved. In the spring of 1998, the prototypes of the 45 and 6001 generators were put into operation in northern Sweden. Another generator is either running or under construction. They are turbine generators with rated capacities of 136 to 42 centimetres and 3000, 1 and hydroelectric generators with 155 let, 75 MW and 125 rm. Based on the evaluation of the 6-player 001 technology, the wind farms located in the offshore and coastal areas have recently developed a new type of wind power generation system with a typical power rating of 35 PCT. The boundary design is also the basic design feature of the high voltage cable winding of the stator. The basic principle is that the rotor is a permanent magnet, the rotor is directly coupled with the turbine without a gearbox, and the DC collector system. The design of the company is optimized in terms of electrical circuits. For example, two rows of cable windings are installed in each stator slot, and each phase says that no cable connectors are required. Typically, WindfomerTM is installed at sea or near the coast. Therefore, all materials used in the boundary printing should be carefully selected to prevent rusting of the metal parts and aging of the dielectric under severe environmental conditions. In conventional power transformers, the insulation system consists mainly of mineral oil and cellulose paper, which has proven to have outstanding dielectric and thermal properties. From the point of view of the insulation system, this is a very effective combination. The dielectric strength of the paper and the oil itself reaches 40 and 12, respectively, and the dielectric strength of the combination is 64 claws. However, for transformers, for a variety of reasons, their field strength is only 1.5, claws. There are also inadequacies in oil-paper insulation, such as the danger of fire and splashing of dangerous oil. The oil-paper insulation system of the traditional transformer can obtain good dielectric performance only after a very thorough treatment process. In the natural state, paper or paperboard typically contains 510 moisture, so the first step is a high temperature process up to 130, and a complete drying process under vacuum to reduce the moisture content to about 5, the first step is to work Component core. The winding blocks and leads are vacuum impregnated so that the mineral oil reaches and fills all voids in the insulation system. It is completely dry and it takes about two weeks. Therefore, technology developers have great interest in the dry design of power transformers. The two existing types are insulated three gas transformers and transformers made of molded epoxy fiberglass materials. The voltage level of the gas-insulated transformer can reach 275. With the improvement of environmental protection requirements, people hope to find a substitute for the species 3. The transformer with molded epoxy fiberglass insulation has a maximum voltage rating of only about 36kV, mainly because the internal field strength exceeds the partial discharge starting voltage. Because the newly introduced dry-type transformers 0,1 contain neither oil nor paper, there is no danger associated with flammable oils, and no expensive complete drying process is required. The difference between the traditional transformer and the 1 is not only in the insulating material but also in the insulating structure. For a conventional power transformer, the insulation system consists of two parts: 4 insulation and turn-to-turn insulation. The main insulation is that the winding and the grounding component must not only withstand transient overvoltages caused by lightning and circuit breakers, but must also withstand AC stress. For turn-to-turn insulation, the design requirements are primarily the effect of transient overvoltage. The electric field analysis of the turn-to-turn insulation model shows that the electric field strength is greatly increased in the oil gap between the winding edges. For cable windings, 7171 does not have such a problem, because the outer semi-conductive layer is grounded, and the insulation of the cable winding only needs to function as the main insulation in the conventional transformer. In addition, the combination of high-voltage cable technology and transformer technology can present the mechanical strength and heat-resistance limit of the dielectric strength windings of the insulation system in various transformers. In the new technology, different functions can be independently performed. To the best condition. 17,10 single-phase transformers, the main purpose of the construction is the concept of performance and verification design ideas. The first station is to find 1 Sweden in the 6th hydropower station for the outing of 3 Yang. The first station has also been installed. The general characteristics of the voltage drop of the cable are important. The contact resistance of the outer surface of the cable surface is important. The resistivity of the outer conductive layer must be too high in a certain range, causing the potential between the two contact points of the semiconductive layer to be too high, and the resistivity is too low, resulting in an increase in power loss in the semiconductive layer. It is also important to maintain good contact between the semiconducting layer and the grounding system. Winding For a new type of generator and transformer-connected cable winding, the electric field strength gradually decreases along the linear end of the cable winding to the neutral point under AC voltage. Therefore, in order to minimize the amount of insulation used, the cable winding can be composed of several high-voltage cables of different insulation thicknesses. The distribution of the impulse voltage along the winding is different from that under the AC voltage. The insulation strength of the segment cable must be able to withstand the transient overvoltage applied to the end. The insulation thickness must also be considered. Work field strength should pay attention to the cable technology insulation design. Today's cable insulation and production techniques such as dry cross-linking. Ultra-clean production and re-extrusion can produce reliable cables with a working field strength of more than 15,1. In the insulation design of new generators and transformers, the field strength is currently controlled at around 10,1, which is selected according to the actual situation within the voltage range under consideration. In the future, higher electric field strength will be introduced. Such high electric field strength is impossible to achieve electric field distribution for conventional oil insulation based on mica and epoxy, so the insulation of the cable is fully utilized. Mechanically, in order to avoid the abrasion of the outer semi-conductive layer caused by vibration, the gap between the cable and the groove wall is inserted into the silicone rubber corner band, so that the cable winding is firmly fixed in the groove. The fixing force provided by the silicone rubber gasket can also accommodate the thermal expansion of the cable insulation, while also keeping the outer semiconducting layer in good contact with the grounded stator core. The evaluation 60 has its own characteristics in the groove design and winding method, in which there are two rows of cable windings in each slot, so different methods are used to fix the cable in the slot. The resistivity of the outer semi-conductive layer of the 0016 cable winding is currently about 40. The high-voltage generator developed by the large wind turbine 188 company of the transformer can be directly connected to the grid. Wen Lilian is the control plane potential, and there is a point on the outer side of the cable winding. AC grounding. In terms of heat, the current in the 6-station stator winding cable is very small, so the ratio of ohmic loss to iron loss is much lower than that of the conventional generator. Most of the heat is generated by the fixed core at the ground potential. The cooling system is greatly simplified. A water cooling circuit is installed in the 6 016 stator cores to maintain the system at an acceptable temperature. In conventional transformers, oil is used both as insulation and as a cooling medium, so there is a non-segmental relationship between the two functions. However, for 0 ice and claw 1, the relationship between dielectric insulation and cooling is extremely small, and the air cooling or water cooling system can be optimally selected as long as the operating temperature is kept within the specified value. Conclusion Mica epoxy and oil cellulose paper have dominated the insulation systems of rotating electrical machines and power transformers for many years. However, in recent years, cables have been introduced into generators and transformers as high-voltage windings, which has led to the emergence of new generators, 016 wide, new wind power systems, and new transformers. The new high-voltage generators and transformers have the characteristics of high efficiency and low environmental impact, which gives new possibilities for high-voltage equipment design. The products introduced represent the possibility of high-voltage electromagnetics.茗 Recently, the Swiss Six 88 company successfully developed a low-speed, high-voltage and large-capacity wind turbine that does not require gearbox speed-up and does not require transformer boosting, thus bringing about a revolution in the history of motor development in the past 100 years. It is not limited to the wind power field, and will be widely used in water turbines and steam turbine generators, saving a lot of transformers. Different from the traditional wind turbines, this new wind turbine, called the boundary 10, 1 passes through the gearbox, using a large-diameter disc-type permanent magnet steel rotor instead of an asynchronous generator rotor. The stator windings use a circular high-voltage cable. Instead of a rectangular cross section of copper wire. This round high-voltage cable technology is a patented invention of the Swiss company 88. All stator windings are wound by a root cable with no joints in the middle and high reliability. The generator voltage can reach more than 20, up to 400. The initial power generation frequency is about 5, and after passing through the pole tube rectifier and the thyristor inverter, 50 2 power frequency AC powers are obtained. The new wind turbine has a stand-alone capacity of 3,5 PCT. When the capacity is 3 circles, the center height of the wind turbine is 70, 3 blades, and each blade is about 45 long made of epoxy glass reinforced plastic. The large-diameter disc-type permanent magnet steel rotor with multi-pole structure has a diameter of more than 6m and a rotational speed of about 18r min. In order to adapt to offshore operation, the permanent magnet steel adopts anti-corrosion material. The unit can be operated at a variable wind speed of 528 meggars, and the rated speed is reached at a wind speed of 13,18. Below the rated wind speed, the blade angle is automatically adjusted to the effective position; when the wind speed is 18, 27 claws 5, the output power is reduced from 34 to 500. When the wind speed averages 8 to 3, the annual power generation is about, bound. Since the gearbox transformer and the power factor calibrator are omitted, the cost of the new unit is greatly reduced, and the operation and maintenance costs are reduced, the efficiency is improved, and the availability is improved. And after the unit's service life, the effective materials can be recycled. The use of permanent magnet steel for the rotor is also good for the environment. Due to the extensive use of environmentally friendly materials, the characteristics of this unit are conducive to the ecological environment. The basis for the development of this new type of wind turbine is the 0-six-and-a-zero-to-one technology, which means that a high-voltage generator system that can be directly connected to the grid without using a step-up transformer, that is, a circular high-voltage cable patented invention. In addition to the first large-capacity wind turbines on the Swedish Nassudderr offshore wind farm to be commissioned, this new technology was first applied to generators installed on the Polis hydroelectric power station on the Luray River in northern Sweden in May 1998. It can be directly connected to the grid without a transformer. The EskUstuna 54kV high-pressure turbine generator, which is scheduled to be operational by the end of 2000, will be a milestone in the application of this new technology for high-voltage generators. In addition to the above-mentioned new wind power, hydropower and thermal power products, this new technology can also be used for technological transformation of old products. Therefore, this can increase output power by 20, reduce maintenance costs by half, and the focus of the power generation equipment industry, which has caused a sensation in recent international power grid conferences. Follow Single Screw Extruder can process all kind of plastics products with auxiliary machines concerned, such as fim, pipe, stick, plate, thread, ribbon. Insulating layer of cable, hollow products and so on. It is also used in graining. Single Screw Extruder Single Screw Extruder,Plastic Single Screw Extruder,Hdpe Film Single Screw Extruder,Plastic Single Screw Extruder Suzhou Beakeland Machinery Co., Ltd. , http://www.beakelandpm.com
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