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China industrial electrical current situation and development trend

Release date:2013-07-09
Electrical disciplines and still is one of being prosperous science. As the national economy and national defense modernization, the rapid development of the electrical raised more and more requirements. Currently, the electrical structure and working principle continuous improvement and innovation, increasingly diverse varieties and specifications is one of its characteristics. So what appliances? Those who live for electrical appliances can be referred to. 

At a voltage level, the highest operating voltage has been developed to 765kv and above, and 1500kv EHV electrical equipment prototype has also been developed, the minimum voltage reaches a few volts or less. 

At current levels, the maximum operating current of tens of thousands of amperes or more, while the minimum operating current of milliamps or smaller electrical equipment or components. 

In the power frequency, the well-known dc and 50 Hz or 60 Hz frequency AC power is still widely used. In addition, low-frequency, ultra-low, medium, high and ultra-high frequency pulse power supply electrical components and devices have been developed and widely applied. 

Currently, electrical equipment or components from half a match structure size to the size of the development of up to several-storey giant did not prepare. On the rational organization of production and use of electrical appliances, scientific and rational division of the voltage and current levels, to minimize product specifications and models have practical significance. Try to develop "modular", "building blocks", "standard cell", as well as spare parts universal, high interchangeability appliances or components is very important. Especially in the current economic reform process, strengthen macro leadership and actively carry out scientific and technological disciplines, academic exchange activities is very important. In this way, can mobilize the various disciplines complement each other, learn from each other. 

2, high-voltage electrical  

high-voltage electrical transmission and distribution network development and road development are closely linked.Currently, 200 to 3,000,000 kw of power stations has occurred, from 1000 to 12 million kw large capacity power station is the inevitable trend of development, such as the Three Gorges water conservancy and other water conservancy and Southwest. However, there is a small river, the construction of small power stations are everywhere. For economic transmission power, to improve the working voltage transmission networks is an important methods. To this end, there will be a series of technical problems waiting for scientists to study electrical resolved. For example: 1) a variety of electrical voltage and current limits, the study of the economy and may limit the output capacity problems; 2) Overvoltage protection research, research the causes of over-voltage and harm, thereby using the corresponding limit, reduce or eliminate Overvoltage measure is very meaningful. For example, a transformer 500kv grade copper almost the same amount of weight with less insulation. Thus, the study measures to reduce the over-voltage insulation to reduce levels of practical significance. Currently there way to do * for the division limit overvoltage in the range of 1.5 to 2.0 times, 3) internal insulation free discharge, anti-aging research with dirty long air gap discharge characteristics of the outer insulation; 4) arc Off the new principles, new media research. For example, vacuum switches, sulfur hexafluoride, as well as to improve the conventional air up to 150 atm, and the like; 5) new principles, new Structure.For example, the capacitor voltage transformers, optical current transformer (magneto-optical effect type, the light pulse repetition frequency modulation type, etc.). 

In addition, due to the high voltage, high current thyristors successfully developed, to the development of HVDC network provided the conditions. This paper proposes a switching DC transmission network switches and electrical equipment requirements. At present, China has adopted 22kv electrified railway line above the level of the DC power supply system, in Shanghai, Xi'an and other places have been pilot voltage 500kv line. Overall, in the country to run from the test pattern type phase. Many scientists in the theory and technology, there have been new progress. Foreign countries have 1000kv or so ultra HVDC network running. This system for ultra-distance transmission of economic value is relatively large. 

High and low voltage electrical switches * for institutional flexibility and may * also a very interesting research topic. 
Short-circuit fault automatically disconnect and then automatically switch the automatic reclosing device is also very practical value and economic issue. Sulfur hexafluoride switch with compressed air and vacuum leak-proof and maintenance is an important issue to be solved. Oil circuit breaker is still applied. 
3, low-voltage electrical  

appliances are low-power and low-voltage electric main electrical equipment. In most cases, installed in the control panel (or cabinet) in the use of electrical equipment made. Individual cases are also used alone electrical (or components). Low-voltage switchgear low-voltage electrical field is one of the main products. Now, the key technical problems and improve life problems can be *. This has received some attention at home and abroad. It involves the electromagnetic structure and theory, agency theory, technology and materials technology, as well as some parts of the movement (for example, spring, short-circuit ring, contacts, etc.) resistance to shock and vibration and abrasion resistance. For example, the current of the electromagnetic switch AC short-circuit ring is made ​​to improve the life of built-in an effective way. 

Now began to use a new type of civil automatic switch instead of the traditional knife switch - fuse with the use of the program, especially in the frequent occurrence of an overload or short-circuit fault when used on a building cost is relatively large. Although a slightly higher investment, but can improve the quality of power supply, and can save a lot of fuses, meanwhile, fault recovery may be *. Therefore, research and development of low-voltage electrical and promote the application is very important. 

Semiconductor and silicon and other new components appear to combine with electromagnetic devices can be made ​​with a variety of functional automation equipment, they will be in the national economy, national defense, and life has been widely used in the field. For example, the various uses frequency power supply device instead of stationary rotary motor (already made ​​hundreds of watts to tens of thousands of kilowatts of device), magnetic semiconductor electronics, semiconductor switches, magnetic semiconductors adjustment and stabilization devices. In order to comprehensively solve the technical problems that often require the development of "composite", "building block" or standard units and parts commonality of other electrical equipment. This is the current need or have strong research and development of new trends. 

Low-voltage electrical appliances is another aspect of the new technology to open up the field. In appearance, suitable, no noise, safety, energy saving, excellent function, easy maintenance and other technical indicators should try to meet before the market is highly competitive, and access to foreign markets, by the thousands of families Welcome. 

Since large-scale and medium-scale integrated circuits, etc. The successful development of microcomputers and electronic appliances in many respects has been widely used. This gives appliances, instruments and instrument miniaturization has brought great impact. Thus, it has developed a number of weak electrical appliances, electrical and instrumentation and instrumentation micro samples. 

Nevertheless, the current domestic and international magazine introduces basic electrical theory, the addition of the electromagnet of articles up. Magnetic amplifier applications have been improved, especially in the primary and secondary electrical isolation requirements and high-precision measurement and control aspects of semiconductors and other devices can not match. Electromagnet gap permeance gδ = f (δ) and derivative dg8/ds accurate calculation method, arc theoretical and computational methods have been fully resolved. Currently Rengyi * empirical data or formulas approximate calculation. Finally Rengyi * trial to resolve. 

4, electrical materials,  

electrical materials include insulating materials, conductive materials, magnetic materials, and semiconductor materials, and several major aspects. 

Insulating materials at high temperature, pressure, infrared radiation, ultra-low temperature synthesis of new materials such as body has gradually been developed. Thus, the temperature reached 200 ℃ enameled wire has been widely used, and high temperature magnet wire 250 ℃ also have been developed. Aluminum and copper to the research work in some electrical equipment has been applied. 

Currently there are a number of new varieties of magnetic materials, high-quality low-coercive magnetic steel sheet can be rolled into a thickness of 0.1mm, having a high coercive force of the permanent magnet materials, such as br = 12000gs, hc = 3000oe, and br = 6000gs , hc = 6000oe magnetic ceramics have been developed. 

In addition, the thermal core, magnetic bubble, the use of magnetic single crystal made ​​of filter components. High permeability magnetic material high resistance and high strength are also developing the research process. 
Semiconductor materials manufacturing process of continuous improvement, transistors, thyristors, turn-off thyristor, triac element, thermal, magnetic, gas, force sensitive, photosensitive semiconductor devices and other special have been developed. , The LSI, etc. can be subtly realize various control logic functions, so that the production process automation easier to implement.
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