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Section 1 Introduction 第一节介绍The modern society depends on the electricity supply more heavily than ever before.现代社会比以往任何时候对电力供应的依赖更多。
It can not be imagined what the world should be if the electricity supply were interrupted all over the world. 如果中断了世界各地的电力供应，无法想像世界会变成什么样子Electric power systems (or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world. 电力系统（或电力能源系统），提供电力到现代社会，已成为产业界的不可缺少的组成部分。
The first complete electric power system (comprising a generator, cable, fuse, meter, and loads) was built by Thomas Edison –the historic Pearl Street Station in New York City which began operation in September 1882. 托马斯爱迪生建立了世界上第一个完整的电力系统（包括发电机，电缆，熔断器，计量，并加载）它就是位于纽约市具有历史意义的珍珠街的发电厂始于1882年9月运作。
This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius. The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system. 这是一个直流系统，由一个蒸汽发动机驱动的直流发电机其供电面积约1.5公里至59范围内的客户。
Semiconductor switches are very important and crucial components in power electronic systems.these switches are meant to be the substitutions of the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing. 在电力电子系统，中半导体开关是非常重要和关键部件。
半导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。
Switching losses开关损耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses. 电力电子转换器的功率损耗分为开关损耗和寄生损耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses of capacitors,the eddy and the hysteresis losses. 寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗the switching losses are significant and can be managed. 这个开关损耗是非常重要的,可以被处理。
they can be further divided into three components:(a)the on-state losses,(b)the off-state losses and the losses in the transition states. 他们可以分为三个部分: 通态损耗，断态损耗和转换过程中产生的损耗。
unit1 taxe A 电力变压器的结构和原理在许多能量转换系统中，变压器是一个不了缺少的原件。
它使得在经济的发电机所产生电能并以最经历的传输电压传输电能，同时对于特定的使用者合适的电压使用电能成为可能。
变压器同样广泛的应用于低功率低电流的电子电路和控制电路中，来执行像匹配电源组抗和负载以求得最大的传输效率。
隔离一个电路与另一个电路在两个电路之间隔离直流电而保证交流电继续通道的功能。
在本质上，变压器是一个由两个或多个绕组通过相互的磁通耦合而组成的，如果这其中的一个绕组，原边连接到交流电压源将产生交流磁通它的幅值决定于原边的电压所提供的电压频率及匝数。
感应磁通将与其他绕组交链，在副边中将感应出一个电压其幅值将取决于副边的匝数及感应磁通量和频率。
通过使原副边匝数比例适应，任何所期望的电压比例或转换比例都可以得到。
变压器工作的本质仅要求存在与两个绕组相交链的时变的感应磁通。
这样的作用也可以发生在通过空气耦合的两组绕组中，但用铁心或其他铁磁材料可以使绕组之间的耦合作用增强，因为一大部分磁通被限制在与两个绕组交链的高磁导率的路径中。
这种变压器通常被称作为心式变压器。
大部分变压器都是这种类型。
以下的讨论几乎全部围绕心事变压器。
为减少铁心中的涡流所产生的损耗，磁路通常由一叠薄的叠片所组成。
如图1.1所示两种常见的结构形式用示意图表示出来。
芯式变压器的绕组绕在两个矩形铁心柱上，壳式变压器的绕组绕在三个铁心柱中间的那个铁心柱上，。
0.14毫米厚的硅钢片通常被用于在低频率低于几百Hz下运行的变压器中，硅钢片具有价格低铁心损耗小，在高磁通密度下，磁导率高的理想性能，能用做高频率低能耗的标准的通讯电路中的小型变压器的铁心是由被称为铁氧体的粉末压缩制成的铁磁合金所构成的。
在这些结构中，大部分的磁通被限制在固定的铁心中与两个绕组相交链。
绕组也产生多余的磁通，像漏磁通，只经过一个绕组和另外的绕组不相交链。
虽然漏磁通只是所有磁通的一小部分，但它在决定变压器的运行情况中起着重要的作用。
电气工程及其自动化专业英语课后翻译The pony was revised in January 2021——电流之比才是恒定的，并且这个比值也取决于温度以及其它环境因素。
我们通常应当把线性电阻器仅仅称为电阻器。
只有当需要强调元件性质的时候才使用更长的形式称呼它。
而对于任何非线性电阻器我们应当始终这么称呼它，非线性电阻器不应当必然地被视为不需要的元件。
如果一个电路有两个或多个独立源，求出具体变量值（电流或电压）的一种方法是使用节点分析法或网孔分析法。
另一种方法是求出每个独立源对变量的作用然后把它们进行叠加。
而这种方法被称为叠加法。
叠加法原理表明线性电路某个元件两端的电压（或流过元件的电流）等于每个独立源单独作用时该元件两端的电压（或流过元件的电流）的代数和。
相电压与相电流之比等于电路的阻抗，符号为字母Z ，阻抗是一个具有量纲为欧姆的复数量。
阻抗不是一个相量，因此不能通过把它乘以 并取其实部把它转换成时域形式。
但是，我们把电感器看作是通过其电感量L 表现为时域形式而通过其阻抗jwL 表现为频域形式，电容在时域里为电容量C 而在频域里为 ，阻抗是某种程度上的频域变量而非时域变量。
无论是星型连接的电源还是三角形连接的电源都有重要的实际应用意义。
星型连接的电源用于长距离电力传输，此时电阻损耗(I2R)将达到最小。
这是由于星型连接的线电压是三角形连接的线电压的 倍，于是,对于相同的功率来说，三角型连接的线电流是星形连接的线电流的 倍。
三角形连接的电源使用在根据三相电源而需要的三个单相电路中。
这种从三相到单相的转变用在住宅布线中因为家用照明和设备使用单相电源。
三相电33源用在需要大功率的工业布线中。
在某些应用场合，无论负载是星形连接还是三角形连接并不重要。
模拟电子电路是关于其中电压和电流是对物理量进行模拟的且连续变化那些系统。
复制音乐的电子电路必须具有与声音成正比的电压和电流。
一个高保真的放大系统要尽可能保持模拟量不失真，我们要仔细地设计模拟电子电路以使电压和电流反映输入信号。
An electric circuit (or network) is an interconnection of physical electrical device. The purpose of electric circuits is to distribute and convert energy into some other forms. Accordingly, the basic circuit components are an energy source (or sources), an energy converter (or converters) and conductors connecting them.电路（或者网络）是物理电气设备的一种互相连接。
电路的目的是为了将能量分配和转换到另外一种形式中。
因此，基本的电路元件包括电源、电能转换器以及连接它们的导体。
An energy source (a primary or secondary cell, a generator and the like) converts chemical, mechanical, thermal or some other forms of energy into electric energy. An energy converter, also called load (such as a lamp, heating appliance or electric motor), converts electric energy into light, heat, mechanical work and so on.电源（原生电池或者再生电池、发电机等类似装备）将化学能量、机械能量，热能或者其他形式的能量转换成电能。
电能转换器（也称为负载，如灯泡、电热器或者电动机）将电能转换成光、热、机械运动等等。
【最新整理，下载后即可编辑】Passage 1 Have you ever seen a moon that looks unbelievably big?1.To what do we (all of these)2.The main purpose inform.3.The author mysterious.4.The moon looks it is near the horizon5.The autumn moon helps farmers seePassage 2 Strange thing happens to time when you travel.1.The best title How Time Changes Around the World.2.The difference is one hour.3.From this selection is divided into five time zones.4.The international the point where a new day begins.5.If you cross the ahead one hour in each new time zone.Passage 3 The diner is only a humble restaurant, but it has a special place in American life.1.What’s the main idea of paragraph 2? The attraction of different people.2.The purpose of the last paragraph is to give a summary of the wholepassage.3.Why do truck drivers like a diner?It’s a haven against loneliness.4.Diners rattact many different kinds of people.5.Diners are fascinating.Passage 4 Doctors have known for a long time that extremely loud noises 1.Doctors have long known tha t one may lose his hearing when he hears aterribly loud noise.2.This passage suggests that one’s hearing will be damaged even if he hasheard a loud noise for only little more than one second.3.According to this passage, one conclusion you can draw is that aspirinmakes hearing damage from loud noise worse.lions of Americans are in danger of suffering hearing loss because theytake too much aspirin.5.The purpose of the experiment the American scientist did was to findwhether aspirin would increase the temporary hearing damage from loud noises.Passage 5Just two months ago, Ana, a teenager, was preparing for1.Ana realizes that she must do well on the exam .2.Ana has been studying English for seven years.3.Ana experiences difficulty with the professor’s lecture s.4.Ana tells the interviewers about her family.5.The best main idea for the first paragraph is Ana comes through with flyingcolorsPassage6 Any mistake made in the printing of a stamp raises its value to stamp collectors.1.A postage stamp’s value to colle ctors is raised if a mistake is made in theprinting.2.In 1847 most countries of the world were not yet using postage stamps.3.In 1847, the mistake on the locally printed postage stamps was in thewording4.＄16800 is the collector’s value of the Twopenny Blue.5.The valuable stamps were designed by British printers.Passage 7 The communications explosion is on the scale of the rail, automobile or telephone1.By saying that he takes may images of his children, the author wants todisplay the influence of communications on life .2.The author most probably thinks the communications dust is amazing.3.Which of the following statements about the low-orbit satellites is true?The low-orbit satellites would replace towers and poles functionally.4.According to the passage, an optical-fiber audio-video link can enable us totalk and see each other no matter where we are.5.The phrase “each one”(Line2, para.5) can be best replaced by each car. Passage 8 J apan is getting tough about recycling-and not in the paper andplastic kind of way.1.According to the present regulations of Japan, the recycling of paper andplastic will be the responsibility of the consumers.2.Which of the following is NOT the character of plastics? It retains itsoriginal strength through reprocessing.3.According to the passage, the term “plastic sandwich” refers to a kind ofplastics with different integration in each layer.4.In the passage, it is implied but NOT stated that 21-inch TV withmagnesium case isn’t very popular so far.5.The author writes this passage in order to inform.Passage 9 A friend of mine, in response to a conversation we were having about the injustice1.The author thought of his friend’s question as a good one because like hisfriend, he also thought life was unfair.2.Surrendering to the fact that life isn’t fair will make us know it’s ourduty to perfect things.3.The second paragraph of the passage mainly discusses it’s nice to acceptthe injustice of life.4.In the last paragraph, “this very basic fact” refers to the fact that lifeisn’t and won’t be fair.5.From the passage, we can learn that the author’s attitude to life ispositive.Passage 10 People appear to be born to compute. The numerical skills of children develop so1.What does the passage mainly discuss? The development of mathematicalability in children.2.2.From the passage we can know that children begin to master simplecounting soon after they learn to walk and talk.3.In this passage the author’s attitude towards “children’s numerica lskills” is objective.4.According to the study of psychology, children didn’t think that quantityis unchanged as water pours from one glass to another with a different shape.5.Which of the following statements would be the author most likelydisapprove of? Children learn mathematics naturally and easily. Passage 11 A new technology is going to ripe, one that could transform our daily lives,1.As is indicated in the passage, the technology of superconductivity is stillunder development2.The new technology differs from the others in that it is being cultivated inresearch labs around the world .3.What does the author most probably think of the changes the newtechnology will bring to the world?Dramatic.4.From the passage, we may conclude that Asian scientists gain the lead inthe growth of the new technology.Which of the following would be the best title for the passage? Superconductivity: A New Technology.Passage12 People become quite illogical when they try to decide what can be eaten and what cannot,1.The word “repulsive” most probably means “disgusting”2.We can infer from the second paragraph that when collecting the snails, theauthor was angry because they might damage his beloved plants.3.The author finds that snails are the most controversial food4.The best title of this passage might be “One Man’s Meat is AnotherMan’s Poison “5.As indicated in the passage , people love different foods mainly becauseThey learn to eat certain foods in their families.Passage13 All the useful energy at the surface of the earth comes from the activity of the sun.1.The sun is the source of all of the following EXCEPT atomic power.2.Radiant energy is stored as carbon compounds by plants.3. The sun’s energy provides us with all EXCEPT water4.The largest part of the light energy directed towards the earth is absorbed by the earth’satmosphere5.Of the sun’s total output of radiant energy,the earth receives a very small portionPassage14 The market is a concept .If you are growing tomatoes in you backyard for sale you66.Which of the following would be the best title for the passage? B what’s the market?67.All of the following acts are producing for the market EXCEPT attending a night school68.You are buying from the market when you dine at a restaurant69.The word “real ”in the last paragraph may most probably mean concrete70.In what way is the market very real for eacj person or businessmen who is making and selling something? It tells you what to producePassage15 X-rays were first discovered by a German scientist, Wilhelm Konrad Rontgen,in 1985,1.what puzzled Rontgen one day during his experiment was some radiation coming through the covered tube.2.The screen didn’t stop glowing even when it was moved to the next room3.Rontgen put his hand between the rays and a photographic plate in order to find out more about the rays4.The rays proved to be incapable of passing through bone5.From the passage ,we know X-rays are invisiblePassage16 Body clocks1.According to the passage, one can help maintain balance in the “body clock”2.Irregular signs shown by “body clock” may serve as a warning of possible illnesses3.We tend to do physical exercise early in the afternoon because our body is most active ten4.The author suggests that the best time to study is at nigh t5.According to the passage we are most likely to day-dream every hour in the day time.Passage17 Plastic are materials which are softened by heat san set into lasting form1.The word “sympathetic”in paragraph 2 most probably means agreeable.2.It can be concluded from this passage that plastics are cheap as antiques3.Which of the following is necessary to create any type of plastics? Carbon4.Plastics that harden into permanent shapes are called thermosetting.5.Which of the following is the best title for the passage? The Development of plastics as an Modern MPassage18 When we analyze the salt salinity of ocean waters, we find that it varies only slightly1.This passage mainly tells us about The causes of the variation in oceanic salinity.2.It can be inferred from the passage that increase in the salinity of ocean waters is caused by evaporation.3.Which of the following is not that cause of the decrease in the oceanic salinity? Formation of sea ice.4.Which of the following statements is true according to the whole passage? The temperature of the water has much to do with the oceanic salinity.5.The purpose of mentioning the Weddell Sea is to give an example of cold-water salinity.Passage19 The science of meteorology is concerned with the study of the structure ,1.Which of the following is the best title for the passage? Approaches to the Science of Meteorology.2.The predictions of synoptic meteorologists are directly based on thepreparation and study of weather maps.3.Which of the following is not referred to be the author as a field whose needs are served by weather forecasting? Sports4.The author implies that increased accuracy in weather forecasting will lead to greater protection of human life and property.5.In the last sentence of the passage ,the phrase “these tools”refers to mathematics and physicsPassage20 As we have seen, the focus of medical care in our society has been shifting from1.Today medical care is placing more stress on removing people’s bad living habits.2.In the first paragraph, people are reminded that good health is more than not being ill.3.Traditionally, a person is considered” well” if he is free from any kind of disease.4.According to the author, the true meaning of “wellness” is for people to strive to maintain the best possible health.5.According to what the author advocates, which of the following groups of people would be considered healthy? People who try to be as healthy as possible, regardless of their limitations.Passage21 If you want to teach your children how to say sorry , you must be good at1.If a mother adds “but” to an apology, the child may feel that he owes her an apology.2.According to the author, saying “I’m sorry you ‘re upset”most probably means “I’m aware you’re upset, but I’m not to blame”3.It is not advisable to use the general, all-covering apology because it is vague and ineffective4.We learn from the last paragraph that in teaching children to say sorry their ages should be taken into account.5.It can be inferred from the passage that apologizing properly is not as simple at it seemsPassage22 Scratchy throats, stuffy noses and body aches all spell misery, but being able1.According to the author, knowing the cause of the misery will help shorten the duration of the illness.2.We learn from the passage that over-the-counter drugs can be taken to ease the misery cause by a cold or the flu.3.According to the passage, to combat the flu effectively, one should take medicine upon catching the disease.4.Which of the following symptoms will distinguish the flu from a cold?A high temperature5.If children have flu-like symptoms, their parents are advised not to give them aspirin.Passage23 Sign has become a scientific hot button. Only in the past 20 years have specialists1. The study of sign language is thought to be a challenge to traditional views on the nature of language.2.The present growing interest in sign language was stimulated by an English teacher in a university for the deaf.3.According to Stokoe, sign language is a genuine language4.Most educators objected to Stokoe’s idea because they thought a language could only exist in the form of speech sounds.5.Stokoe’s argument is based on his belief that language is a product of the brain.Passage24 It is hard to track the blue whale, the ocean’s largest creature, which has almost1.The passage is chiefly about the civilian use of a military detection system.2.The underwater listening system was originally designed to trace and locate enemy vessels.3.The deep-sea listening system makes use of the unique property of layers of ocean water in transmitting sound.4.It can be inferred from the passage that military technology has great potential in civilian use5. Which of the following is true about the U.S Navy underwater listening network? It is now partly accessible to civilian scientists.Passage25 You never see them , but they’re with you every time you fly. They record1.What dose the author say about the black box? It is an indispensable device in an airplane2.What information could be found from the black box on the Yemeni airliner? Date for analyzing the cause of the crash.3.Why was the black box redesign in 1965? The early models often got damaged in the crash.4.Why did the Federal Aviation Authority require the black boxes be painted orange or yellow? To makethem easily identifiable.5.What do we know about the black boxer from Air France Flight 447? There is still a good chance of their being recovered.Passage26 New technology links the world as never before. Our planet has shrunk .It’s now1.What is the author’s attitude toward high-teach communications equipment? Positive2.With the increased use of high-teach communications equipment, businesspeople are attaching more importance to their overseas business.3.In this passage, “out of sight and out of main” (lines2-3,part.3) probably means missing opportunities for promotion when abroad4.According to the passage, what is an important consideration of international corporations in employing people today?Ability to speak the client’s language.5.The advantage of employees having foreign language skills is that they can better control the whole negotiation process.Passage27 A properly designed electricalsystem1.when there is some Produce dangerous heat2.Want will circuit breaks It will cut the electrity3.What’s the function of To supply electrity4.Through electrity wiring The electrity meteroutside5.How does a circuit breaker It cuts off electrity supplyPassage28 Every hour the sun beams onto earth1.From the first a technology2.What is the percentage of Less than one thousandth3.Where can photovoltaic cells on rooftops4.In solar thermal power as a heat source5.By what can the sun’s By moveable mirrorsPassage29 Researchers say people traveling1.The main reason A polluted air2.Those who would be women driving in a car3.Which of the following Pollutants from vehicles4.People living near highways more likely to die5.Which of the following Traffic and Heart AttacksPassage30Congratulations. Your decision to stop1.On what does the author On the deciding to quit2.The purpose of the supporting help smokers give up smoking3.Where can people get further From the national newspapers4.Which of the following is a factor Care about the people around you5.What is the author’s opinion about To write down their reasons and always Passage31Unwanted sound,or noise,such as that1.Noise pollution can lower productivity2.Which of the following is the main factor lntensity of sound3.Where is the noise pollution most serious ln airports阅读理解4.Which sound can most people’s ears pick up sound of 15000hertz5.What method is suitable for noise protection wearing ear protection Passage32A smart grid incorporates consumer equipment1.What can customers know through Their electrical consumption and pattern2.One of the advantages of smart grid is customers can save and even sell energy3.What can larger commercial bussiness They can provide power during peak4.What can a smart grid help customers to do To manage their enery consumption wisely5.Which of the following would be Introduction of Smart GridPassage33 In economic terms,electrity is a commodity.An electrity market is a system buy or sell electricity2.What is the price set for short term The principles of supply and damand3.Who will be responsible for managerment Marker operators4.The restuctcring of electic power system is the restructuring of natural gas markets5.Why is Chilean model considered successful Because it has solved several structural problemsPassage34 Large airports with lots of international traffic have employees1.Several languages are spoken to guide passengers in Mang large internationalairports2.How are the airports named in the US? Sometimes they are named after the city they are in3.Which airport can be found in Seattle? Seatac4.Which of the foiiowing statements is True After a long flight of time zones your may5.If you leave your things in the airport,you can the lost and found【最新整理，下载后即可编辑】。
电力专业英语阅读与翻译第一课一、Summary of glossary 术语1.电力系统(electric) power systempower generation 发电transmission system(network) 输电系统(网络)distribution system 配电系统2.发电power generationpower plant 发电厂powerhouse 发电站hydropower plant 水力发电厂nuclear plant 核电厂thermal plant 热电厂fossil-power plant火电厂3.负荷分类load classificationindustrial loads 工业负荷residential loads 居民负荷commercial loads 商业负荷4.拓扑结构system topologyradial system 辐射状系统loop system 环状系统network system 网状系统二、Wording-buildingGeneral Introduction 专业英语词汇和构词方法简介专业词汇的形成主要有三种情况：1.借用日常英语词汇或其他学科的专业词汇，但是词义和词性可能发生了明显的变化。
例如：在日常英语中表示“力量、权力”和在机械专业表示“动力”的power，数学上表示“幂”，在电力专业领域可以仍作为名词，表示“电力、功率、电能”；也可以作为动词，表示“供以电能”。
在日常英语中表示“植物”的plant，在电力专业领域中用来表示“电厂”等。
2.由日常英语词汇或其他学科的专业词汇，直接合成新的词汇。
例如：over和head组合成overhead，表示“架空（输电线）”；super和conductor 合成superconductor，表示“超导体”等。
3.由基本词根和前缀或后缀组成新的词汇。
大部分专业词汇属于这种情况。
实用资料：电气工程专业课(电力类)翻译参考专业外语：Professional English电路（上）electrical circuit (I)电路（下）electrical circuit (II)金工实习machinery practice电机（上）electrical machinery (I)电工实验与测试electrical experiment & test电子综合实践integrated electronic practice信号与系统signal & system电子技术基础（模拟）fundamentals of electronic (analog)电磁场electromagnetic field电子技术实验electronic experiment(I)电子辅助设计EDA Electronic Design Automatic(I)发电厂动力工程基础Heat power engineering in generating plant企业管理enterprise management电气主系统electrical system principle电力系统稳态/暂态分析Steady-State/ Transient-State Analysis of Power System 电力系统继电保护Power System Relaying Protection电力系统潮流计算机分析：Computer Analysis of Power Flow数字电子技术Digital Electrical Technique微机原理microcomputer principle电子技术基础（数字）fundamentals of electronic (digital)自动控制automatic control theory电力系统分析electric power system analysis电子技术基础实验electronic experiment(II)电气主系统课程设计electrical system principle-course design电子辅助设计EDA Electronic Design Automatic(II)通信与计算机网络communication & computer networks电力系统继电保护electric power system relaying电力系统继电保护Power System Protective Relaying电力系统远动技术electric power system remote protocol生产实习productive practice Technology继电保护课程设计electric power system relaying-course design电力电子技术power electronics电力电子技术基础：Fundamentals of Electronics Power Technology电力电子课程设计Power electronics course design电力系统自动控制electric power system control & automation高电压技术High voltage engineering Technology变电站自动化substation automation电力经济electric power system economics电能质量控制electric power quality control配电网自动化distribution system automation电力系统新技术new techniques on electric power system控制电机electrical machine control调度自动化与能量管理energy management & automation灵活交流输电系统flexible AC transmission system计算机保护computer protection电力系统电磁兼容EMC in electric power system毕业实习graduation practice毕业设计graduation dissertation数字信号处理：Digital Signal Processing自动控制理论：Automatic Control Theory电气工程基础：Fundamentals of Electrical Engineering电磁场概论：Introduction to Electro-Magnetic Field计算机继电保护：Microcomputer-Based Relaying Protection电气设备的绝缘检测与故障诊断：Insulation Diagnostics and Troubl-Shooting for Electrical Installations电网规划：Power System Planning可编程控制器原理及应用：Principles of PLC (Programmable logic Controller) And Application电磁场数值计算：Numerical Computation of Electro-Magnetic Field电力系统继电保护：Relay Protection of Power System电力系统自动装置原理The Principle of Electric Power System Automatic Equipment电力通信系统及调度自动化：Power System Communication and Dispatching Automatic专业方向电气工程Electrical Engineering电机与电器Electric Machines and Electric Apparatus电力系统及其自动化Power System and its Automation高电压与绝缘技术High Voltage and Insulation Technology电力电子与电力传动Power Electronics and Power Drives电工理论与新技术Theory and New Technology of Electrical Engineering电子科学与技术Electronics Science and Technology。
第一章第一节电力系统基本结构Part 1 Basic Construction of Electric Power SystemBasic Concepts of Electric Power System电能是一种理想的能力形式，便于传输和使用，而且很清洁，对环境和大气无污染，因此自被发现以来，电能发展迅速并且利用广泛。
电能的产生、输送和消耗过程就在这一被称为电力系统的整体化系统中实现。
Electricity is an ideal energy form, which is convenient to deliver and use, and is clean without polluting our environmentand atmosphere. The generation, delivery and consumption of electricity are realized in an integrated system which is calledelectric power system or power system.一个电力系统包括三个基本部分：发电系统、输电系统和配电系统，如图1-1 所示An electric power system consists of three principal divisions: power generation, power transmission system, and powerdistribution systems, as shown in Fig.1.1图1-1 电力系统的三个基本部分用户从电力系统取用的所有电能都是在某种形式的电厂（或者称作电站）中产生的。
发电是整个电能利用过程的第一环节。
All the electricity the consumers take from the power system is generated in a power plant, or called power station, of somekind. Power generation is the first stage of the whole progress of the utilization of electric energy.输电系统连接发电和配电系统，并经过网络互连通向其他电力系统。
电力专业英语阅读：作业一：将下列段落翻译成中文Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical power supply. It now covers a range of subtopics including power, electronics, control systems, signal processing and telecommunications.Electrical engineering may include electronic engineering. Where a distinction is made, usually outside of the United States, electrical engineering is considered to deal with the problems associated with large-scale electrical systems such as power transmission and motor control, whereas electronic engineering deals with the study of small-scale electronic systems including computers and integrated circuits. Alternatively, electrical engineers are usually concerned with using electricity to transmit energy, while electronic engineers are concerned with using electricity to transmit information. More recently, the distinction has become blurred by the growth of power electronics.Power engineering deals with the generation, transmission and distribution of electricity as well as the design of a range of related devices. These include transformers, electric generators, electric motors, high voltage engineering and power electronics. In many regions of the world, governments maintain an electrical network called a power grid that connects a variety of generators together with users of their energy. Users purchase electrical energy from the grid, avoiding the costly exercise of having to generate their own. Power engineers may work on the design and maintenance of the power grid as well as the power systems that connect to it. Such systems are called on-grid power systems and may supply the grid with additional power, draw power from the grid or do both. Power engineers may also work on systems that do not connect to the grid, called off-grid power systems, which in some cases are preferable to on-grid systems. The future includes Satellite controlled power systems, with feedback in real time to prevent power surges and prevent blackouts.。
第一课定期保养定期保养，简单说是一种有组织的维护计划，用于保持设施或设备处于可能的最好状态，以满足生产的需要。
当然，是否处于可能的最好状态是由组织确定的。
当保养计划定出来后，并不是所有的机械都是在同一个时间实施保养的。
有些设备如果缺乏调整，将会损失很多价值或损失设备的灵敏度，因此，必须首先制定一个完善的周密的保养计划。
保养计划涉及四个领域：润滑，检查，清洗，零件调整和修理。
说到保养，首先是有关润滑的问题，包括润滑剂的型号，使用的润滑工具或系统，润滑计划的综合有效性，润滑步骤以及实施润滑的人员。
检查对所有设备的正常维护是至关重要的，正如人们应定期作体格检查一样，印刷机械也应定期检查。
人和工厂都是相似的。
婴儿需要经常检查，年青人和成年人要经常检查，中年人和老年人更需要检查。
与此相同，新机械需要保养，直到设备转入正常工作为止。
在机械开始磨损前给与较少的关注，会导致更频繁的检查。
如下因素有助于制定印刷设备的检查步骤：使用年限，工作条件，设备价值，服务严紧性，安全要求，连续工作时间，设备的损坏敏感程度，设备的磨损敏感程度，对缺乏调整的敏感程度以及操作者个人的工作经验等。
清洗对保养来说是很有必要的，因为它允许人们对适当润滑，磨损因数，合理的调整以及出现故障进行检查。
以重视的态度对印刷设备做恰当操作同样是重要的。
一台清洁干净的机器可给人们能生产出高质量的印刷品的感觉。
确实，如果人们对这些设备高度重视的话，印刷成品将更令人满意。
如果要使可接受的印刷品成为最终成品，零件的调整与修理必须是基本的定期操作。
有些设备要定期更换某些零件，确定零件的有效寿命，然后在磨损之前更换它。
如果事先知道一个零件的寿命，这是一个极为成功的方法，但是，在印刷厂中，只有极少数零件是有一个预期寿命的，这样，检查计划便有助于确定应何时更换零件。
如果机器的调整能确保印刷成品一致的印刷质量，同时降低成本，那么，磨损因数将会降低。
一个定期维护计划只有在印刷质量水平能维持住，并能延长机器的有效寿命时才是有效的。
Passage 1Have you ever seen a moon that looks unbelievably big?1.To what do we <all of these>2.The main purpose inform.3.The author mysterious.4.The moon looks it is near the horizon5.The autumn moon helps farmers seePassage 2Strange thing happens to time when you travel.1.The best title How Time Changes Around the World.2.The difference is one hour.3.From this selection is divided into five time zones.4.The international the point where a new day begins.5.If you cross the ahead one hour in each new time zone.Passage 3 The diner is only a humble restaurant, but it has a special place in American life.1.What’s the main idea of paragraph 2? The attraction of different people.2.The purpose of the last paragraph is to give a summary of the whole passage.3.Why do truck drivers like a diner?It’s a haven against loneliness.4.Diners rattact many different kinds of people.5.Diners are fascinating.Passage 4Doctors have known for a long time that extremely loud noises1.Doctors have long known tha t one may lose his hearing when he hears a terribly loud noise.2.This passage suggests that one’s hearing will be damaged even if he has heard a loud noise for onlylittle more than one second.3.According to this passage, one conclusion you can draw is that aspirin makes hearing damage fromloud noise worse.lions of Americans are in danger of suffering hearing loss because they take too much aspirin.5.The purpose of the experiment the American scientist did was to find whether aspirin would increasethe temporary hearing damage from loud noises.Passage 5Just two months ago, Ana, a teenager, was preparing for1.Ana realizes that she must do well on the exam .2.Ana has been studying English for seven years.3.Ana experiences difficulty with the professor’s lectures.4.Ana tells the interviewers about her family.5.The best main idea for the first paragraph is Ana comes through with flying colorsPassage6 Any mistake made in the printing of a stamp raises its value to stamp collectors.1. A postage stamp’s value to collectors is raised if a mistake is made in the printing.2.In 1847 most countries of the world were not yet using postage stamps.3.In 1847, the mistake on the locally printed postage stamps was in the wording4.＄16800 is the collector’s value of the Twopenny Blue.5.The valuable stamps were designed by British printers.Passage 7 The communications explosion is on the scale of the rail, automobile or telephone1.By saying that he takes may images of his children, the author wants to display the influence ofcommunications on life .2.The author most probably thinks the communications dust is amazing.3.Which of the following statements about the low-orbit satellites is true? The low-orbit satellites wouldreplace towers and poles functionally.4.According to the passage, an optical-fiber audio-video link can enable us to talk and see each other nomatter where we are.5.The phrase "each one"<Line2, para.5> can be best replaced by each car.Passage 8 J apan is getting tough about recycling-and not in the paper and plastic kind of way.1.According to the present regulations of Japan, the recycling of paper and plastic will be theresponsibility of the consumers.2.Which of the following is NOT the character of plastics? It retains its original strength throughreprocessing.3.According to the passage, the term "plastic sandwich" refers to a kind of plastics with differentintegration in each layer.4.In the passage, it is implied but NOT stated that 21-inch TV with magnesium case isn’t very popularso far.5.The author writes this passage in order to inform.Passage 9 A friend of mine, in response to a conversation we were having about the injustice1.The author thought of his friend’s question as a good one because like his friend, he also thought lifewas unfair.2.Surrendering to the fact that life isn’t fair will mak e us know it’s our duty to perfect things.3.The second paragraph of the passage mainly discusses it’s nice to accept the injustice of life.4.In the last paragraph, "this very basic fact" refers to the fact that life isn’t and won’t be fair.5.From the passage, we can learn that the author’s attitude to life is positive.Passage 10 People appear to be born to compute. The numerical skills of children develop so1.What does the passage mainly discuss? The development of mathematical ability in children.2. 2.From the passage we can know that children begin to master simple counting soon after they learntowalk and talk.3.In this passage the author’s attitude towards "children’s numerical skills" is objective.4.According to the study of psychology, children didn’t think that quantity is unchanged as water poursfrom one glass to another with a different shape.5.Which of the following statements would be the author most likely disapprove of? Children learnmathematics naturally and easily.Passage 11 A new technology is going to ripe, one that could transform our daily lives,1.As is indicated in the passage, the technology of superconductivity is still under development2.The new technology differs from the others in that it is being cultivated in research labs around theworld .3.What does the author most probably think of the changes the new technology will bring to theworld?Dramatic.4.From the passage, we may conclude that Asian scientists gain the lead in the growth of the newtechnology.Which of the following would be the best title for the passage? Superconductivity: A New Technology. Passage12 People become quite illogical when they try to decide what can be eaten and what cannot,1.The word "repulsive" most probably means "disgusting"2.We can infer from the second paragraph that when collecting the snails, the author was angry becausethey might damage his beloved plants.3.The author finds that snails are the most controversial food4.The best title of this passage might be "One Man’s Meat is Another Man’s Poison "5.As indicated in the passage , people love different foods mainly because They learn to eat certainfoods in their families.Passage13 All the useful energy at the surface of the earth comes from the activity of the sun.1.The sun is the source of all of the following EXCEPT atomic power.2.Radiant energy is stored as carbon compounds by plants.3.The sun’s energy provides us with all EXCEPT water4.The largest part of the light energy directed towards the earth is absorbed by the earth’satmosphere5.Of the sun’s total output of radiant energy,the earth receives a very small portionPassage14 The market is a concept .If you are growing tomatoes in you backyard for sale you66.Which of the following would be the best title for the passage? B what’s the market?67.All of the following acts are producing for the market EXCEPT attending a night school68.You are buying from the market when you dine at a restaurant69.The word"real "in the last paragraph may most probably mean concrete70.In what way is the market very real for eacj person or businessmen who is making and selling something?It tells you what to producePassage15 X-rays were first discovered by a German scientist, Wilhelm Konrad Rontgen,in 1985,1.what puzzled Rontgen one day during his experiment was some radiation coming through the covered tube.2.The screen didn’t stop glowing even when it was moved to the next room3.Rontgen put his hand between the rays and a photographic plate in order to find out more about the rays4.The rays proved to be incapable of passing through bone5.From the passage ,we know X-rays are invisiblePassage16 Body clocks1.According to the passage, one can help maintain balance in the "body clock"2.Irregular signs shown by "body clock" may serve as a warning of possible illnesses3.We tend to do physical exercise early in the afternoon because our body is most active ten4.The author suggests that the best time to study is at nigh t5.According to the passage we are most likely to day-dream every hour in the day time.Passage17 Plastic are materials which are softened by heat san set into lasting form1.The word "sympathetic"in paragraph 2 most probably means agreeable.2.It can be concluded from this passage that plastics are cheap as antiques3.Which of the following is necessary to create any type of plastics? Carbon4.Plastics that harden into permanent shapes are called thermosetting.5.Which of the following is the best title for the passage? The Development of plastics as an Modern M Passage18 When we analyze the salt salinity of ocean waters, we find that it varies only slightly1.This passage mainly tells us about The causes of the variation in oceanic salinity.2.It can be inferred from the passage that increase in the salinity of ocean waters is caused by evaporation.3.Which of the following is not that cause of the decrease in the oceanic salinity? Formation of sea ice.4.Which of the following statements is true according to the whole passage? The temperature of the water has much to do with the oceanic salinity.5.The purpose of mentioning the Weddell Sea is to give an example of cold-water salinity.Passage19 The science of meteorology is concerned with the study of the structure ,1.Which of the following is the best title for the passage? Approaches to the Science of Meteorology.2.The predictions of synoptic meteorologists are directly based on the preparation and study of weather maps.3.Which of the following is not referred to be the author as a field whose needs are served by weather forecasting? Sports4.The author implies that increased accuracy in weather forecasting will lead to greater protection of human life and property.5.In the last sentence of the passage ,the phrase "these tools" refers to mathematics and physicsPassage20 As we have seen, the focus of medical care in our society has been shifting from1.Today medical care is placing more stress on removing people’s bad living habits.2.In the first paragraph, people are reminded that good health is more than not being ill.3.Traditionally, a person is considered" well" if he is free from any kind of disease.4.According to the author, the true meaning of "wellness" is for people to strive to maintain the best possible health.5.According to what the author advocates, which of the following groups of people would be considered healthy? People who try to be as healthy as possible, regardless of their limitations.Passage21 If you want to teach your children how to say sorry , you must be good at1.If a mother adds "but" to an apology, the child may feel that he owes her an apology.2.According to the author, saying "I’m sorry you ‘re upset" most probably means "I’m aware you’re upset, but I’m not to blame"3.It is not advisable to use the general, all-covering apology because it is vague and ineffective4.We learn from the last paragraph that in teaching children to say sorry their ages should be taken into account.5.It can be inferred from the passage that apologizing properly is not as simple at it seemsPassage22 Scratchy throats, stuffy noses and body aches all spell misery, but being able1.According to the author, knowing the cause of the misery will help shorten the duration of the illness.2.We learn from the passage that over-the-counter drugs can be taken to ease the misery cause by a cold or the flu.3.According to the passage, to combat the flu effectively, one should take medicine upon catching the disease.4.Which of the following symptoms will distinguish the flu from a cold? A high temperature5.If children have flu-like symptoms, their parents are advised not to give them aspirin.Passage23 Sign has become a scientific hot button. Only in the past 20 years have specialists1. The study of sign language is thought to be a challenge to traditional views on the nature of language.2.The present growing interest in sign language was stimulated by an English teacher in a university for the deaf.3.According to Stokoe, sign language is a genuine language4.Most educators objected to Stokoe’s idea because they thought a language could only exist in the form of speech sounds.5.Stokoe’s argument is based on his belief that language is a product of the brain.Passage24 It is hard to track the blue whale, the ocean’s largest creature, which has almost1.The passage is chiefly about the civilian use of a military detection system.2.The underwater listening system was originally designed to trace and locate enemy vessels.3.The deep-sea listening system makes use of the unique property of layers of ocean water in transmitting sound.4.It can be inferred from the passage that military technology has great potential in civilian use5. Which of the following is true about the U.S Navy underwater listening network?It is now partly accessible to civilian scientists.Passage25 Y ou never see them , but they’re with you every time you fly. They record1.What dose the author say about the black box? It is an indispensable device in an airplane2.What information could be found from the black box on the Yemeni airliner? Date for analyzing the cause of the crash.3.Why was the black box redesign in 1965? The early models often got damaged in the crash.4.Why did the Federal Aviation Authority require the black boxes be painted orange or yellow? To make them easily identifiable.5.What do we know about the black boxer from Air France Flight 447? There is still a good chance of their being recovered.Passage26 New technology links the world as never before. Our planet has shrunk .It’s now1.What is the author’s attitude toward high-teach communications equipment? Positive2.With the increased use of high-teach communications equipment, businesspeople are attaching more importance to their overseas business.3.In this passage, "out of sight and out of main" <lines2-3,part.3> probably means missing opportunities for promotion when abroad4.According to the passage, what is an important consideration of international corporations in employing people today? Ability to speak the client’s language.5.The advantage of employees having foreign language skills is that they can better control the whole negotiation process.Passage27 A properly designed electricalsystem1.when there is some Produce dangerous heat2.Want will circuit breaks It will cut the electrity3.What’s the function of To supply electrity4.Through electrity wiring The electrity meteroutside5.How does a circuit breaker It cuts off electrity supplyPassage28 Every hour the sun beams onto earth1.From the first a technology2.What is the percentage of Less than one thousandth3.Where can photovoltaic cells on rooftops4.In solar thermal power as a heat source5.By what can the sun’s By moveable mirrorsPassage29 Researchers say people traveling1.The main reason A polluted air2.Those who would be women driving in a car3.Which of the following Pollutants from vehicles4.People living near highways more likely to die5.Which of the following Traffic and Heart AttacksPassage30Congratulations. Your decision to stop1.On what does the author On the deciding to quit2.The purpose of the supporting help smokers give up smoking3.Where can people get further From the national newspapers4.Which of the following is a factor Care about the people around you5.What is the author’s opinion about To write down their reasons and alwaysPassage31Unwanted sound,or noise,such as that1.Noise pollution can lower productivity2.Which of the following is the main factor lntensity of sound3.Where is the noise pollution most serious ln airports4.Which sound can most people’s ears pick up sound of 15000hertz5.What method is suitable for noise protection wearing ear protectionPassage32A smart grid incorporates consumer equipment1.What can customers know through Their electrical consumption and pattern2.One of the advantages of smart grid is customers can save and even sell energy3.What can larger commercial bussiness They can provide power during peak4.What can a smart grid help customers to do To manage their enery consumption wisely5.Which of the following would be Introduction of Smart GridPassage33 In economic terms,electrity is a commodity.An electrity market is a system buy or sell electricity2.What is the price set for short term The principles of supply and damand3.Who will be responsible for managerment Marker operators4.The restuctcring of electic power system is the restructuring of natural gas markets5.Why is Chilean model considered successful Because it has solved several structural problems Passage34 Large airports with lots of international traffic have employees1.Several languages are spoken to guide passengers in Mang large internationalairports2.How are the airports named in the US?Sometimes they are named after the city they are in3.Which airport can be found in Seattle?Seatac4.Which of the foiiowing statements is True After a long flight of time zones your may5.If you leave your things in the airport,you can the lost and found。
电力专业英语阅读与翻译第一课一、Summary of glossary 术语1.电力系统(electric) power systempower generation 发电transmission system(network) 输电系统(网络)distribution system 配电系统2.发电power generationpower plant 发电厂powerhouse 发电站hydropower plant 水力发电厂nuclear plant 核电厂thermal plant 热电厂fossil-power plant火电厂3.负荷分类load classificationindustrial loads 工业负荷residential loads 居民负荷commercial loads 商业负荷4.拓扑结构system topologyradial system 辐射状系统loop system 环状系统network system 网状系统二、Wording-buildingGeneral Introduction 专业英语词汇和构词方法简介专业词汇的形成主要有三种情况：1.借用日常英语词汇或其他学科的专业词汇，但是词义和词性可能发生了明显的变化。
例如：在日常英语中表示“力量、权力”和在机械专业表示“动力”的power，数学上表示“幂”，在电力专业领域可以仍作为名词，表示“电力、功率、电能”；也可以作为动词，表示“供以电能”。
在日常英语中表示“植物”的plant，在电力专业领域中用来表示“电厂”等。
2.由日常英语词汇或其他学科的专业词汇，直接合成新的词汇。
例如：over和head组合成overhead，表示“架空（输电线）”；super和conductor 合成superconductor，表示“超导体”等。
3.由基本词根和前缀或后缀组成新的词汇。
大部分专业词汇属于这种情况。
PART1U1T1、In addition to the various power transformers, two special-purpose transformers are used with electric machinery and power systems。
The first of these special transformers is a device specially designed to sample a high voltage and produce a low secondary voltage directly proportional to it. Such a transformer is a potential transformer. A power transformer also produces a secondary voltage directly proportional to that the potential transformer is designed to handle only a very small current。
The second type of special transformer is a device designed to provide a secondary current much smaller than but directly proportional to its primary current. This device is called a current transformer。
除了各种电源变压器、两个专用变压器使用电动机械和电力系统。
第一个特殊变压器是一个高电压设备专门设计的样品和生产较低的二次电压成正比。
这样一个变压器电压互感器。
电力变压器也产生二次电压成正比的电压互感器的设计目的是处理只有一个很小的电流。
A decrease in the field current gives rise to lagging (inductive) current in the stator; and increase in the field current that overexcites the motor causes a leading (capacitive) current to appear in the stator.励磁电流减小时，定子电流感性增强；励磁电流增加使电机过励时将在定子中产生容性电流。
An induction machine is an AC two-winding unit in which only one (primary, usually the stator) winding is supplied with an alternating current at a constant frequency ω1 from an external source.感应电机是一种具有双绕组的交流电气设备，它只有一个绕组（一次侧，通常是定子）通过外电源输入固定频率为ω1的交变电流。
Current transformers for protection are essentially similar to those used for the operation of ammeters, watthourmeters and other instruments.保护用电流互感器基本上同操作用的电流表、电能表和其他仪器类似。
DG planning also involves arranging for connection of the renewable power generator with the local grid, and for support of any local electric load when the renewable source is not available.分布式发电规划还包括安排可再生能源发电机与地方电网相连接，这样当可再生能源不可用时，本地电力负荷仍能得到支持。
Semiconductor switches are very important and crucial components in power electronic systems.these switches are meant to be the substitutions of the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing. 在电力电子系统，中半导体开关是非常重要和关键部件。
半导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。
Switching losses开关损耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses. 电力电子转换器的功率损耗分为开关损耗和寄生损耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses of capacitors,the eddy and the hysteresis losses. 寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗the switching losses are significant and can be managed. 这个开关损耗是非常重要的,可以被处理。
they can be further divided into three components:(a)the on-state losses,(b)the off-state losses and the losses in the transition states. 他们可以分为三个部分: 通态损耗，断态损耗和转换过程中产生的损耗。
第一章第一节电力系统基本结构Part 1 Basic Construction of Electric Power SystemBasic Concepts of Electric Power System电能是一种理想的能力形式，便于传输和使用，而且很清洁，对环境和大气无污染，因此自被发现以来，电能发展迅速并且利用广泛。
电能的产生、输送和消耗过程就在这一被称为电力系统的整体化系统中实现。
Electricity is an ideal energy form, which is convenient to deliver and use, and is clean without polluting our environmentand atmosphere. The generation, delivery and consumption of electricity are realized in an integrated system which is calledelectric power system or power system.一个电力系统包括三个基本部分：发电系统、输电系统和配电系统，如图1-1所示。
An electric power system consists of three principal divisions: power generation, power transmission system, and powerdistribution systems, as shown in Fig.1.1图1-1电力系统的三个基本部分用户从电力系统取用的所有电能都是在某种形式的电厂（或者称作电站）中产生的。
发电是整个电能利用过程的第一环节。
All the electricity the consumers take from the power system is generated in a power plant, or called power station, of somekind. Power generation is the first stage of the whole progress of the utilization of electric energy.输电系统连接发电和配电系统，并经过网络互连通向其他电力系统。
配电系统在执行电压变换和开关功能的变电站将所有单个负荷接连到输电线路。
Transmission systems are the connecting links between the generation plants and the distribution systems and lead to otherpower systems over interconnections. A distribution system connects all the individual loads to the transmission lines at thesubstations which perform voltage transformation and switching functions.地处负荷区的附近的小型电厂，通常直接连接到中压输电系统或配电系统。
Small generating plants located near the load are often connected to the subtransmission or distribution system directly.通常，在输电系统水平上形成相邻电力系统间的互联。
Interconnection to neighboring power systems are usually formed at the transmission system level.因而整个电力系统包括多个电源和若干层次的输电网络。
这提供了高度的结构化冗余，使系统能够承受罕见的意外事故而不会中断对用户的供电。
The overall system thus consists of multiple generating sources and several layers of transmission networks. This provides ahigh degree of structural redundancy that enables the system to withstand unusual contingencies without service disruption tothe consumers.第二节电力系统典型的网络拓扑结构Part 2 Typical Topologies of Electric Power System构成电力系统的设备，其布局取决于当地的负荷增长方式，并且随时可能重新调整。
The equipments which form an electric system are arranged depending on the manner in which load grows in the area and may berearranged from time to time.然而，也可以采取办法对系统进行分类。
以下列举三类：辐射状系统、环状系统和网状系统。
However, there are certain plans into which a particular system design may be classified. Three types are illustrated: theradial system, the loop system and the network system.如图1-2所示，在辐射系统中，线路从电源呈树状向外延伸。
打开任一段线路都会导致一个或多个负荷停电。
In a rad ial system, as shown in Fig. 1.1, the lines form a “tree” spreading out from the power source. Opening any linewill result in interruption of power to one or more of the loads.环状系统如图1-3所示。
这样接线，即使一条线路退出运行，仍能保证给所有负荷供电。
The loop system is illustrated in Fig. 1.2. With this arrangement all loads may be served even though one line section isremoved from service.图1-4所示的是同样的负载由网状方式供电。
这样设计，保证了每个负荷有两条或多条线路为其供电。
Fig. 1.3 shows the same loads being served by a network. With this arrangement each load has two or more circuits over whichit is fed.通常将配电线路设计成辐射状或环状，但是大多数高压输电线路则按网状布局，主要电力系统的互联形成由多个线路段组成的网络。
Distribution circuits are commonly designed so that they may be classified as radial or loop circuit. The high-voltagetransmission lines of most power systems are arranged as networks. The interconnection of major power systems result innetworks made up many line sections.第三节大多数电力系统的特点Part 3 Characteristics of Most Power System第一个完整的电力系统是直流系统。
交流输电的发展，促成了交流电力系统的产生。
由于下列原因，交流系统已经完全取代直流系统。
The first complete electric power system was a direct current (DC) system. The development of alternating current (AC)transmission led to AC electric power system. The AC system had won out over the DC system for the following reasons:（1）交流系统易于转换电压等级，因而提供了以不同电压水平进行发电、输电和用电的灵活性。
i ) V oltage levels can be easily transformed in AC systems, thus providing the flexibility for use of different voltage forgeneration, transmission, and consumption.（2）与直流电机相比，交流电机要更加简单和便宜。
ii) AC electric machines are much simpler or cheaper than DC electric machines.电力系统的大小和结构组成可能不同。
然而，它们有相同的基本特点Electric power systems vary in size and structural components. However, they all have the same basic characteristics:（1）电力系统都是由基本运行在恒定电压的三相交流系统构成。
发电和输电设备都是三相元件。
工业负荷总是三相负载；单相居民负荷和商业在各相之间均匀分配，以有效地构成平衡的三相系统。
i) Are comprised of three-phase AC systems operating essentially at constant voltage. Generation and transmission facilitiesuse three-phase equipment. Industrial loads are invariably three-phase; single-phase residential and commercial loads aredistributed equally among the phases so as to effectively form a balanced three-phase system.（2）都使用同步电机发电。
