专业英语P1U7教学课件.ppt

1、自动化专业英语教程,教学课件,July 28, 2007,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,A 电力系统 1. 课文内容简介：主要介绍专业课工厂供电技术中电力系统的组成、供电故障、供电质量、保护等内容。 2. 温习工厂供电技术中讲述电网构成与绿色能源等内容。 3. 生词与短语 transformer n. 变压器 substation n. 变电站 prime mover 原动机 turbine t:bin n. 涡轮 Aluminum 英音：lju:minm美音：lumnm n. 铝 copper-clad n. 镀铜 suspend

2、v. 悬挂 latticework n. 格子 porcelain：p:slin adj. 瓷制的 supplementary adj. 辅助的 circuit breaker 断路器,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,immerse v. 沉浸，浸入 quench v. 熄灭 wiring n. 配线 alloy n. 合金 grid n. 格子，网格 reserve capacity 储备功率 blackout n. （大区域的）停电 outage autid n. 暂时停电 landslide n. 泥石流 sabotage sbt

3、: n. 破坏 sophisticated adj. 复杂精密的 continuity ,kntinju:iti n. 连续性 constancy n. 恒定 synchronous condenser 同步调相机 nullify nlifai v. 无效 pollutant plu:tnt n. 污染物质,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,off-peak adj. 非高峰的 geothermal ,di:u:ml adj. 地热的 4. 难句翻译 1 In cities and other areas where open lines

4、 create a safety hazard or are considered unattractive, insulated underground cables are used for distribution. 在城市和其它地区，明线存在安全隐患或者被认为影响美观，所以使用绝缘地下电缆进行配电。 2 Each utility that agrees to share gains an increased reserve capacity, use of larger, more efficient generators, and the ability to respond to

5、local power failures by obtaining energy from a linking grid. 同意共享的每个电力企业可以获得不断增加的储备功率，使用更大、效率更高的发电机，从电网中获取电能以应对局部电力故障。,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,3 Inductance and capacitance react with a tendency to nullify one another. 电感和电容的作用能相互抵消。,Electric Power System Introduction Electric P

6、ower Systems, components that transform other types of energy into electrical energy and transmit this energy to a consumer. The production and transmission of electricity is relatively efficient and inexpensive, although unlike other forms of energy, electricity is not easily stored and thus must g

7、enerally be used as it is being produced.,Components of an Electric Power System,A modem electric power system consists of six main components: (1) the power station, (2) a set of transformers to raise the generated power to the high voltages used on the transmission lines, (3) the transmission line

8、s, (4) the substations at which the power is stepped down to the voltage on the distribution lines, (5) the distribution lines, and (6) the transformers that lower the distribution voltage to the level used by the consumers equipment.,Power Station The power station of a power system consists of a p

9、rime mover, such as a turbine driven by water, steam, or combustion gases that operate a system of electric motors and generators. Most of the worlds electric power is generated in steam plants driven by coal, oil, nuclear energy, or gas. A smaller percentage of the worlds electric power is generate

10、d by hydroelectric (waterpower), diesel, and internal-combustion plants.,Transformers Modern electric power systems use transformers to convert electricity into different voltages. With transformers, each stage of the system can be operated at an appropriate voltage. In a typical system, the generat

11、ors at the power station deliver a voltage of from 1,000 to 26,000 volts (V), Transformers step this voltage up to values ranging from 138,000 to 765,000 V for the long-distance primary transmission line because higher voltages can be transmitted more efficiently over long distance.,At the substatio

12、n the voltage may be transformed down to levels of 69,000 to 138,000V for further transfer on the distribution system. Another set of transformers step the voltage down again to a distribution level such as 2,400 or 4,160 V or 15, 27, or 33 kilovolts (kV). Finally the voltage is transformed once aga

13、in at the distribution transformer near the point of use to 240 or 120 V.,Transmission Lines The lines of high-voltage transmission systems are usually composed of copper, aluminum, or copper-clad or aluminum-clad steel, which are suspended from tall latticework towers of steel by strings of porcela

14、in insulators. By the use of clad steel wires and high tower, the distance between towers can be increased, and the cost of the transmission line thus reduced. In modern installations with essentially straight paths, high-voltage lines may be built with as few as six towers to the kilometer. In some

15、 areas high-voltage lines are suspended from tall wooden poles spaced more closely together.,For lower voltage distribution lines, wooden poles are generally used rather than steel towers. In cities and other areas where open lines create a safety hazard or are considered unattractive, insulated und

16、erground cables are used for distribution. Some of these cables have a hollow core through which oil circulates under low pressure. The oil provides temporary protection from water damage to the enclosed wires should the cable develop a leak. Pipe-type cables in which three cables are enclosed in a

17、pipe filled will oil under high pressure (14 kg per sq cm/200psi) are frequently used. These cables are used for transmission of current at voltages as high as 345,000 V (or 345 kV).,Supplementary Equipment Any electric-distribution system involves a large amount of supplementary equipment to protec

18、t the generators, transformers, and the transmission lines themselves. The system often includes devices designed to regulate the voltage or other characteristics of power delivered to consumers.,To protect all elements of a power system form short circuits and overloads, and for normal switching op

19、erations, circuit breakers are employed. These breakers are large switches that are activated automatically in the event of a short circuit or other condition that produces a sudden rise of current. Because a current forms across the terminals of the circuit breaker at the moment when the current is

20、 interrupted, some large breakers (such as those used to protect a generator or a section of primary transmission line) are immersed in a liquid that is a poor conductor of electricity, such as oil, to quench the current.,In large air-type circuit breakers, as well as in oil breakers, magnetic field

21、s are used to break up the current. Small air-circuit breakers are used for protection in shops, factories, and in modern home installations. In residential electric wiring, fuses were once commonly employed for the same purpose. A fuse consists of a piece of alloy with a low melting point, inserted

22、 in the circuit, which melts, breaking the circuit if the current rises above a certain value. Most residences now use air-circuit breakers.,In most parts of the world, local or national electric utilities have joined in grid systems. The linking grids allow electricity generated in one area to be s

23、hared with others. Each utility that agrees to share gains an increased reserve capacity, use of larger, more efficient generators, and the ability to respond to local power failures by obtaining energy from a linking grid.,Power Failures,These interconnected grids are large, complex systems that co

24、ntain elements operated by different groups. These systems offer the opportunity for economic savings and improve overall reliability but can create a risk of widespread failure. For example, the worst blackout in the history of the United States and Canada occurred August 14, 2003, when 61,800 mega

25、watts of electrical power was lost in an area covering 50 million people. (One megawatt of electricity is roughly the amount needed to power 750 residential homes.) The blackout prompted calls to replace aging equipment and raised questions about the reliability of the national power grid.,Despite t

26、he potential for rate widespread problems, the interconnected grid system provides necessary backup and alternate paths for power flow, resulting in much higher overall reliability than is possible with isolated systems. National or regional grids can also cope with unexpected outages such as those

27、caused by storms, earthquakes, landslides, and forest fires, or due to human error or deliberate acts of sabotage.,In recent years electricity has been used to power more sophisticated and technically complex manufacturing processes, computers and computer networks, and a variety of other high-techn

28、ology consumer goods. These products and processes are sensitive not only to the continuity of power supply but also to the constancy of electrical frequency and voltage. Consequently, utilities are taking new measures to provide the necessary reliability and quality of electrical power, such as by

29、providing additional electrical equipment to assure that the voltage and other characteristics of electrical power are constant.,Power Quality,Voltage Regulation Long transmission lines have considerable inductance and capacitance. When a current flows through the line, inductance and capacitance ha

30、ve the effect of varying the voltage on the line as the current varies. Thus the supply voltage varies with the load. Several kinds of devices are used to overcome this undesirable variation in an operation called regulation of the voltage. The devices induction regulators and three-phase synchronou

31、s motors (called synchronous condensers), both of which vary the effective amount of inductance and capacitance in the transmission circuit.,Inductance and capacitance react with a tendency to nullify one another. When a load circuit has more inductive than capacitive reactance, as almost invariably

32、 occurs in large power systems, the amount of power delivered for a given voltage and current is less than when the two are equal. The ratio of these two amounts of power is called the power factor. Because transmission-line losses are proportional to current, capacitance is added to the circuit whe

33、n possible, thus bringing the power factor as nearly as possible to 1. For this reason, large capacitors are frequently inserted as a part of power-transmission systems.,World Electric Power Production Over the period from 1950 to 2003, the most recent year for which data are available, annual world

34、 electric power production and consumption rose from slightly less than 1 trillion kilowatt-hours(k W. h ) to 15.9 trillion k W. h. A change also took place in the type of power generation. In 1950 about two-thirds of the worlds electricity came from steam-generating sources and about one-third from

35、 hydroelectric sources. In 2003 thermal sources produced 65 percent of the power, but hydropower had declined to 17 percent, and nuclear power accounted for 16 percent of the total. The growth in nuclear power slowed in some countries, notably the United States, in response to concerns about safety.

36、 Nuclear plants generated 20 percent of U.S. electricity in 2003; in France, the world leader, the figure was 78 percent.,Much of the worlds electricity is produced from the use of nonrenewable resources, such as natural gas, coal, oil, and uranium. Coal, oil, and natural gas contain carbon, and bur

37、ning these fossil fuels contributes to global emissions of carbon dioxide and other pollutants. Scientists believe that carbon dioxide is the principal gas responsible for global warming, a steady rise in Earths surface temperature.,Conservation,Consumers of electricity can save money and help prote

38、ct the environment by eliminating unnecessary use of electricity, such as turning off lights when leaving a room. Other conservation methods include buying and using energy-efficient appliances and light bulbs, and using appliances, such as washing machines and dryers, at off-peak production hours w

39、hen rates are lower. Consumers may also consider environmental measures such as purchasing “green power” when it is offered by a local utility. “Green power” is usually more expensive but relies on renewable and environmentally friendly energy sources, such as wind turbines and geothermal power plan

40、ts.,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,5. 参考译文 A 电力系统 介绍 电力系统把其它形式的能源转化为电能并输送给用户。尽管不同于其它形式的能源，电能不容易储存，一旦生产出来，必须得到使用，但是电力的生产和传输相对高效和廉价。 电力系统的组成 当今的电力系统由六个主要部分组成：电站，升压变压器（将发出来的电升压至传输线所需高电压），传输线，变电站（电压降至配电线电压等级），配电线路和降压变压器（将配电电压降至用户设备使用的电压水平）。,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,1、电站

41、。电力系统的电站包括原动机，如由水，蒸汽驱动的涡轮，或者燃烧气体操控的电动机和发电机系统，世界上大多数的电能由煤炭、石油、核能或者燃气驱动的蒸汽发电厂产生。少量电能由水力，柴油和内燃机发电厂产生。 2、变压器。现代电力系统使用变压器把电能转换为不同的电压。有了变压器，系统的每个阶段都能在合适的电压等级下运行。在典型的系统中，电站发电机发出的电压范围是1000伏到26000伏。变压器把电压升至138000到765000伏后，送至主传输线上。因为对于长距离传输，电压越高，效率越高。在变电站，电压被降至69000到138000伏，以便在配电系统中传输。另外一组变压器把电压进一步降至配电等级，如240

42、0到4160伏，或者15，27，33KV。最终，在使用端，经配电变压器，电压再次被降至240V或120V。 3、传输线。高压传输系统通常由铜线、铝线或者镀铜、镀铝的钢线组成，它们悬挂在高大钢格构塔架上成串的,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,瓷质绝缘体上。由于含镀层钢线和铁塔的使用，增大了塔与塔之间的距离，降低了传输线的成本。在当前的直线安装中，每公里高压线只需建立6个铁塔。在一些地区，高压线悬挂于距离较近的木质电线杆上。 对于低压配电线路，更多的使用木质电线杆，而不是铁塔。在城市和一些地区，明线存在安全危险或者被认为影响美观，所以使用绝

43、缘地下电缆进行配电。一些电缆内核中空，供低压油循环。油可以为防止水对封闭线路的破坏提供临时保护。通常使用管式电缆，三根电缆放入线管中，并填满高压油。这些电缆用于传输高达345KV的电流。 4、辅助设备。每个配电系统包含大量辅助设备来保护发电机、变压器和传输线。系统通常还包括用来调整电压或用户端其它电力特性的设备。 为了保护电力系统设施，防止短路和过载，对于正常的开关操作，采用断路器。断路器是大型开关，在短路时或者电流突然上升的情况下自动切断电源。由于电流断开时，断路器触点两端会形成电流，一些大型断路器（如那些用来保护发电机和主输电线的断路器）通常浸入绝缘液体里面，如,P1U7A Electri

44、c Power System 第一部分第七单元课文A 电力系统,油，以熄灭电流。在大型空气开关和油断路器中，使用磁场来削弱电流。小型空气开关用于商场，工厂和现代家庭设备的保护。在住宅电气布线中，以前普遍采用保险丝。保险丝由熔点低的合金组成，安装在电路中，当电流超过一定值，它会熔断，切断电路。现在绝大多数住宅使用空气断路器。 供电故障 世界上大多数地方，局部或全国电力设施都连成电网。电网可以使发电实现区域共享。同意共享的每个电力企业可以获得不断增加的储备功率，使用更大、效率更高的发电机，从电网中获取电能以应对局部电力故障。 互联的电网是大型复杂系统，包括被不同组织操控的部分。这些系统可以节约开支

45、，提高整体可靠性，但是也带来了大范围停电的风险。例如，2003年8月14日，美国和加拿大发生了历史上最严重的停电事故。当时，这个区域61800兆瓦的电力供应中断，五千万人口受到影响。（一兆瓦大约可以满足750居民的用电需求）。停电事件迫切要求更新老化设备，提出关于全国电网可靠性的问题。,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,尽管存在大范围停电危险，互联电网提供了必要的备份措施和供替换的线路，相对于孤立系统，其整体可靠性要高得多。国家或地区电网还可以应对由暴风雨、地震、泥石流、森林火灾、人员操作错误或者蓄意破坏造成的意外停电。 供电质量 近年来

46、，越来越多的精密复杂生产过程、计算机和网络及许多高科技消费品都使用电力为其提供能量。这些产品和生产过程对于供电的连续性和电压、频率的恒定性很敏感。于是，相关部门正采取新措施来保证供电的可靠性和质量。如提供附加的电气设备来保证电压和电能其它特性保持恒定。 1、电压调整。长距离传输线存在的电感和电容不容忽视。当电流流过线路时，随着电流的变化，电感和电容会对线路电压产生影响。这样，供电电压会随负荷变化。运行中，有几种设备用来克服这个波动，被称为电压调整。这些设备包括感应调节器、三相同步机（也称同步调相机），它们能够改变传输线路中的电感和电容的有效量。,P1U7A Electric Power Sys

47、tem 第一部分第七单元课文A 电力系统,电感和电容作用能相互抵消。当负载电流感性电抗大于容性电抗时，这种情况总是出现在大型电力系统中，对于给定的电压和电流，传送的功率小于两者相等的时候。这两个量功率之比称为功率因数。由于传输线损耗和电流成比例，如果可能，将在电路中使用电容，这样功率因数尽可能接近于1。正是这个原因，在电力传输系统中，经常使用大型电容器。 2、世界电力生产。从1950年到2003年，最近一年的可用数据显示，每年世界电力生产和消费从小于1万亿千瓦时增长到15.9万亿千瓦时。同样，发电类型也发生了变化。在1950年，世界电力约2/3来自蒸汽源，约1/3 来自水电。2003年，热源生

48、产65%的电能，水电却降至17%，核电占总量的16%。出于安全的考虑，在一些国家，特别是美国，核能的增长缓慢。2003年，美国电能的20%来自核电厂；在世界领先的法国，这个数字是78%。,P1U7A Electric Power System 第一部分第七单元课文A 电力系统,保护 世界上大多数电能的生产来自天然气、煤炭、石油和铀等不可再生资源。煤炭、石油、天然气含有碳元素，它们的燃烧加剧了二氧化碳和其它污染物的排放。科学家们认为，二氧化碳是导致全球变暖，地球表面温度上升的主要因素。 电力用户通过节约用电，如离开房间时关闭电灯等措施消除不必要消耗，可以节省资金，有助于环境保护。其它保护措施包括

49、购买和使用节能电器和灯泡，在费率较低的非用电高峰使用洗衣机和烘干机等电器。消费者也可以考虑环境措施，如购买当地公共部门提供的绿色能源等。绿色能源通常价格较贵，但依靠可再生和环境友好型资源，如风力轮机和地热发电厂。,补充：专业文献翻译的基本方法（二）,1. In other words, mineral substances which are found on earth must be extracted by digging ,boring holes, artificial explosions, or similar operations which make them availab

50、le to us. 换句话说, 通过挖掘、钻孔、人工爆破或相似的作业方式将存在于地壳中的矿物质开采出来，以便于人们利用。 2.The plan is going to be examined first by the research group. 检查组将首先检查这一计划。,被动语态的翻译,翻译成汉语的主动句,七、句子的翻译,7.3 专业文献翻译的基本方法,We remember how air can be made into a liquid. If the liquid is warmed again, it “boils” and turns back into a gas. 我们知

51、道空气怎样可以被制成液体。如果这个液体重新受热，它将会沸腾并且又恢复成气态。, 译成汉语的被动语态,7.3 专业文献翻译的基本方法,七、句子的翻译,被动语态的翻译,Some of these causes are completely reasonable results of social needs .Others are reasonable consequences of particular advances in science being to some extent self-accelerating.,长句的翻译,长句拆译的方法基本上有四种：顺序法、逆序法、分译法和综合法。,

52、顺序法 英语长句结构的顺序与汉语相同，即英语长句中描述的一连串动作是按时间顺序安排的，可采用顺序翻译。,在这些原因中，有些完全是自然而然地来自社会需求，而另一些则是由于科学在一定程度上自我加速而产生特定发展的必然结果。,7.3 专业文献翻译的基本方法,七、句子的翻译,Typically, when a customer places an order, that order begins a mostly paper-based journey from in-basket to in-basket around the company, often being keyed and rekey

53、ed into different departments computer systems along the way.,一般情况下，当一位顾客预定了一份定单后，那张定单就会在公司里被传阅，并经常以这种方式被发送和再转发到不同部门的计算机系统中，,7.3 专业文献翻译的基本方法,七、句子的翻译,顺序法,长句的翻译,Additional social stresses may also occur because of the population explosion or problems arising from mass migration movements.,就是从的后面或中间译起，

54、把长句的开头放在译文的结尾。由于英语和汉语的表达习惯不同：英语习惯于用前置性陈述，先结果后原因；而汉语习惯则相反，一般先原因后结果，层层递进，最后综合。,由于人口的猛增或大量人口的流动造成的种种问题也会对社会造成额外的的压力。,7.3 专业文献翻译的基本方法,七、句子的翻译,逆序法,长句的翻译,Instead of paying someone to manually enter plenty of data into the computer ,you can use a scanner to automatically convert the same information to dig

55、ital files using OCR (Optical Character Recognition )software.,只要在使用扫描仪的过程中借助于光学字符识别软件就可将信息转换成数字文件的形式，从而代替人们手工将大量数据输入到计算机中去的过程。,7.3 专业文献翻译的基本方法,逆序法,七、句子的翻译,长句的翻译,英语长句包含多层意思，而汉语习惯于一个小句表达一层意思，为了使行文简洁，翻译时可把长句中的从句或介词短语分开叙述，顺序基本不变，保持前后的连贯。,7.3 专业文献翻译的基本方法,分译法,七、句子的翻译,长句的翻译,The loads a structure is subjec

56、ted to are divided into dead loads, which include the weights of all the parts of the structure, and live loads, which are due to the weights of people, movable equipment, etc.,一个结构受到的载荷可分为静载和动载两类。静载包括该结构各部分的重量。动载则是由人的重量和可移动设备等的重量而引起的载荷。,有些长句使用以上三种方法都不合适，则可按照时空顺序，夹顺夹逆，主次分明地综合处理。,7.3 专业文献翻译的基本方法,综合法,

57、七、句子的翻译,长句的翻译,Windows 2000 advanced Server includes all the features and application availability of Windows 2000 Server , with additional scalability and reliability features, such as clustering, designed to keep our business-critical applications up and running in the most demanding occasion.,增加了可

58、伸缩性和可靠性（如群集）的Windows 2000高级服务器版包括Windows 2000服务器版的所有特征和应用程序的可用性，它可使以商务为中心正常工作，并在要求最严格的场合下运行。,否定句的翻译,There is much work which can be put into a mathematical form although at first sight it may not appear to have anything to do with arithmetic.,1 全部否定,英语中表示全部否定的词有：no, not, nobody, none, nowhere, neith

59、er , nor 等，这类词译成汉语时一般译为否定句。,7.3 专业文献翻译的基本方法,七、句子的翻译,虽然有很多运算看起来与数学运算毫无关系，但是却可以将它们归为数学形式。,Nothing in the world moves faster than light. 世界上没有什么东西比光速更快了。 There is no sound evidence to prove this. 没有合理的证据可以证明这件事情。 He could not possibly have done the experiment alone. 他不能单独一个人做这件事情。,7.3 专业文献翻译的基本方法,七、句子的翻译,否定句的翻译,1 全部否定,Automatic data processors are in no sense “brain”。,自动数据处理器在某种意义上不是人脑。,Eclipses are not seen in every part of the world. 不是世界上的每一个地方都能看见日蚀。 Not each transistor in the box is out of order. 盒中的晶体管