__电气自动化专业英语lesson02-text03
__电气自动化专业英语lesson01-02
in terms of
adv. 根据, 按照, 用...的话, 在...方面
sufficient [sə'fi∫ənt]
adj. 足够的, 充分的 [古]有能力的, 够资格的, 能胜任的 be sufficient for sb.'s needs 足够满足某人的需要 have not sufficient courage for it 没有做这事的充分勇气 Not sufficient ! 存款不足(略 N/S)。 The pension is not sufficient for living expenses. 这年金不够应付生活费用。
Override [͵əuvə'raid]
vt. 不顾; 使...无效; 藐视; 拒绝 制服; 凌驾; 压倒; 推翻(决议) 践踏 把马骑得过累; 对...驱使过度; 使过量负载 奔越过, 骑马横越 【医】将(断骨)重叠起来 滥用 取而代之 给代理人佣金 凸出, 上升 override one's commission 作越权处置, 滥用职权 The new rule overrides all the previous ones. 新规则使以前的所 有规则失效。
vt.& vi. 区分，区别，辨别 vi. 区别对待 vt. 表明…间的差别，构成…间差别的特 征； [数学] 求…的微分：计算导数或（ 函数的）微分
geometric 英 [ˌdʒi:əˈmetrɪk]美 [ˌdʒiəˈmɛtrɪk]
adj. 几何学的； 成几何级数增减的； 几何装 饰的
We better get going！最好马上就走 ！
电气工程及其自动化专业英语课后翻译
1.2在下面进行的工作中我们要研究的简单电路元件可以根据流过元件的电流与元件两端的电压的关系进行分类。
例如，如果元件两端的电压正比于流过元件的电流，即u ＝ki ，我们就把元件称为电阻器。
其他的类型的简单电路元件的端电压正比于电流对时间的导数或正比于电流关于时间的积分。
还有一些元件的电压完全独立于电流或电流完全独立于电压，这些是独立源。
此外，我们还要定义一些特殊类型的电源，这些电源的电压或电流取决于电路中其他的电流或电压，这样的电源将被称为独立源或受控源。
1.3必须强调的是线性电阻器是一个理想的电路元件；它是物理元件的数学模型。
我们可以很容易地买到或制造电阻器，但很快我们发现这种物理元件只有当电流、电压或者功率处于特定范围时其电压——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。
1.4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。
1.5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。
1.6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。
电气工程及其自动化专业英语第三章课文翻译
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。
电气工程与自动化专业英语翻译(第三章)
晶体管和电子管在大多数电器和电子设备，晶体管几乎完全取代电子管。
晶体管作为电子管执行相同的功能。
但是，它们也有几个重要的优点。
大公较小，从而使更紧凑的产品成为可能。
晶体管也比电子管更坚固耐用。
它通常会提供更好的性能，在一段较长的时间。
最重要的是，晶体管通常需要少得多的电流和电压下正常工作。
这样可以节省能源。
例如，12V汽车收音机使用管吸引约2.5A。
一个类似的晶体管汽车收音机提请只有一小部分的安培。
低功耗晶体管电路的需求尽可能小，重量轻，随身便携产品的工作很长一段时间，小，低小的电池。
各种各样的晶体管最常见的两种类型的晶体管是NPN型晶体管和PNP晶体管。
它们通常被称为双极型晶体管，因为他们的操作取决于被布置为二极管连接在一个“背背”的方式这两种材料的移动。
这样的安排形成三个区域的发射极，基极和集电极。
这些地区被确定由符号E，B，和C。
的一晶体管的区域接合引线或标签，它连接在晶体管电路。
晶体管封装在金属外壳经常有第四铅被称为盾铅的。
将此导线安装在壳体内部，并连接到电路中的一个公共点。
金属外壳的屏蔽层附近晶体管表格的静电和磁场。
符号解释: 有一个方便的方式来记住的符号是否代表了一个结晶体管NPN 或PNP型。
注意代表发射器的箭头指向什么方向。
如果箭头指向相差形成的基，它可以被认为是“不指向N”，因此，该符号代表一个NPN晶体管。
如果箭头指向底座，它可以被认为是的“指向N”。
因此，这个符号代表的P-N-P晶体管。
鉴定: 大多数晶体管标识由一些字母代码，例如2N，然后通过一系列的数字，例如，2N104，2N337，2N556。
其它晶体管都确定了一系列的数字或数字和字母，例如40050，40404，和4D20的组合。
晶体上手册: 设备是否是NPN或PNP型的晶体管的识别码不表示。
晶体管手册或规格表中发现这样的技术数据。
这些手册也给各种不同的电路中使用的晶体管的信息。
晶体管外形图提供了详细的信息，它们的大小，形状和连接。
电气自动化专业英语1,2,3,5,8,13章翻译
第一章电子测量仪表电子技术人员使用许多不同类型的测量仪器。
一些工作需要精确测量面另一些工作只需粗略估计。
有些仪器被使用仅仅是确定线路是否完整。
最常用的测量测试仪表有：电压测试仪，电压表，欧姆表，连续性测试仪，兆欧表，瓦特表还有瓦特小时表。
所有测量电值的表基本上都是电流表。
他们测量或是比较通过他们的电流值。
这些仪表可以被校准并且设计了不同的量程，以便读出期望的数值。
1．1安全预防仪表的正确连接对于使用者的安全预防和仪表的正确维护是非常重要的。
仪表的结构和操作的基本知识能帮助使用者按安全工作程序来对他们正确连接和维护。
许多仪表被设计的只能用于直流或只能用于交流，而其它的则可交替使用。
注意：每种仪表只能用来测量符合设计要求的电流类型。
如果用在不正确的电流类型中可能对仪表有危险并且可能对使用者引起伤害。
许多仪表被设计成只能测量很低的数值，还有些能测量非常大的数值。
警告：仪表不允许超过它的额定最大值。
不允许被测的实际数值超过仪表最大允许值的要求再强调也不过分。
超过最大值对指针有伤害，有害于正确校准，并且在某种情况下能引起仪表爆炸造成对作用者的伤害。
许多仪表装备了过载保护。
然而，通常情况下电流大于仪表设计的限定仍然是危险的。
1．2基本仪表的结构和操作许多仪表是根据电磁相互作用的原理动作的。
这种相互作用是通过流过导体的电流引起的（导体放置在永久磁铁的磁极之间）。
这种类型的仪表专门适合于直流电。
不管什么时候电流流过导体，磁力总会围绕导体形成。
磁力是由在永久磁铁力的作用下起反应的电流引起。
这就引起指针的移动。
导体可以制成线圈，放置在永久磁铁磁极之间的枢钮（pivot中心）上。
线圈通过两个螺旋型弹簧连在仪器的端子上。
这些弹簧提供了与偏差成正比的恢复力。
当没有电流通过时，弹簧使指针回复到零。
表的量程被设计来指明被测量的电流值。
线圈的移动（或者是指针的偏移）与线圈的电流值成正比。
如果必须要测量一个大于线圈能安全负载的电流，仪表要包含旁路或者分流器。
电气工程及其自动化专业英语答案第三章
电气工程及其自动化专业英语答案第三章
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电气工程及其自动化专业英语翻译（精选多篇）
电气工程及其自动化专业英语翻译（精选多篇）第一篇：电气工程及其自动化专业英语翻译Electric Power Systems.The modern society depends on the electricity supply more heavily than ever before.It can not be imagined what the world should be if the electricity supply were interrupted all over the world.Electric power systems(or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world.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.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..Within a few years similar systems were in operation in most large cities throughout the world.With the development of motors by Frank Sprague in 1884, motor loads were added to such systems.This was the beginning of what would develop into one of the largest industries in the world.In spite of the initial widespread use of DC systems, they were almost completely superseded by AC systems.By 1886, the limitations of DC systems were becoming increasingly apparent.They could deliver power only a short distance from generators.To keep transmission power losses(I 2 R)and voltage drops to acceptable levels, voltage levels had to be high for long-distance power transmission.Such high voltages were not acceptable for generation and consumption of power;therefore, a convenient means for voltage transformationbecame a necessity.The development of the transformer and AC transmission by L.Gaulard and JD Gibbs of Paris, France, led to AC electric power systems.In 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and Portland.It was a single-phase line transmitting power at 4,000 V over a distance of 21 km.With the development of polyphase systems by Nikola Tesla, the AC system became even more attractive.By 1888, Tesla held several patents on AC motors, generators, transformers, and transmission systems.Westinghouse bought the patents to these early inventions, and they formed the basis of the present-day AC systems.In the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or AC.By the turn of the century, the AC system had won out over the DC system for the following reasons:（1）Voltage levels can be easily transformed in AC systems, thusproviding the flexibility for use of different voltages for generation, transmission, and consumption.（2）AC generators are much simpler than DC generators.（3）AC motors are much simpler and cheaper than DC motors.The first three-phase line in North America went into operation in 1893——a 2,300 V, 12 km line in southern California.In the early period of AC power transmission, frequency was not standardized.This poses a problem for interconnection.Eventually 60 Hz was adopted as standard in North America, although 50 Hz was used in many other countries.The increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage levels.To avoid the proliferation of anunlimited number of voltages, the industry has standardized voltage levels.In USA, the standards are 115, 138, 161, and 230 kV for the high voltage(HV)class, and 345, 500 and 765 kV for the extra-high voltage(EHV)class.In China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330(only in Northwest China)and500 kVforEHVclass.Thefirst750kVtransmission line will be built in the near future in Northwest China.With the development of the AC/DC converting equipment, high voltage DC(HVDC)transmission systems have become more attractive and economical in special situations.The HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are different.The basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and frequency.Because electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done simultaneously.A fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the customers.Therefore, a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount importance.Power system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance..Instability in a power system may be manifested in many different ways depending on the system configurationand operating mode.Traditionally, the stability problem has been one of maintaining synchronous operation.Since power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially “in step”.This asp ect of stability is influenced by the dynamics of generator rotor angles and power-angle relationships, and then referred to “ rotor angle stability ”译文：电力系统现代社会比以往任何时候更多地依赖于电力供应。
电气工程及其自动化专业英语第三章section_3-2
Section 2 The DC-DC Converters
Text New Words and Expressions Transition of part of speech Exercises End
Section 2 The DC-DC Converters
Section 2 The DC-DC Converters
If the duty ratio D is made a linear function of uC, a control voltage
D = ku C
U o = (kU S )u C
(3-6)
The output voltage is then a linear function of the control voltage. This is also the principle of switchmode linear amplifier. The gain of this amplifier is determined by the input dc source voltage. Neglecting the power losses in the circuit elements, we could use the equation of the balance of power
Section 2 The DC-DC Converters
US I S = Uo Io
− −
(3-7)
where IS is the average current from the DC source. Hence,
Io
−
=
电气工程及其自动化专业英语
电气工程及其自动化专业英语Section I basic electric circuitChapter 1 Introduction to electric circuitsNew Words and Expressions1. electrical circuit n. 电路2. voltage n. 电压，伏特3. curre nt n. 电流，通用的，流通的，现在的4. curre nt flow n. 电流5. resistor n. 电阻，电阻器6. battery n. 电池7. load n. 负载，负荷8. performa nee n. 性能9. circuit diagram n. 电路图10. idealized model n. 理想模型Introduction*A simple circuit and its components.idealized model of the circuit*Model can be cha nged if n ecessary.*summarizeIn elementary physics classes you undoubtedly have been introduced to the fun dame ntal con cepts of electricity and how real comp onen ts can be put together to form an electrical circuit. A very simple circuit, for example, might consist of a battery, some wire, a switch, and an incandescent light bulb as shown in Fig.1-1. The battery supplies the en ergy required to force electro ns around the loop, heati ng the filame nt of the bulb and caus ing the bulb to radiate a lot of heat and some light.Energy is transferred from a source, the battery, to a load, the bulb———You probably already know that the voltage of the battery and the electrical resista nee of the bulb have something to do with the amount of curre nt that will flowin the circuit. From your own practical experienee you also know that no current will flow until the switch is closed. That is, for a circuit to do anything, the loop has to be completed so that electro ns can flow from the battery to the bulb and the n back aga in to the battery. And fin ally, you probably realize that it doesn t much matter, whether there is on e foot or two feet of wire connecting the battery to the bulb, but that it probably would matter if there is a mile of wire between it and the bulb.Also shown in Fig. 1-1 is a model made up of idealized components. The batteryis modeled as an ideal source that puts out a constant voltage, VB, no matter what amount of curre nt, i, is draw n. The wires are con sidered to be perfect con ductors that offer no resista nee to curre nt flow. The switch is assumed to be ope n or closed. There is no arcing of curre nt across the gap whe n the switch is ope ned, nor is there any bounce to the switch as it makes con tact on closure. The light bulb is modeled as a simple resistor, R, that never changes its value, no matter how hot it becomes or how much curre nt is flow ing through it.Fig. 1-1 (a) A simple circuit(b) An idealized represe ntati on of thecircuitFor most purposes, the idealized model shown in Fig. 1-1b is an adequate represe ntati on of the circuit; that is, our prediction of the current that will flow through the bulb whenever the switch is closed will be sufficiently accurate that we can consider the problem solved. There may be times, however, when the model is in adequate. The battery voltage, for example, may drop as more and more curre nt is drawn, or as the battery ages. --------------------------------- T he light bulb' s resistance may change as it heats up, and the filame nt may have a bit of inductance and capacitance associated with it as well as resistance so that when the switch is closed, the current may not jump in sta ntan eously from zero to some fin al, steady state value. The wires may beundersized, and some of the power delivered by the battery may be lost in the wires before it reaches the load. These subtle effects may or may not be important, depending on what we are trying to find out and how accurately we must be able to predict the performa nee of the circuit. If we decide they are importa nt, we can always cha nge the model as n ecessary and then proceed with the an alysis. The point here is simple. The comb in ati ons of resistors, capacitors, in ductors, voltage sources, curre nt sources, and so forth, that you see in a circuit diagram are merely models of real comp onents that comprise a real circuit, and a certa in amount of judgme nt is required to decide how complicated the model must be before sufficie ntly accurate results can be obta in ed. For our purposes, we will be using very simple models in general, leav ing many of the complicati ons to more adva need textbooks.Chapter 2Definitions of key electrical quantitiesNew Words and Expressionscharge n. vt.电荷；充电nu cleus n.原子核(pl.); nuclear adj.n egative n.否定，负数，底片adj.否定的，消极的，负的，阴性的positive adj.［数］正的adj.［电］阳的in gen eral 通常,大体上，一般而言，总的说来algebraic adj.代数的，关于代数学的soluti on to the circuit problem n.关于电路问题的解法the un its of power n.功率的单位direct curre nt (dc) n 直流电alter nat ing curre nt(ac) n.交流电sinu soidally adv.正弦地tran sistor n.晶体管Part 1 Charge and CurrentAn atom con sists of a positively charged nu cleus surro un ded by a swarm of n egativelycharged electr ons. The charge associated with one electr on has bee n found to be 1.602 x 10- 19 coulombs; or, stated the other way around, one coulomb can be defined as the charge on 6.242 x 1018 electro ns. While most of the electr ons associated with an atom are tightly bound to the nu cleus, good con ductors, like copper, have free electrons that are sufficie ntly dista nt from their nu clei that their attract ion to any particular n ucleus is easily overcome. These con ducti on electr ons are free to wan der from atom to atom, and their moveme nt con stitutes an electric curre nt.In a wire, when one coulomb ' s worth of charge passes a given spot in one second, the current is defined to be one ampere (abbreviated A), named after the nineteenth-century physicist Andr ' e Marie Amp'ere. That is, curre nt i is the net rate of flow of charge q past a point, or through an area:i=d q/d t (1.1)In general, charges can be negative or positive. For example, in a neon light, positive ions move in one direct ion and n egative electr ons move in the other. Each con tributes to curre nt, and the total curre nt is their sum. By conven ti on, the direct ion of curre nt flow is take n to be the direct ion that positive charges would move, whether or not positive charges happen to be in the picture. Thus, in a wire, electrons moving to the right constitute a current that flows to the left, as shown in Fig.1-2.(〉)dq--- / =—dtFig. 1-2 By conven tio n, n egative charges movi ng in one direct ion con stitute a positive curre ntflow in the opposite direct ionW/hen charge flows at a steady rate in one direction only, the current is said to be direct current, or 血A battery, for example, supplies direct curre nt. When charge flows back and forth sinusoidally, it is said to be alternating current, or ac. In the United States the ac electricity delivered by tes of ac and dc are show n in Fig.1-3.Time ―(a)Fig. 1-3 (a) Steady-state direct curre nt (de) (b) Alter nat ing curre nt(ac)Part 2 Kirchhoff' s Current LawTwo of the most fun dame ntal properties of circuits were established experime ntally a cen tury and a half ago by a Germa n professor, Gustav Robert Kirchhoff (1824 - 1887). The first property, known as Kirchhoff ' s current law (abbreviated KCL), states that at every instant of time the sum of the curre nts flow ing into any node of a circuit must equal the sum of the curre nts leavi ng the no de, where a node is any spot where two or more wires are join ed. This is a very simple, but powerful con cept. It is in tuitively obvious once you assert that curre nt is the flow of charge, and that charge is con servative—n either being created nor destroyed as it en ters a no de. Uni ess charge somehow builds up at a no de, which it does not, the n the rate at which charge en ters a node must equal the rate at which charge leaves the no de.There are several alter native ways to state Kirchhoff ' s curre nt law. The most com monly used stateme nt says that the sum of the curre nts flow ing into a node is zero as show n in Fig. 1-4a, in which case some of those curre nts must have n egative values while some have positive values. Equally valid would be the stateme nt that the sum of the curre nts leav ing a node must be zero as show n in Fig. 1-4b(aga in some of these curre nts n eed to have positive values and some n egative). Fin ally, we could say that the sum of the curre nts en teri ng a node equals the sum of the curre nts leav ing a node (Fig. 1-4c). These are all equivale nt as long as we un dersta nd what is meant about the directi on of curre nt flow whe n we in dicate it with an arrow on a circuit diagram. Curre nt that actually flows in the directi on show n by the arrow is give n a positive sig n. Curre nts that actuallyflow in the opposite direct ion have n egative values.(a) The sum of the curre nts into a node equals zero(b) The sum of the curre nts leav ing the node is zero(c) The sum of the curre nts en teri ng a node equals the sum of the curre nts leavi ng the node Note that you can draw curre nt arrows in any directio n that you want — that much is arbitrary — but once havi ng draw n the arrows, you must the n write Kirchhoff ' s curre nt law in a manner that is con siste nt with your arrows, as has bee n done in Fig.1-4. The algebraic soluti on to the circuit problem will automatically determ ine whether or not your arbitrarily determ ined direct ions for curre nts were correct.Example 1.1 Using Kirchhoff ' s Current LawA node of a circuit is shown with current direction arrows chosen arbitrarily. Havingpicked those directi on s, i1 = - 5 A, i2 = 3 A, and i3 = - 1 A. Write an expressi on for Kirchhoff ' s current law and solve for i4.Solution. By Kirchhoff ' s current law,i1 + i2 = i3 + i4 so thatThat is, i4is actually 1 A flowi ng into the no de. Note that i2, i3, and i4 are all en teri ng the no de, and i1 is the only curre nt that is leavi ng the no de.Part 3 Kirchhoff ' s Voltage LawElectr ons won ' t flow through a circuit uni ess they are give n some en ergy to help send them on their way. That “ push ” is measured in volts, where voltage is defi ned to be the amount nodenodenode1 + i4 i4 = - 1 AFig. 1-4 lllustrating various ways that Kirchhoff ' s current law can be statedof en ergy (w, joules) give n to a un it of charge,v=dw/dq A 12-V battery therefore gives 12 joules of en ergy to each coulomb of charge that it stores. Note that the charge does not actually have to move for voltage to have meaning. Voltage describes the potential for charge to do work.While curre nts are measured through a circuit comp onent, voltages are measured across componen ts. Thus, for example, it is correct to say that curre nt through a battery is 10 A, while the voltage across that battery is 12 V. Other ways to describe the voltage across a comp onent in clude whether the voltage rises across the comp onent or drops. Thus, for example, for the simple circuit in Fig. 1-1, there is a voltage rise across the battery and voltage drop across the light bulb. Voltages are always measured with respect to someth ing. That is, the voltage of the positive terminal of the battery is“ so many volts ” with respect to the negative terminal; or, the voltage at a point in a circuit is some amount with respect to some other poin t. In Fig. 1-5, curre nt through a resistor results in a voltage drop from point A to point B of VAB volts. V A and VB arethe voltages at each end of the resistor, measured with respect to some other point.The reference point for voltages in a circuit is usually desig nated with a ground symbol. While many circuits are actually groun ded — that is, there is a path for curre nt to flow directly into the earth —some are not (such as the battery, wires, switch, and bulb in a flashlight). When a ground symbol is show n on a circuit diagram, you should con sider it to be merely a reference point at which thevoltage is defi ned to be zero. Fig.1-6 points out how cha nging the node labeled as ground cha nges the voltages at each node in the circuit, but does not cha nge the voltage drop across each comp onent.(1-2)Fig. 1-5 The voltage drop from point A to point B is V AB, where VAB = VA - VBThe sec ond of Kirchhoff ' s fun dame ntal laws states that the sum of the voltages around any loop of a circuit at any instant is zero. This is known as Kirchhoff ' s voltage law (KVL). Just as was the case for Kirchhoff ' s curre nt law, there are alter native, but equivale nt, ways of stat ing KVL. We can, for example, say that the sum of the voltage rises in any loop equals the sum of the voltagedrops around the loop. Thus in Fig. 1-6, there is a voltage rise of 12 V across the battery and avoltage drop of 3 V across R1 and a drop of 9 V across R2. ------------- Notice that it doesn' t matterwhich node was labeled ground for this to be true. Just as was the case with Kirchhoff ' s current law, we must be careful about labeli ng and in terpret ing the sig ns of voltages in a circuit diagram in order to write the proper vers ion of KVL. A plus (+) sig n on a circuit comp onent in dicates a reference direct ion un der the assumpti on that the pote ntial at that end of the comp onent is higher than the voltage at the other end. Aga in, as long as we are con siste nt in writi ng Kirchhoff ' s voltage law, the algebraic soluti on for the circuit will automatically take care of sig ns.Part 5 Summary of Principal Electrical QuantitiesThe key electrical qua ntities already in troduced and the releva nt relati on ships betwee n these quantities are summarized in Table 1-1.Since electrical quantities vary over such a large range of magnitudes, you will often find yourself work ing with very small qua ntities or very large qua ntities. For example, the voltage created by your TV antenna may be measured in millionths of a volt (microvolts, 卩V), while the power gen erated by a large power stati on may be measured in billi ons of watts, or gigawatts (GW). To describe quantities that may take on such extreme values, it is useful to have a system of prefixes that accompany the units. The most commonly used prefixes in electrical engineering are give n in Table 1-2.Part 6 Ideal Voltage Source and Ideal Current SourceElectric circuits are made up of a relatively small nu mber of differe nt kinds of circuiteleme nts, or comp onen ts, which can be in terc onn ected in an extraord in arily large nu mber of ways.At this point in our discussion, we will concentrate on idealized characteristics of these circuit eleme nts, realiz ing that real comp onents resemble, but do not exactly duplicate, the characteristics that we describe here.An ideal voltage source is one that provides a give n, known voltage vs, no matter what sort ofload it is conn ected to. That is, regardless of the curre nt draw n from the ideal voltage source, it will always provide the same voltage. Note that an ideal voltage source does not have to deliver a con sta nt voltage; for example, it may produce a sinu soidally vary ing voltage —the key is that voltage is not a fun ctio n of the amount of curre nt draw n. A symbol for an ideal voltage source is show n in Fig. 1-7.A special case of an ideal voltage source is an ideal battery that provides a con sta nt dc output, as show n in Fig. 1-8. A real battery approximates the ideal source; but as curre nt in creases, the output drops somewhat. To acco unt for that drop, quite ofte n the model used for a real battery is an ideal voltage source in series with the internal resista nee of the battery.An ideal curre nt source produces a give n amount of curre nt is no matter what load it sees. As show n in Fig. 1-9, a commo nly used symbol for such a device is circle with an arrow in dicati ng the directi on of curre nt flow. While a battery is a good approximati on to an ideal voltage source, there is nothing quite so familiar that approximates an ideal curre nt source. Some tran sistor circuits come close to this ideal and are ofte n modeled with idealized curre nt sources.Section II The electric power systemChapter 1 Brief Introduction to The Electric Power SystemNew Words and ExpressionsMinimum a 最小prime mover n 原动机gen erator n 发电机load n 负载furn ace n 炉膛boiler n 锅炉fissi on able n 可裂变的fissi on able material 核燃料Part 1 Minimum Power systemelevatio n n 高度，海拔internal combusti on engine 内燃机 steam-drive n turbi ne 汽轮机hydraulic turbi ne 水轮机convert v 变换，转换 shaft n 传动轴，轴 torquen 力矩servomecha nism n 伺服机构* Elements of a minimum electric power system *Types of energy source *Types of prime mover *Types of electrical load*Functions of the control systemA minimum electric power system is shown in Fig.1-1, the system consists of an energy source, a prime mover, a generator, and a load.The en ergy source may be coal, gas, or oil burned in a furnace to heat water and gen erate steam in a boiler; it may be fissi on able material which, in a nu clear reactor, will heat water to produce steam; it may be water in a pond at an elevatio n above the gen erat ing stati on; or it may be oil or gas burned in an internal combusti on engine.The prime mover may be a steam-driven turbine, a hydraulic turbine or water wheel, or aninternal combustion engine. Each one of these prime movers has the ability to convert energy in the form of heat, falling water, or fuel into rotation of a shaft, which in turn will drive theEnergy source Prime nioverGenerator Lx>adContjolFig* 1-1 The tninfnmm electric power systemgen erator.The electrical load on the gen erator may be lights, motors, heaters, or other devices, alone or in comb in ati on. Probably the load will vary from mi nute to min ute as differe nt dema nds occur. The control system functions (are ) to keep the speed of the machines substantially constant and the voltage within prescribed limits, even though the load may cha nge. To meet these load con diti on s, it is n ecessary for fuel in put to cha nge, for the prime mover in put to vary, and for the torque on the shaft from the prime mover to cha nge in order that the gen erator may be kept at con sta nt speed. In additi on, the field curre nt to the gen erator must be adjusted to maintain con sta nt output voltage. The con trol system may in clude a man stati oned in the power pla nt who watches a set of meters on the gen erator output term in als and makes the n ecessary adjustme nts manu ally .In a moder n stati on, the con trol system is a servomecha nism that sen ses gen erator-output con diti ons and automatically makes the n ecessary cha nges in en ergy in put and field curre nt to hold the electrical output with in certa in specificati ons.Part 2 More Complicated Systems*Foreword*Cases of power system with out circuit breaker *Power system with circuit breakerNew Words and Expressions1. associated2. circuit3. circuit breaker4. dee nergize5. dee nergized6. outage n7. diagram8. switch out of9. switch offIn most situati ons the load is not directly conn ected to the gen erator term in als. More com monlya 联接的 n 电路n 断路器 vt 切断，断电 adj 不带电的停电 n 简图退出来，断开 v 切断，关闭the load is some distanee from the generator, requiring a power line connecting them. It is desirable to keep the electric power supply at the load with in specificati ons. However, the con trols are near the generator, which may be in another building, perhaps several miles away.If the dista nce from the gen erator to the load is con siderable, it may be desirable to in stall transformers at the generator and at the load end, and to transmit the power over a high-voltage line (Fig.1-2). For the same power, the higher-voltage line carries less current, has lower losses for the same wire size, and provides more stable voltage., TransformerTransformerPrime 〔Mover Generator f C High-voltage line—Fig- 1-2 A generator connected through transformers anda high-voltage line to a distant loadIn some cases an overhead line may be un acceptable. In stead it may be adva ntageous to use an un dergro und cable. With the power systems talked above, the power supply to the load must be in terrupted if, for any reas on, any comp onent of the system must be moved from service for maintenance or repair.Additi onal system load may require more power tha n the gen erator can supply. Ano ther gen erator with its associated tran sformers and high-voltage line might be added.It can be shown that there are some advantages in making ties between the generators (1) and at the end of the high-voltage lines (2 and 3), as shown in Fig.1-3. This system will operate satisfactorily as long as no trouble develops or no equipment needs to be taken out of service.Kig. 1-3 A system with para)lei operation or the generators t of the transformers andof the transmission lintsThe above system may be vastly improved by the in troducti on of circuit breakers, which may be ope ned and closed as n eeded. Circuit breakers added to the system, Fig.1-4, permit selected piece of equipme nt to switch out of service without disturb ing the rema in der of system. With this arran geme nt any eleme nt of the system may be dee nergized for maintenance or repair by operati on of circuit breakers. Of course, if any piece of equipme nt is take n out of service, the n the total load must be carried by the remaining equipment. Attention must be given to avoid overloads duri ng such circumsta nces. If possible, outages of equipme nt are scheduled at times when load requireme nts are below no rmal.Low-voltageo=^GeneratorsFig.1-5 shows a system in which three gen erators and three loads are tied together by threeFig* 1-4 A system with necessary circuit breakerstran smissi on lin es. No circuit breakers are show n in this diagram, although many would berequired in such a system.Fis- 1-S Three generators supplying threeloads over hlgh-voltnge trAnsmlsston linesChapter 2 Faults on Power SystemNew Words and Expressions1. fault2. in terfere neen 干扰，防碍6. feed (fed)给。
电气自动化专业英语 翻译 中文译文
电气自动化专业英语（翻译1-3）第一部分：电子技术第一章电子测量仪表电子技术人员使用许多不同类型的测量仪器。
一些工作需要精确测量面另一些工作只需粗略估计。
有些仪器被使用仅仅是确定线路是否完整。
最常用的测量测试仪表有：电压测试仪，电压表，欧姆表，连续性测试仪，兆欧表，瓦特表还有瓦特小时表。
所有测量电值的表基本上都是电流表。
他们测量或是比较通过他们的电流值。
这些仪表可以被校准并且设计了不同的量程，以便读出期望的数值。
1．1安全预防仪表的正确连接对于使用者的安全预防和仪表的正确维护是非常重要的。
仪表的结构和操作的基本知识能帮助使用者按安全工作程序来对他们正确连接和维护。
许多仪表被设计的只能用于直流或只能用于交流，而其它的则可交替使用。
注意：每种仪表只能用来测量符合设计要求的电流类型。
如果用在不正确的电流类型中可能对仪表有危险并且可能对使用者引起伤害。
许多仪表被设计成只能测量很低的数值，还有些能测量非常大的数值。
警告：仪表不允许超过它的额定最大值。
不允许被测的实际数值超过仪表最大允许值的要求再强调也不过分。
超过最大值对指针有伤害，有害于正确校准，并且在某种情况下能引起仪表爆炸造成对作用者的伤害。
许多仪表装备了过载保护。
然而，通常情况下电流大于仪表设计的限定仍然是危险的。
1．2基本仪表的结构和操作许多仪表是根据电磁相互作用的原理动作的。
这种相互作用是通过流过导体的电流引起的（导体放置在永久磁铁的磁极之间）。
这种类型的仪表专门适合于直流电。
不管什么时候电流流过导体，磁力总会围绕导体形成。
磁力是由在永久磁铁力的作用下起反应的电流引起。
这就引起指针的移动。
导体可以制成线圈，放置在永久磁铁磁极之间的枢钮（pivot中心）上。
线圈通过两个螺旋型弹簧连在仪器的端子上。
这些弹簧提供了与偏差成正比的恢复力。
当没有电流通过时，弹簧使指针回复到零。
表的量程被设计来指明被测量的电流值。
线圈的移动（或者是指针的偏移）与线圈的电流值成正比。