专业英语翻译(中英对照).doc

1. Electrical Measuring Instruments电子测量仪表Electrical personnel use many different types of measuring instruments. 电子技术人员使用许多不同类型的测量仪器。Some jobs require very accurate measurements while other jobs need only rough estimates. 一些工作需要精确测量面另一些工作只需粗略估计。Some instruments are used solely to determine whether or not a circuit is complete. 有些仪器被使用仅仅是确定线路是否完整。The most common measuring and testing instruments are voltage testers, voltmeters, ammeters, ohmmeters, continuity testers, megohmmeters, wattmeters（功率计）, and watt-hour meters（电度表，电表）。 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。All meters used for measuring electrical values are basically current meters. 所有测量电值的表基本上都是电流表。They measure or compare the values of current flowing through them. 他们测量或是比较通过他们的电流值。The meters are calibrated and the scale is designed to read the value of the desired unit. 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 SAFETY PRECAUTION安全预防Correct meter connections are very important for the safety precaution of the user and for proper maintenance of the meters. 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。A basic knowledge of the construction and operation of meters will aid the user in making proper connections and maintaining them in safe working order. 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。Many instruments are designed to be used on DC or AC only, while others can be used interchangeably. 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。Note: It is very important to use each meter only with the type of current for which the meter is designed. 注意：每种仪表只能用来测量符合设计要求的电流类型。Using a meter with an incorrect type of current can result in damage to the meter and may cause injury to the user. 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。Some meters are constructed to measure very low values. 许多仪表被设计成只能测量很低的数值Other meters can measure extremely high values.还有些能测量非常大的数值。CAUTION: Never allow a meter to exceed its rated maximum limit. 警告：仪表不允许超过它的额定最大值。The importance of never allowing the actual value to exceed the maximum value indicated on the meter can not be overemphasized. 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。Exceeding maximum values can damage the indicating needle, interfere with proper calibration, and in some instances may cause the meter to explode, resulting in injury to the user. 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。Some meters are equipped with over correct protection. However, a current many times greater than the instruments design limit may still be hazardous. 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。2. Fundamentals of Solid-state Power Device固体功率器件的基本原理In this chapter we focus on solid-state power devices, or power semiconductors, only as they are being used in the power leads or power circuits to three-phase 460 V AC squirrel cage induction motors for either phase (voltage) control or frequency (speed) control. 本章将集中讨论固态功率器件或功率半导体器件，并且只研究它们在采用相控（电压控制）或频率控制（速度控制）的三相交流鼠笼式感应电机的功率电路中的应用。 2.2 SOLID-STATE POWER DEVICES固态功率器件The five major types of power semiconductors used in solid-state AC motor control are: 有五种用于固体交流电机控制中的功率元器件：Diodes二极管Thyristorse.g., silicon-controlled rectifiers (SCRs) 晶闸管（例如：可控硅整流器SCR）Transistors电子晶体管Gate-turn-off thyristors门极可关断晶闸管（GTO）Triacs 双向可控硅SCRs and triacs are commonly used for phase controls. 晶闸管SCR和双向可控硅一般用于相位控制（相控）。Various combinations of diodes, SCRs, transistors, and GTOs are used for speed controls. 各种二极管，晶闸管SCR，电子晶体管，门极可关断晶闸管的联合体用于频控。The commonality of these devices is the use of crystals of silicon in the form of wafers that are layered so as to form various combinations of PN junction. 这些器件的共性是：利用硅晶体形成的薄片构成P-N结的各种组合。The P junction is usually called the anode and N junction is usually called the cathode for diodes, SCRs, and GTOs; the corresponding terms for transistors are collector and emitter. 对二极管，SCR， GTO一般P结叫正极N结叫负极；相应的电子晶体管叫集电极和发射极。The differences among these devices relate to how they go into and out of conduction and in their available ampere and voltage capabilities. 这些器件的区别在于导通和关断的方法及电流和电压的容量。 Lets take a brief look at each of these devices in terms of these parameters. 让我们根据他们的参数简单看一下这些元器件。3 Analog Electronics模拟电子3.1 INTRODUCTION介绍3.1.1 The Contrast between Analog and Digital Electronics模拟和数字电子学对照We have already explored how transistors and diodes are used as switching devices to process information which is represented in digital form. 我们已经研究过三极管和二极管怎样作为开关器件用于处理以数字形式出现的信息。Digital electronics uses transistors as electrically controlled switches: transistors are either saturated or cut off. 数字电子学中，三极管用作电子控制开关：它不是饱和就是截止。The active region is used only in transition from one state to he other.（三极管的）动态区域仅用于从一种状态过渡到另一种状态。By contrast, analog electronics depends on the active region of transistors and other types of amplifiers. 与之相对的是，模拟电子学依赖于三极管的动态区域和其它放大器的形式。The Greek roots of “analog” mean “in due ratio”, signifying in this usage that information is encoded into an electrical signal which is proportional to the quantity being represented. 希腊语词根“analog”的意思是“以一定的比例”，在这里表示信息被编码成为与表达量成正比的电信号。In Fig.3.1 our information is some sort of music, originating physically in the excitation and resonances of a musical instrument. 在图3.1中，我们的信息是某种音乐，物理上由乐器的激励和共鸣产生。The radiated sound consists in the ordered movement of air molecules and is best understood ad acoustic waves. 辐射的声波由空气分子的有序运动组成，准确的理解为声波， These produce motion in the diaphragm of a microphone, which in turn produces an electrical signal. 它使话筒的振动膜移动，依次产生电信号。The variation in the electrical signal are a proportional representation of the sound waves. 电信号的变化与声波成比例。The electrical signal is amplified electronically, with an increase in signal power occurring at the expense of the input AC power to the amplifier. 电信号被用电子的方法放大，即利用输入放大器的交流电能将信号的功率放大。The amplifier output drives a recording head and produces a wavy groove on a disk. 放大器的输出驱动一个记录头，并且在一个圆盘上产生起伏的沟槽。If the entire system is good, every acoustic variation of the air will be recorded on the disk and, when the record is played back through a similar system and the signal reradiated ad sound energy be a loudspeaker, the resulting sound should faithfully reproduce the original music. 如果整个系统正常，每一次声波振动都会记录在圆盘上，并且当该记录通过类似的系统重放，信号以声能的形式从扬声器辐射出来，所产生的声音能忠实地重现原始音乐。Electronic systems based on analog principles form an important class of electronic devices. 基于模拟原理的电子系统形成了一类重要的电子仪器。Radio and TV broadcasting are common examples of analog systems, as are many electrical instruments used in monitoring deflection (strain gages, for example), motion (tachometers), and temperature (thermocouples). 收音机和电视机的播放是模拟系统的典型例子，许多仪器也是模拟系统，它们的应用领域包括偏差检测（应变计量器）运动控制（测速仪）和温度测量（热电偶）。Many electrical instruments-voltmeters, ohmmeters, ammeters, and oscilloscopes-utilize analog techniques, at least in part. 许多电子仪器电压表、电流计欧姆表、和示波器应用或至少是部分应用了模拟技术。Analog computers existed before digital computers were developed. 模拟计算机在数字计算机成熟之前就已存在。In an analog computer, the unknowns in a differential equation are modeled with electrical signals. 在模拟计算中，用电信号模拟微分方程的未知量。Such signals are integrated, scaled, and summed electrically to yield solutions with modes effort compared with analytical or numerical techniques. 用电子的方法对这些信号积分、比例运算和求和以获得方程的解，比起解析或数值求解方法要容易一些。4.1.1 What is a Digital Signal什么是数字信号 A Historical Example. 一个历史例子“Listen my children and you shall hear of the midnight ride of Paul Revere”听，我的孩子们，你们将会听到保罗瑞维尔午夜策马飞奔的传奇，According to Longfellows poem, Paul Revere was sent riding through the New England countryside by a signal from the bell tower of the Old North Church in Boston. 根据朗费罗的诗，保罗瑞维尔通过波士顿老北教堂的钟楼那里给新英格兰农民发信号。（不写：如果英军今晚无论是从陆地还是从海上来犯，在老北教堂钟楼的拱门上高挂一盏灯笼作为信号） “One if by land and two if by sea.”。一盏灯笼表示从陆地来，两盏灯笼表示从海上来。That is, one light was to be displayed if the Britishforces were advancing toward Concord by the road from Boston, and two lightswere to be displayed if they were crossing the Mystic River to take an indirectroute)那就是说， 如果英国军队从波士顿陆地向康科德前进，展示一盏灯，如果他们穿过Mystic河走间接航线，两盏灯将被展示。The message received by the Patriot was coded in digital form. 爱国者们收到的消息就是数字形式的编码。We would say today that the two“bits”of information were conveyed by the code(strictly speaking, two bits could indicate four possible message and would require distinguishable lights, say one red and one white). 我们今天将说这两个位的信息通过代码运传送(严格地说， 二位能表明4个可能消息，并且要求可分辨的灯，一个红灯和一个白色的灯) .The first light signaled that the British were advancing. 第一个灯光通知英国军队正前进，The second light indicated by what route they were coming. 第2盏灯指示他们通过什么路线来。Because only two routes ofadvance were envisioned, this second bit of information could be interpreted asindicating one of the two routes. 因为想象只有两条路，信息的第二位能被解释为表明两条路线之一。Information can be communicate in digital form if the massage is capable of being defined by a series of yes/no statements. 如果信息能被一系列的YES/NO所定义，信息就能以数字形式确定。There can be only two states of each variable used in conveying the information. 每个变量只可能有两种状态在传送信息方面使用。 Reducing information to a series of yes/no statements might appear to be a severe limitation on this method, but the method is in fact quite powerful. 这种方法把信息简化为一系列是/不看起来有局限性，但是这种方法实际上十分有用。 Numbers can be represented in base 2 and the alphabet by a digital code. 数目可以以基数2表示，字母表可以表示成数字代码。Indeed, any situation with a finite number of outcomes can be reduced to a digital code. 的确，有限输出的任何情形都可以被简化成数字代码。 Specifically, n digital bits can represent 2n states of possible outcomes. 具体的，n位数字能描述成2n个可能状态。 Digital communication takes a well-defined code known to the parties at both ends, as in our historical example. 如同在我们的历史例子中，数字通讯能用明确定义的代码在两种情况下都通知到大家。Analysis of the Revere Communication Code. 瑞维尔通讯码分析。In order to fix further the idea of digital information, we shall define two digital variables which describe the Paul Revere communication system, Let B describe whether the British are coming, and L describe the route by which they are coming, provide that they are coming. 为了更进一步确定数字的信息的概念， 我们将定义两个来描述保罗瑞维尔通信系统的数字变量， 让B描述是否英国人正来，并且L描述他们正来的路线。The mathematical variables, B and L, are unusual mathematical variables because each can have only two values. 数学变量，B和L，是不平常的数学变量，因为每一个只能有两个值。We may call those two values by any names we wish :yes /no, true/false, one/zero, high /low, even black/white.我们可以用我们希望的任何名字给两值命名： 是/不，真/假，一/ 0，高/低，甚至黑色/白色。When this type of mathematics was used primarily for analysis of philosophical arguments through symbolic logic, the values of the variables were called true or false, according to the validity of the logical propositions being represented. 当这类数学被通过符号逻辑用于哲学论据分析时，变量的值被叫对还是错，根据逻辑命题被阐述的正确性。 Recently, the names one /zero have come to be preferred(首选的；优先的) by engineers and programmers dealing with digital codes. 近来，命名1/0已经开始被工程师和程序员(处理数字代码)更喜欢These names have the obvious advantage of fitting with the binary (base2) number system for representation of numerical information, but these names occasionally lend confusion to the discussion of digital systems. 这种命名有明显的优势，适用于二进制数字系统(base2)处理数字信息，但是这些命名偶尔对数字系统的讨论造成混乱。 Nevertheless, we shall use 1/0 of one/zero as our two possible states of the digital variables B and L. 虽然如此,我们将使用ONE/ZERO或1/0作为我们数字变量B和L的两种可能的状态Thus the definitions of B and L are B=1 B=0 L=1 L=0 if the British are coming if the British are not coming if coming by sea if coming by land因此B和L的定义是如果英国人将来，B = 1 如果英国人不来，B = 0 如果通过海上来，L = 1 如果由陆路来，L = 0 The first light (B)uniquely determines if he should ride. 第一个光(B) 唯一确定他是否骑马。 When the first light appears, he mounts his horse. 当第一光出现时，他骑上他的马。But he cannot leave until the second light (L) appears (or fails to appear), for the second light reveals the route of the British and hence defines in part the message to be announced. 但是他不能离开直到第2盏灯(L)出现(或者不出现) ,对于第2盏灯来说显示英国人的路线并且因此确定要被宣布的部分消息。Representing Digital Information Electrically. 用电力描述数字信息。In digital electronics, digital variables are represented by logic levels. 在数字电子方面，数字变量通过逻辑级描述。At any given time, a voltage is expected to have one value or another, or more precisely to lie within one region or another. 在任何规定时间，电压预计有一值或者另一个，或者更确切在一个范围内。In a typical system, a voltage between 0 and 0.8 V would be considered a digital zero, a voltage between 0.8-2 V would be forbidden; that is if the voltage fell within this range, you would known that digital equipment needs repair. 在一个典型系统里， 0和0.8 V之间的电压将被认为是数字的零，在0.8和2 V之间的电压将被禁止； 如果电压属于这范围，你知道数字设备需要修理了。 这些定义显示在图4.1中These definitions are shown in Fig.4.1. As an illustration of a digital circuit, we shall consider the amplifier-switch as a NOT circuit. 作为一个数字电路的插图，我们将考虑放大器开关作为一条非门电路。 The output of a NOT circuit is the digital complement, or the opposite, of the input. 非电路的输出是输入数字的“反”或者“补码”。 First we shall represent the definition of the NOT circuit with a truth table. 首先我们将用一个真值表描述非电路的定义。This is shown in Fig.4.2: A represents the input, which may be either 1 or 0 ；B represent the output，which may also be 1 or 0，but depends upon the input. 这在图4.2显示：A描述输入，可能1或者0；B描述输出，也可能是1或者0，但是由输入决定。The NOT, or logical complement, operation is indicated algebraically by the equation under the truth table. 非或者逻辑补的操作，以真值表以下的那些方程式用代数方式被表达。 We shall now define logic levels for the amplifier-switch such that it performs the NOT function. 我们现在将确定放大器开关的逻辑级这样它能执行非的功能。 The input-output characteristic of the circuit is repeated in Fig.403. 电路的输入输出特性被在图4.3中重复。Clearly, we wish 10 V to be in the region for a 1 and 0.7 V to be in the region for a 0. 显然，我们希望10 V为1区域，0.7 V在 0区域。 That is if the input were 10 V (digital 1), the output should be less than 0.7V (digital 0), and vice versa（反之亦然）. 那就是说，输入是10 V(数字1) ,输出应该少于0.7 V(数字0) ,反之亦然。 Hence we might consider making the region for a digital 0 to be from 01 V, and the region for a digital 1 to be, say, from 810 V. 因此，我们可能考虑数字0的范围从0-1V，数字1的范围大约从8 -10 V。This will work but leaves insufficient range for a working digital system. 这对一个工作的数字系统能很好工作，但是离开了能胜任的范围。That is, it is desirable to broaden the range of values in the regions for 1 and 0 to allow for variations in transistors, power supply voltage, noise that might get mixed in with the signal, and the like. 那就是说，希望扩展区域1和0的有效范围，以允许晶体管和电源电压的变化以及混杂在信号里的噪音等因素的影响。In the present case, we can by trail and error （试凑法） determine that the region 01.5 V as a digital 0 works well with 510 V as a digital 1; with these definitions the circuit operates as a NOT circuit, that is, it performs the logical complement。These logic levels are shown in Fig.4.4. 在目前例子中， 我们能以错误操作的范围0-1.5 V作为数字0，好的操作范围5 -10 V作为数字1；即由于这些定义电路作为一条并非电路， 即，它执行合乎逻辑的补足。 这些逻辑级被用图4.4显示。5 Introduction to Electrical Machines电机的介绍5.1 Brief History of Electrical Machines电机的简要历史Electrical machinery has been in existence for many years. 电机存在了多年。The applications of electrical machines have expanded rapidly since their first use many years ago. 从他们多年前的第一个使用，电机的应用已经迅速扩大了。At the present time, applications continue to increase at rapid rate. 目前，应用继续快速增加。 Thomas Edison is given credit for developing the concept of widespread generation and distribution of electrical power. 托马斯爱迪生因为电力的普遍阶段和电力传输（配电）的概念的发展获得荣誉。He performed developmental work on direct-current (DC) generators which were driven by steam engines. 他对被蒸气机驱动的直流(DC)发电机进行了发展的工作。Edisons work with electrical lights and power production led the way to the development of DC motors and associated control equipment. 爱迪生对电灯和电力产品的工作带来了直流电动机和相关控制设备的发展。 Most early discoveries related to electrical machinery operation dealt with direct-current systems. 大多数早期的发明都与处理直流电系统的电机操作有关。Alternating-current (AC) power generation and distribution became widespread a short time later. 交流电(AC)发电机和传输后来才变得广泛。The primary reason for converting to AC power production and distribution was that transformers could be used to increase AC voltage levels for long-distance distribution of electrical power. 转变为交流电能产生与传输的主要原因是变压器能升高交流电压电平以适适合电能的长距离传输。Thus the discovery of transformers allowed the conversion of power production and distribution systems form DC to AC systems. 因此，变压器的发明允许电能的产生与传输系统从DC到AC系统的变换。Presently, almost all electrical power systems produce and distribute three phase alternating current. 目前，几乎所有电力系统产生与传输使用三相交流电。Transformers allow the voltage produced by an AC generator to be increased while decreasing the current level by a corresponding amount. 变压器允许交流发电机产生的电压在以相应数量级减少电流时被增加。This allows long-distance distribution at a reduced current level, reduces power losses, and increases system efficiency. 这样，允许在很低的电流下远距离传输，降低了电力损耗，增加系统效率。 The use of electrical motors has increased for home appliances and industrial and commercial applications for driving machines and sophisticated equipment. 电机的使用增加了家庭用具的使用，驱动电机和复杂设备的工业和商业上的应用也增加了。Many machines and automated industrial equipment now require precise control. 很多机器和自动化的工业设备现在需要准确的控制。Thus motor design and complexity has changed since early DC motors which were used primarily with railroad trains. 由于早期直流电动机主要用于铁路，因此，电动机设计和复杂性都改变了。Motor control methods have now become more critical to the efficient and effective operation of machines and equipment. 对机器和设备的经济性和有效操作来说，电动机控制方法现在已经变得更关键。Such innovations as servo control systems and industrial robots have led to new developments in motor design. 象伺服控制系统和工业机器人这样的革新，已经导致了在电机设计方面的新发展。 Our complex system of transportation has also had an impact on the use of electrical machines. 传输系统的复杂也已经对电机使用有影响。Automobiles and other means of ground transportation use electrical motors for starting and generators for their battery-charging systems. 汽车及其他地面交通工具采用电机启动，并用发电机对蓄电池充电。There has recently been emphasis in the development of electric motor-driven automobiles. 在电机驱动的汽车的发展过程中最近他们被强调了。Aircraft use electrical machines in ways similar to automobiles. 飞机用类似于汽车的方式使用电机。However, they also use sophisticated synchro and servo-controlled machines while in operation. 不过，他们也在运行中使用复杂的同步和伺服控制的机器。7 Electrical Machine Control Systems电子设备控制系统The previous chapters have dealt primarily with the types and characteristics of electrical machines. 先前的章节我们主要处理电子设备的类型和特性。This chapter provides an overview of several power control systems which are used with electrical machines.这个章