电气工程及其自动化专业英语第二章课文翻译
电气工程及其自动化专业英语翻译
零于等须必和数 代的率功间瞬何任在中路电一任�因原个这于由。律定恒守量能循遵须必中路电何任在�上实事 。率功供 提或放释在是件元明表�时示所�b�3�1 图如�0<iu 或 iu��p 果如而。率功收吸在是件元明表�0>iu 或 iu�p�下况情种这在。极正的压电进流流电�说来例惯号符源无于对�例惯号符源无为称被况情种这 。致一的示所�a�3�1 图与须 必向方的流电和性极的压电�正为号符的率功使了为。因原要重的慎谨别特时系关的 u 压电和 i 流电的示 显所�a�3�1 图析分在们我是就这�用作的要主着起性极的压电和向方的流电�时号符率功定确们我在 �负为或正为率功 时何知得何如们我但。的供提件元由是率功么那�的负是号符的率功果如�面方一另。收吸件元被或放释 件元向率功么那�的正是号符的率功个这果如。积乘的流电的它过通和压电端两件元于等率功的供提或收 吸件元一某�率功时瞬为称被是于量变间时个是 p 率功的中�6�1�程方�数函的间时是常通 i 和 u ������� abu- � bau
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中国矿业大学电气工程及自动化专业英语第六版 考试章节第一。二篇课文翻译
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。
电气工程及其自动化英语英译汉
1```In the generator mode ,it,s operating speed isslightly higger than it,s synchronous speed and ie needs magnetizing revctive pover form the symtem that it is connected to in order to suuply pover .在发电方式下他的工作速度比同步转速稍高些，并了解供电力，他需要他所连接的系统吸收磁化无功功率。
2```in the barking mode of operyetion ,a three –phase indection motor running at a steady –speedcan be brought to a quick stop by interchanging two of stator leads感应电机运行电动状态时，其转速低于同步转速，运行在发电状态时，其转速高于同步转速，这就需要从与之间相连的系统电源提供励磁的无功功率。
3```obviously ,dc machine applications are very significant,but the advantages of the dc machinemmust be weighed against its greatr initial investment cost and the maintenance problems associated with its brush-commutator system..同步是指状态运行时点击以恒定的转速和频率运行。
4```with a cylindyical rotor the reluctance of the magnetic circuit of the field is independent of itsactual diretion and relative to the direct axis.圆柱形转子的磁场磁路的磁阻与直轴有关，而与磁场的实际方向无关。
电气工程及其自动化专业英语翻译
图2-2显示了这样一个系统的组成部分。中间的 圆圈代表了两种类型的信号处理（数字和模拟）， 而处于信号处理框之间的方框表示模拟信号向等效 数字形式（A/D即模拟到数字）的转换，以及从数 字信号向相应的模拟形式（D/A即数字到模拟）的 逆转换。剩下的方框涉及输入和输出——取得信号 以及从处理系统输出信号。 从物理系统获得的很多电气信号是从被称为传感 器的器件中输入的。我们已经碰到了一个模拟传感 器的例子。即热电偶。它把温度的变化（物理变量） 转换成电压（电气变量）。通常，传感器是一种将 物理或机械变量转换成等效电压或电流信号的器件。 然而，不同于热电偶例子，大多数传感器需要一些 形式的电激励以驱动传感器。
可能的值0和1来证明每个表达式的正确 性。例如采用A=0,B=0,C=0，或A=1, B=0,C=0等等，在每个表达式中，结合律表 明如何把变量进行重组。 对于“与”有（AB）C＝A（BC）＝ （AC）B而对于“或”有（A＋B）＋C＝A ＋（B＋C）＝（A＋C）＋B 这个法则表明我们可以采用变量的不 同组合而不改变代数表达式的正确性。交换 率表明了变量的顺序。 对于“与”有AB＝BA，而对于“或” 有A＋B＝B＋A。
一个系统的输出可以有多种形式，这取决于包 含在输入信号中的信息所起的作用。我们可以选择 何种方式显示这些信息，无论是以模拟形式（例如， 使用一种仪表，仪表的指针的位置指明我们所感兴 趣的变量的大小）或是以数字形式（使用一套数字 显示元件，显示对应于我们所感兴趣的变量的数 字）。其它的可能的情况下是将输出转换成声能 （利用扬声器），或是将输出作为另一个系统的输 入，或是利用输出作为控制信号来产生某个动作。
数字设备的布尔代数法则 布尔代数与任何代数一样具有结合律、 交换律和分配律。为了表示代数的特性我们 使用变量A,B和C以及诸如此类的变量。为了 写出这些可能取值为0或1的各个变量之间的 相互关系，我们采用来Ā表示“非A”，因此 如果A＝1，那么Ā＝0。每个变量的补码用每 个变量上方加一横线来表示，B的补码就是Ā 也即“非B”。同时还存在两个固定的量。第 一个量是单位量，即I＝1，另外一个量是零， 即null＝0。
电气工程及其自动化专业英语翻译
第一章电路基本原理第一节电流和电压u(t)和i(t)这两个变量是电路中最基本的两个变量，它们刻划了电路的各种关系。
电荷和电流电荷的概念是用来解释所有电气现象的基本概念。
也即，电路中最基本的量是电荷。
电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。
我们从基础物理得知一切物质是由被称为原子的基本构造部分组成的，并且每个原子是由电子，质子和中子组成的。
我们还知道电子的电量是负的并且在数值上等于1.602100×10-12C，而质子所带的正电量在数值上与电子相等。
质子和电子数量相同使得原子呈现电中性。
让我们来考虑一下电荷的流动。
电荷或电的特性是其运动的特性，也就是，它可以从一个地方被移送到另一个地方，在此它可以被转换成另外一种形式的能量。
当我们把一根导线连接到某一电池上时(一种电动势源)，电荷被外力驱使移动；正电荷朝一个方向移动而负电荷朝相反的方向移动。
这种电荷的移动产生了电流。
我们可以很方便地把电流看作是正电荷的移动，也即，与负电荷的流动方向相反，如图1－1所示。
这一惯例是由美国科学家和发明家本杰明－富兰克林引入的。
虽然我们现在知道金属导体中的电流是由负电荷引起的，但我们将遵循通用的惯例，即把电流看作是正电荷的单纯的流动。
于是电流就是电荷的时率，它是以安培为单位来度量的。
从数学上来说，电流i、电荷q以及时间t之间的关系是：从时间t0到时间t所移送的电荷可由方程（1－1）两边积分求得。
我们算得：我们通过方程（1－1）定义电流的方式表明电流不必是一个恒值函数，电荷可以不同的方式随时间而变化，这些不同的方式可用各种数学函数表达出来。
电压，能量和功率在导体中朝一个特定的方向移动电荷需要一些功或者能量的传递，这个功是由外部的电动势来完成的。
图1－1所示的电池就是一个典型的例子。
这种电动势也被称为电压或电位差。
电路中a、b两点间的电压等于从a到b移动单位电荷所需的能量（或所需做的功）。
数学表达式为：式中w是单位为焦耳的能量而q是单位为库仑的电荷。
电气工程专业英语汉语及翻译
电气工程专业英语姓名：吕海龙学号：20080345班级：08电气专业：电气工程及其自动化Electric Devices and SystemsAlthough transformers have no moving parts , they are essential to electromechanical energy conversion . They make it possible to increase or decrease the voltage lever that results in low costs ,and can be distributed and used safely . In addition , they can provide matching of impedances , and regulate the flow of power in a network.When we see a transformer on a utility pole all we is a cylinder with a few w ires sticking out. These wires enter the transformer through bushings that provide isolation between the wires and the tank. Inside the tank these is an iron core linking coils, most probably made with copper, and insulated. The system of insulation is also associated with that of cooling the core/coil assembly. Often the insulation is paper, and the whole assembly may be immersed in insulating oil, used to both increase the dielectric strength of the paper and to transfer beat from the core-coil assembly to the outer walls of the tank to air. Figure shows the cutout of a typical distribution transformer.Few ideal versions of human constructions exist, and the transformer offers no exception. An ideal transformer is based on very simple concepts, and a large number of assumptions. This is the transformer one learns about in high school.Let us take an iron core with infinite permeability and two coils wound around it, one with N1 and the other with N2 turns, as shown in figure. All the magnetic flux is to remain in the iron. We assign sots at one terminal of each coil in the following fashion: if the flux in the core changes, inducing a voltage in the coils, and the dotted terminal of one coil is positive with respect its other terminal, so is the dotted terminal of the other coil. Or, the corollary to this, current into dotted terminals produces flux in the same direction,Assume that somehow a time varying flux is established in the iron. Then the flux linkages in each coil will be. V oltages will be induced in these two coil.On the other hand, currents flowing in the coils are related to the field intensity H. if currents flowing in the direction shown, i1 into the dotted terminal of coil 1, and i2 out of the dotted terminal of coil 2. we recognize that this is practically impossible, but so is the existence of an ideal transformer.Equations describe this ideal transformer, a two port network. The symbol of a network that is defined by these two equations is in the figure. An ideal transformer has an interesting characteristic. A two-port network that contains it and impedances can be replaced by an equivalent other, as discussed below. Consider the circuit in figure. Seen as a two port network. Generally a circuit on a side 1 can be transferred to side 2 by multiplying its component impedances , the voltage sources and the current sources, while keeping the topology the same.To develop the equivalent for a transformer we’ll gradually relax the assumptions that we had first imposed. First we’ll relax the assumption that the permeability of the iron is infinite. In that case equation does not revert to, but rather it becomes where is the reluctance of the path around the core of the transformer and the flux on this path. To preserve the ideal transformer equations as part of our new transformer, we can split i1 to two components: one i1, will satisfy the ideal transformer equation, and the other, i1 will just balance the right hand side. The figure shows this.We can replace the current source, i1 , with something simpler if we remember that the rate of change of flux is related to the induced voltage.Since the current i1 flows through something , where the voltage across it Is proportional to its derivative, we can consider that this something could be an inductance. This idea gives rise tothe equivalent circuit in figure,. Let us now relax the assumption that all the flux has to remain in the iron as shown in figure. Let us call the flux in the iron, magnetizing flux, the flux that leaks out of the core and links only coil 1. since links only coil 1, then it should be related only to the current there, and the same should be true for the second leakage flux.Again for a given frequency, the power losses in the core increase with the voltage. These losses cannot be allowed to exceed limit, beyond which the temperature of the hottest spot in the transformer will rise above the point that will decrease dramatically the life of the insulation. Limits therefore are put to E1 and E2, and these limits are the voltage limits of the transformer.Similarly, winding Joule losses have to be limited, resulting in limits to the currents I1 and I2.Typically a transformer is described by its rated voltages, that give both the limits and turns radio. The ratio of the rated currents is the inverse of the ratio of the voltages if we neglect the magnetizing current. Instead of the transformer rated currents, a transformer is described by its rated apparent power.Under rated conditions, maximum current and voltage, in typical transformers the magnetizing current, does not exceed 1% of the current in the transformer. Its effect therefore in the voltage drop on the leakage inductance and winding resistance is negligible.Under maximum current, total voltage drops on the winding resistances and leakage inductances do not exceed in typical transformer 6% of the rated voltage. The effect therefore of the winding current on the voltages E1 and E2 is small, and their effect on the magnetizing current can be neglected.These considerations allow us to modify the equivalent circuit in figure, to obtain the slightly inaccurate but much more useful equivalent circuits in figures.Adjustable Speed DrivesBy definition, adjustable speed drives of any type provide a means of variably changing speed to better match operating requirements. Such drives are available in mechanical, fluid and electrical typed.The most common mechanical versions use combinations of belts and sheaves, or chains and sprockets, to adjust speed in set, selectable ratios-2:1,4:1,8:1 and so forth. Traction drives, a more sophisticated mechanical control scheme, allow incremental speed adjustments. Here, output speed is varied by changing the contact points between metallic disks, or between balls and cones.Adjustable speed fluid drives provide smooth, stepless adjustable speed control. There are three major types. Hydrostatic drives use electric motors or internal combustion engines as prime movers in combination with hydraulic pumps, which in turn drive hydraulic motors. Hydrokinetic and hydroviscous drives directly couple input and output shafts. Hydrokinetic versions adjust speed by varying the amount of fluid in a vortex that serves as the input-to-output coupler. Hydroviscous drives, also called oil shear drives, adjust speed by controlling oil-film thickness, and therefore slippage, between rotating metallic disk.An eddy current drive, while technically an electrical drive, nevertheless functions much like a hydrokinetic or hydrovidcous fluid drive in that it serves as a coupler between a prime mover and driven load. In an eddy current drive, the coupling consists of a primary magnetic field and secondary fields created by induced eddy currents. They amount of magnetic slippage allowed among the fields controls the driving speed.In most industrial applications, mechanical, fluid or eddy current drives are paired with constant-speed electric motors. On the other hand, solid state electrical drives, create adjustable speed motors, allowing speeds from zero RPM to beyond the motor’s base speed. Controlling the speed of the motor has several benefits, including increased energy efficiency by eliminating energy losses in mechanical speed changing devices. In addition, by reducing, or often eliminating, the need for wear-prone mechanical components, electrical drives foster increased overall system reliability, as well as lower maintenance costs. For these and other reasons, electrical drives are the fastest growing type of adjustable speed drive..There are two basic drive types related to the type of motor controlled-dc and AC. A DC direct current drive controls the speed of a DC motor by varying the armature voltage (and sometimes also the field voltage ). An alternating current drive controls the speed of an AC motor by varying the frequency and voltage supplied to the motor.Direct current drives are easy to apply and technologically straightforward, They work by rectifying AC voltage from the power line to DC voltage, then feeding adjustable voltage to a DC motor. With permanent magnet DC motors, only the armature voltage is controlled. The more voltage supplied, the faster the armature turns. With wound-field motors, voltage must be supplied to both the armature and the field. In industry, the following three types of DC drives are most common, as shown in the figure.Drives: these are named for the silicon controlled rectifiers (also called thyristors ) used to convert AC to controlled voltage DC. Inexpensive and easy to use, these drives come in a variety of enclosures, and in unidirectional or reversing styles.Regenerative SCR Drives: Also called four quadrant drives, these allow the DC motor to provide both motoring and braking torque, Power coming back from the motor during braking is regenerated back to the power line and not lost.Pulse Width Modulated DC Drives: Abbreviated PWM and also called, generically, transistorized DC drives, these provide smoother speed control with higher efficiency and less motor heating, Unlike SCR drives, PWM types have three elements. The first converts AC to DC, the second filters and regulates the fixed DC voltage, and the third controls average voltage by creating a stream of variable width DC pulses. The filtering section and higher level of control modulation account for the PWM drive’s improved performance compared with a common SCR drive.AC drive operation begins in much the same fashion as a DC drive. Alternating line voltage is first rectified to produce DC. But because an AC motor is used, this DC voltage must be changed back, of inverted, to an adjustable-frequency alternating voltage. The drive’s inverter section accomplishes this, In years past, this was accomplished using SCR. However, modern AC drives use a series of transistors to invert DC to adjustable-Frequency AC. An example is shown in figure.This synthesized alternating current is then fed to the AC motor at the frequency and voltage required to produce the desired motor speed. For example, a 60 Hz synthesized frequency, the same as standard line frequency in the United states, produces 100% of rated motor speed. A lower frequency produces a lower speed, and a higher frequency a higher speed. In this way, an AC drive can produce motor speeds from, approximately,15 to200% of a motor’s normally rated RPM-- by delivering frequencies of 9 HZ to 120 Hz, respectively.Today, AC drives are becoming the systems of choice in many industries,. Their use ofsimple and rugged three-phase induction motor means that AC drive systems are the most reliab le and least maintenance prone of all. Plus, microprocessor advancements have enabled the creation of so-called vector drives, which provide greatly enhance response, operation down to zero speed and positioning accuracy. V ector drives, especially when combined with feedback devices such as tachometers, encoders and resolvers in a closed-loop system, are continuing to replace DC drives in demanding applications. An Example is shown in the figure.By far the most popular AC drive today is the pulse width modulated type. Though originally developed for smaller-horsepower applications, PWM is now used in drives of hundreds or even thousands of horsepower—as well as remaining the staple technology in the vast majority of small integral and fractional horsepower ―micro‖ and ―sub-micro‖ AC drives, as shown in the figure.Pulse width modulated refers to the inverter’s ability to vary the output voltage to the motor by altering the width and polarity of voltage pulses, The voltage and frequency are synthesized using this stream of voltage pulses. This is accomplished through microprocessor commands to a series of power semiconductors that serve as on-off switches. Today, these switches are usually IGBTs, of isolated gate bipolar transistor. A big advantage to these devices is their fast switching speed resulting in higher pulse of carrier frequency, which minimizes motor noise.Power semiconductor devicesThe modern age of power electronics began with the introduction of thyristors in the late 1950s. Now there are several types of power devices available for high-power and high-frequency applications. The most notable power devices are gate turn-off thyristor, power darlington transistors, power mosfets, and insulated-gate bipolar transistors. Power semiconductor devices are the most important functional elements in all power conversion applications. The power devices are mainly used as switches to convert power from one form to another. They are used in motor control systems, uninterrupted power supplies, high-voltage dc transmission, power supplies, induction heating, and in many other power conversion applications. A review of the basic characteristics of these power devices is presented in this section.The thyristor, also called a silicon-controlled rectifier, is basically a four-layer three-junction pn device. It has three terminals: anode, cathode, and gate. The device is turned on by applying a short pulse across the gate and cathode. Once the device turns on, the gate loses its control to turn off the device. The turn-off is achieved by applying a reverse voltage across the anode and cathode. The thyristors symbol and its volt-ampere characteristics are shown in the figure. There are basically two classifications of thyristors: converter grade and inverter grade. The difference between a converter-grade and an inverter-grade thyristor is the low turn –off time (on the order of a few microseconds) for the latter. The converter-grade thyristors are slow type and are used in natural commutation (or phase-controlled) applications. Inverter-grade thyristors are used in forced commutation applications such as dc-dc choppers and dc-ac inverters. The inverter-grade thyristors are turned off by forcing the current to zero using an external commutation circuit. This requires additional commutating components, thus resulting in additional losses in the inverter.Thyristors are highly rugged devices in terms of transient currents, di / dt, and dv/dt capability. The forward voltage drop in thyristors is about 1.5 to 2 V, and even at higher currents of the order of 100 A, it seldom exceeds 3 V. While the forward voltage determines the on-state power loss of the device at any given current, the switching power loss becomes a dominating factor affecting the device junction temperature at high operating frequencies. Because of this, themaximum switching frequencies possible using thyristors are limited in comparison with other power devices considered in this section.Thyristors have withstand capability and can be protected by fuses. The nonrepetitive surge current capability for thyristors is about 10 times their rated root mean square current. They must be protected by snubber networks for dv/dt and di/dt effects. If the specified dv/dt is exceeded, thyristors may start conducting without applying a gate pulse. In dc-to-ac conversion applications it is necessary to use an antiparalled diode of similar rating across each main thyristor. Thyristors are available up to 6000 V, 3500 A.Power mosfets are marketed by different manufacturers with differences in internal geometry and with different names such as megamos, hexfet, sipmos, and tmos. They have unique features that make them potentially attractive for switching applications. They are essentially voltage-driven rather than current-driven devices, unlike bipolar transistors.The gate of a mosfet is isolated electrically from the source by a layer of silicon oxide. The gate draws only a minute leakage current of the order of nanoamperes. Hence the gate drive circuit is simple and power loss in the gate control circuit is practically negligible. Although in steady state the gate draws virtually no current, this is not so under transient conditions. The gate-to-source and gate-to-drain capacitances have to be charged and discharged appropriately to obtain the desired switching speed, and the drive circuit must have a sufficiently to output impedance to supply the required charging and discharging currents. The circuit symbol of a power mosfet is shown in the figure.Power mosfets are majority carrier devices, and there is no minority carrier storage time. Hence they have exceptionally fast rise and fall times. They are essentially resistive devices when turned on, while bipolar transistors present a more or less constant over the normal operating range. Power dissipation in mosfets is I, and in bipolar it is Ic, and in bipolar it is Id. At low currents, therefore, a power mosfet may have a lower conduction loss than a comparable bipolar device, but at higher currents, the conduction loss will exceed that of bipolar. Also, the R increases with temperature.An important feature of a power mosfet is the absence of a secondary breakdown effect, which is present in a bipolar transistor, and as a result, it has an extremely rugged switching performance. In mosfets, R increases with temperature, and thus the current is automatically diverted away from the hot spot. The drain body junction appears as an antiparalled diode between source and drain. Thus power mosfet will not support voltage in the reverse direction. Although this in verse diode is relatively fast, it is slow by comparison with the mosfet. Recent devices have the didde recovery time as low as 100 ns. Since mosfet cannot be protected by fuses, an electronic protection technique has to be used.With the advancement in MOS technology, ruggedized MOSF are replacing the conventional MOSEFs. The need to ruggedize power MOSFETs is related to device reliability. If a MOSFET is operating within its specification range at all times, its chances for failing catastrophically are minimal. However, if its absolute maximum rating is exceeded, failure probability increases dramatically. Under actual operating conditions, a MOSFET may be subjected to transients—either externally from the power bus supplying the circuit or from the circuit itself due, for example, to inductive kicks going beyond the absolute maximum ratings. Such conditions are likely in almost every application, and in most cases are beyond a designer’s control. Rugged devices are made to be more tolerant for over-voltage transients. Ruggedness is the ability of aMOSFET to operate in an environment of dynamic electrical stresses, without activating any of the parasitic bipolar junction transistors. The rugged device can withstand higher levels of diode recovery dv/dt and static dv/dt.（单词量：3115）译文：变压器尽管变压器没有旋转的不见，但是它在本质上还是属于几点能量交换设备。
电气工程及其自动化专业英语课文翻译
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课后翻译
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。
(完整版)电气工程及其自动化专业英语第二章课文翻译
第二章第一篇To say that we live in an age of electronics is an understatement. From the omnipresent integrated circuit to the equally omnipresent digital computer, we encounter electronic devices and systems on a daily basis. In every aspect of our increasingly technological society— whether it is science, engineering, medicine, music, maintenance, or even espionage—the role of electronics is large, and it is growing.谈论关于我们生活在一个电子学时代的论调是一种空泛的论调。
从无处不在的集成电路到同样无处不在的数字计算机，我们在日常活动中总会遇到电子设备和电子系统。
在我们日益发展的科技社会的方方面面——无论是在科学、工程、医药、音乐、维修方面甚至是在谍报方面——电子学的作用是巨大的，而且还将不断增强。
In general, all of the tasks with which we shall be concerned can be classified as "signal-processing“tasks. Let us explore the meaning of this term一般说来，我们将要涉及到的工作被归结为“信号——处理”工作，让我们来探究这个术语的含义吧。
A signal is any physical variable whose magnitude or variation with time contains information. This information might involve speech and music, as in radio broadcasting, a physical quantity such as the temperature of the air in a room, or numerical data, such as the record of stock market transactions. The physical variables that can carry information in an electrical system are voltage and current. When we speak of "signals", therefore, we refer implicitly to voltages or currents. However, most of the concepts we discuss can be applied directly to systems with different information-carrying variables. Thus, the behavior of a mechanical system (in which force and velocity are the variables) or a hydraulic system (in which pressure and flow rate are the variables) can often be modeled or represented by an equivalent electrical system. An understanding of the behavior of electrical systems, therefore, provides a basis for understanding a much broader range of phenomena. 信号就是其与时间有关的量值或变化包含信息的任何物理变量。
电气工程及其自动化专业英语翻译
Semiconductor switches are very important and crucial components inpower electronic systems.these switches are meant to be the substitutionsof 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，中半导体开关是特别重要和重点零件。
半导体开关将要替代机械开关,但半导体资料的性质和生产过程严重限制了他们。
Switching losses开关消耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses.电力电子变换器的功率消耗分为开关消耗和寄生消耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses ofcapacitors,the eddy and the hysteresis losses.寄生损失的绕组电感器、变压器的阻力、介电消耗的电容器, 涡流和磁滞消耗the switching losses are significant and can be managed.这个开关消耗是特别重要的, 能够被办理。
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.他们能够分为三个部分:通态消耗，断态消耗和转换过程中产生的消耗。
电气工程及其自动化专业英语翻译
Electrical Energy TransmissionFrom reference 1Growing populations and industrializing countries create huge needs for electrical energy. Unfortunately, electricity is not always used in the same place that it is produced, meaning long-distance transmission lines and distribution systems are necessary. But transmitting electricity over distance and via networks involves energy loss.So, with growing demand comes the need to minimize this loss to achieve two main goals: reduce resource consumption while delivering more power to users. Reducing consumption can be done in at least two ways: deliver electrical energy more efficiently and change consumer habits.Transmission and distribution of electrical energy require cables and power transformers, which create three types of energy loss:the Joule effect, where energy is lost as heat in the conductor (a copper wire, for example);magnetic losses, where energy dissipates into a magnetic field;the dielectric effect, where energy is absorbed in the insulating material.The Joule effect in transmission cables accounts for losses of about 2.5 % while the losses in transformers range between 1 % and 2 % (depending on the type and ratings of the transformer). So, saving just 1 % on the electrical energy produced by a power plant of 1 000 megawatts means transmitting 10 MW more to consumers, which is far from negligible: with the same energy we can supply 1 000 - 2 000 more homes.Changing consumer habits involves awareness-raising programmers, often undertaken by governments or activist groups. Simple things, such as turning off lights in unoccupied rooms, or switching off the television at night (not just putting it into standby mode), or setting tasks such as laundry for non-peak hours are but a few examples among the myriad of possibilities.On the energy production side, building more efficient transmission anddistribution systems is another way to go about it. High efficiency transformers, superconducting transformers and high temperature superconductors are new technologies which promise much in terms of electrical energy efficiency and at the same time, new techniques are being studied. These include direct current and ultra high voltage transmission in both alternating current and direct current modes.Keywords: electrical energy transmissionFrom reference 2Disturbing loads like arc furnaces and thyristor rectifiers draw fluctuating and harmonic currents from the utility grid. These non sinusoidal currents cause a voltage drop across the finite internal grid impedance, and the voltage waveform in the vicinity becomes distorted. Hence, the normal operation of sensitive consumers is jeopardized.Active filters are a means to improve the power quality in distribution networks. In order to reduce the injection of non sinusoidal load currents shunt active filters are connnected in parallel to disturbing loads (Fig. 1). The active filter investigated in this project consists of a PWM controlled three-level VSI with a DC link capacitor.The VSI is connected to the point of common coupling via a transformer. The configuration is identical with an advanced static var compensator.The purpose of the active filter is to compensate transient and harmonic components of the load current so that only fundamental frequency components remain in the grid current. Additionally, the active filter may provide the reactive power consumed by the load. The control principle for the active filter is rather straightforward: The load current ismeasured, the fundamental active component is removed from the measurement, and the result is used as the reference for the VSI output current.In the low voltage grid, active filters may use inverters based on IGBTs with switching frequencies of 10 kHz or more. The harmonics produced by those inverters are easily suppressed with small passive filters. The VSI can be regarded nearly as an ideally controllable voltage source. Inmedium voltage applications with power ratings of several MVA, however, the switching frequency of today’s VSIs is limited to somehundred Hertz. Modern high power IGCTs can operate at around 1 kHz. Therefore, large passive filters are needed in order to remove the current ripple generated by the VSI. Furthermore, in fast control schemes the VSI no longer represents an ideal voltage source because the PWM modulator produces a considerable dead-time.In this project a fast dead-beat algorithm for PWM operated VSIs is developed [1].This algorithm improves the load current tracking performance and the stability of the active filter. Normally, for a harmonics free current measurement the VSI current would be sampled synchronously with the tips of the triangular carriers. Here, the current acquisition is shifted in order to minimize the delays in the control loop. The harmonics now included in themeasurement can be calculated and subtracted from the VSI current. Thus, an instantaneous current estimation free of harmonics is obtained.Keywords: active filtersFrom reference 3This report provides background information on electric power transmission and related policy issues. Proposals for changing federal transmission policy before the 111th Congress include S. 539, the Clean Renewable Energy and Economic Development Act, introduced on March 5, 2009; and the March 9, 2009, majority staff transmission siting draft of the Senate Energy and Natural Resources Committee. The policy issues identified and discussed in this report include:Federal Transmission Planning: several current proposals call for the federal government to sponsor and supervise large scale, on-going transmission planning programs. Issues for Congress to consider are the objectives of the planning process (e.g., a focus on supporting the development of renewable power or on a broader set of transmission goals), determining how much authority new interconnection-wide planning entities should be granted, the degree to which transmission planning needs to consider non-transmission solutions to power market needs, what resources the executive agencies will need to oversee the planning process, and whether the benefits for projects included in the transmission plans (e.g., a federal permitting option) will motivate developers to add unnecessary features and costs to qualify proposals for the plan.Permitting of Transmission Lines: a contentious issue is whether the federal government should assume from the states the primary role in permitting new transmission lines. Related issues include whether Congress should view management and expansion of the grid as primarily a state or national issue, whether national authority over grid reliability (which Congress established in the Energy Policy Act of 2005) can be effectively exercised without federal authority over permitting, if it is important to accelerate the construction of new transmission lines (which is one of the assumed benefits of federal permitting), and whether the executive agencies are equipped to take on the task of permitting transmission lines.Transmission Line Funding and Cost Allocation: the primary issues are whether the the federal government should help pay for new transmission lines, and if Congress should establish a national standard for allocating the costs of interstate transmission lines to ratepayers.Transmission Modernization and the Smart Grid: issues include the need for Congressional oversight of existing federal smart grid research, development, demonstration, and grant programs; and oversight over whether the smart grid is actually proving to be a good investment for taxpayers and ratepayers.Transmission System Reliability: it is not clear whether Congress and the executive branch have the information needed to evaluate the reliability of the transmission system. Congress may also want to review whether the power industry is striking the right balance between modernization and new construction as a means of enhancing transmission reliability, and whether the reliability standards being developed for the transmission system are appropriate for a rapidly changing power system.2 中文翻译及分析出资文献 1：人口增长和工业化国家导致电力能源的庞大需求量. 不幸的是, 电力的使用和生产常常不是在相同的地方，意味着长距离传输线路配电系统是必需的. 然而长距离输电以及通过网络这就涉及到能量损耗的问题。
电气专业英语课文翻译
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。
电气工程及其自动化专业英语翻译
第一章 电路基本原理第一节 电流和电压u(t)和i(t)这两个变量是电路中最基本的两个变量，它们刻划了电路的各种关系。
电荷和电流电荷的概念是用来解释所有电气现象的基本概念。
也即，电路中最基本的量是电荷。
电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。
我们从基础物理得知一切物质是由被称为原子的基本构造部分组成的，并且每个原子是由电子，质子和中子组成的。
我们还知道电子的电量是负的并且在数值上等于 1.602100×10-12C ，而质子所带的正电量在数值上与电子相等。
质子和电子数量相同使得原子呈现电中性。
让我们来考虑一下电荷的流动。
电荷或电的特性是其运动的特性，也就是，它可以从一个地方被移送到另一个地方，在此它可以被转换成另外一种形式的能量。
当我们把一根导线连接到某一电池上时(一种电动势源)，电荷被外力驱使移动；正电荷朝一个方向移动而负电荷朝相反的方向移动。
这种电荷的移动产生了电流。
我们可以很方便地把电流看作是正电荷的移动，也即，与负电荷的流动方向相反，如图1－1所示。
这一惯例是由美国科学家和发明家本杰明－富兰克林引入的。
虽然我们现在知道金属导体中的电流是由负电荷引起的，但我们将遵循通用的惯例，即把电流看作是正电荷的单纯的流动。
于是电流就是电荷的时率，它是以安培为单位来度量的。
从数学上来说，电流i 、电荷q 以及时间t 之间的关系是：从时间t0到时间t 所移送的电荷可由方程（1－1）两边积分求得。
我们算得：我们通过方程（1－1）定义电流的方式表明电流不必是一个恒值函数，电荷可以不同的方式随时间而变化，这些不同的方式可用各种数学函数表达出来。
电压，能量和功率在导体中朝一个特定的方向移动电荷需要一些功或者能量的传递，这个功是由外部的电动势来完成的。
图1－1所示的电池就是一个典型的例子。
这种电动势也被称为电压或电位差。
电路中a 、b 两点间的电压等于从a 到b 移动单位电荷所需的能量（或所需做的功）。
电气工程及其自动化专业英语第二章第四节
Energy conversion
01
Motors and power electronics are essential components of power systems, converting electrical energy into mechanical energy and vice verse
Coordinated operation
Multiple power plants and transmission lines are connected to form a large, interconnected grid that allows electricity to be transmitted over long distances
Definition of Electrical Enginetomation technology refers to the use of machines, systems, and processes that can perform tasks without human intervention It involves the integration of sensors, actors, controllers, and information technology to achieve effectiveness, accuracy, and repeatable operations
Transmission
High voltage transmission lines that carry electricity over long distances to ensure the reliable supply of power to the grid
电气工程专业英语+unt2
ignitron n. 引燃管；放电管
cycloconverter n. 周波变换器；双向离子变频器
triac n. <美>[电]三端双向可控硅开关元件
a scope of 一个范围 spectrum n. 谱，光谱；能谱；
2.1 Introduction text
Power electronics is the application of solid-state electronics for the control and conversion of electric power.
In 1976 power MOSFET becomes commercially available. Then in 1982 the insulated gate bipolar transistor (IGBT) was introduced.
Note：①commercially available市场上能买到的
William Shockley at the Bell Telephone Laboratory.
Note：①： started with 开始于； ②mercury arc rectifier 汞弧整流器.
2.1 Introduction text
In 1960s the switching speed of bipolar junction tran-
It also refers to ① a subject of research in electrical engineering which deals with design, control, computation and integration of nonlinear, time varying energy processing electronic systems with fast dynamics②.
电气工程及其自动化专业英语翻译
Semiconductor switches are very important and crucial components in powerelectronic 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。
电气工程及其自动化专业英语
voltage drop 电压降 volt-ampere characteristics 伏安特性
metal-filament lamp 金属丝灯泡
carbon-filament lamp 碳丝灯泡
non-linear characteristics 非线性特性
Unit 1 Circuit Elements and Parameters
• With time-invariant currents and voltages, the magnetic anห้องสมุดไป่ตู้ electric fields of the associated electric plant are also timeinvariant. This is the reason why no e.m.f.s of self- (or mutual-)induction（自感或互感）appear in D.C. circuits, nor are there （倒装结构）any displacement currents （位移电 流）in the dielectric surrounding the conductors(导体周围的 电介质）.
Techniques
Unit 1 Specialized English Words
circuit components 电路元件
circuit parameters 电路参数
the dielectric 电介质
storage battery 蓄电池
electric circuit 电路
wire导线
电气工程及其自动化专业英语
Specialized English for Electrical Engineering ＆ Its Automation
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电气工程及其自动化专业英语第二章课文翻译第二章第一篇To say that we live in an age of electronics is an understatement. From the omnipresent integrated circuit to the equally omnipresent digital computer, we encounter electronic devices and systems on a daily basis. In every aspect of our increasingly technological society—whether it is science, engineering, medicine, music, maintenance, or even espionage—the role of electronics is large, and it is growing.谈论关于我们生活在一个电子学时代的论调是一种空泛的论调。
从无处不在的集成电路到同样无处不在的数字计算机，我们在日常活动中总会遇到电子设备和电子系统。
在我们日益发展的科技社会的方方面面——无论是在科学、工程、医药、音乐、维修方面甚至是在谍报方面——电子学的作用是巨大的，而且还将不断增强。
In general, all of the tasks with which we shall be concerned can be classified as "signal-processing“tasks. Let us explore the meaning of this term一般说来，我们将要涉及到的工作被归结为“信号——处理”工作，让我们来探究这个术语的含义吧。
A signal is any physical variable whose magnitude or variation with time contains information. This information might involve speech and music, as in radio broadcasting, a physical quantity such as the temperature of the air in a room, or numerical data, such as the record of stock market transactions. The physical variables that can carry information in an electrical system are voltage and current. When we speak of "signals", therefore, we refer implicitly to voltages or currents. However, most of the concepts we discuss can be applied directly to systems with different information-carrying variables. Thus, the behavior of a mechanical system (in which force and velocity are the variables) or a hydraulic system (in which pressure and flow rate are the variables) can often be modeled or represented by an equivalent electrical system. Anunderstanding of the behavior of electrical systems, therefore, provides a basis for understanding a much broader range of phenomena. 信号就是其与时间有关的量值或变化包含信息的任何物理变量。
这种信息或许像无线电广播的演讲和音乐，或许是像室内温度的物理量，或许像股市交易记录的数字数据。
在电气系统中能够载有信息的物理变量是电压和电流。
因此当我们谈到“信号”，我们不言而喻指的是电压和电流，然而，我们要讨论的大多数概念是可以被直接应用于载有不同信息的变量的系统，因此，一个机械系统（在这个系统中力和速度是其变量）或者液压系统（在这个系统中压力和流速是其变量）的性能通常可以用一个等效的电气系统来模拟或表示。
因此，我们对于电气系统性能的理解为理解更宽领域的现象打下了一个基础。
A signal can carry information in two different forms. In an analog signal the continuous variation of the voltage or current with time carries the information. An example, in Fig.2-l, is the voltage produced by a thermocouple pair when the two junctions are at differenttemperatures. As the temperature difference between the two junctions varies, the magnitude of the voltage across the thermocouple pair also varies. The voltage thus provides an analog representation of the temperature difference.一个信号可以以两种形式来承载信息。
在一个模拟信号中电压或电流随时间而产生的连续变化载有信息。
在图2-1中，当一对热电偶的接头处于不同的温度时由热电偶所产生的电压就是一个例子。
当两个接头之间的温度差改变时，一对热电偶两端的电压也将改变。
于是电压就提供了温度差的模拟表现形式The other kind of signal is a digital signal. A digital signal is one that can take on values within two discrete ranges. Such signals are used to represent ON-OFF or YES-NO information. An ordinary household thermostat delivers a digital signal tocontrol the furnace. When the room temperature drops below a preset value, the thermostat switch closes turning on the furnace. Once the room temperature rises high enough, the switch opens turning off thefurnace. The current through the switch provides a digital representation of the temperature variation: ON equals "too cold" while OFF equals "not too cold".另一种的信号是数字信号。
数字信号是在两个离散的范围内能够呈现一定数值的信号。
这种信号常用以表示“开—关”或“是—不是”信息。
一个普通的家用恒温器传递一种数字信号来控制炉子当房间的温度下降到预定温度以下时，恒温器的开关合上使炉子开始加热；一旦房间的温度上升到足够高，开关就断开使炉子关闭。
流过开关的电流提供了温度变化的数字表示：ON即为“太冷”而OFF即为“不太冷”A signal-processing system is an interconnection of components and devices that can accept an input signal or a group of input signals, operate on the signals in some fashion either to extract or improve the quality of the information, and present the information as an output in the proper form at the proper time.一个信号处理系统是某些元件或设备之间的相互连接，这些元件和设备能够接收一个输入信号或一组输入信号，信号处理系统以某种方式来处理这些信号即提取这些信号或提高这些信号的品质，然后在适当的时间以适当的形式把这个信号表示为输出量。
Fig.2-2 illustrates the components in such a system. The central circles represent the two types of signal processing (digital and analog), while theblock between the two signal- processing blocks represents the conversion of an analog signal to equivalent digital form (A/D=Analog-to-Digital) and the reverse conversion of a digital signal to the corresponding analog form (D/A=Digital-to-Analog). The remaining blocks involve inputs and outputs— getting signals into and out of the processing system.图2-2显示了这样一个系统的组成部分。