电气工程及其自动化专业英语复习资料

1.1.1 We consider the flow of electric charges. A unique feature of electric charge or electricity is the fact that it is mobile; that is, it can be transferred from one place to another, where it can be converted to another form of energy.
我们认为电荷是流动的。

电荷和电的特点是它具有流动性；即它可以从一个地方转移到另一个地方，在转移的过程中，电荷或电能转变为另一种形式的能量。

1.1.2 The power absorbed or supplied by an element is the product of the voltage across the element and the current through it.
一个元件吸收或者发出的功率是元件两端的电压和通过该元件的电流的乘积。

1.2.1 We might observe at this point that the polarity marks on Fig.1-4(b) are redundant since the polarity could be defined by the positions of the longer and shorter lines.
大家或许注意到图1-4(b)所标注的极性是多余的。

因为恒压源的极性可以用长线、短线来定义。

1.2.2 It should be noted that an ideal voltage source (dependent or independent) will produce any current required to ensure that the terminal voltage is as stated, whereas an ideal current source will produce the necessary voltage to ensure the stated current flow.
应该注意一个理想电压源，(独立和受控)可向电路提供任意电流，以保证其端电压为规定值，而理想电流源，可向电路提供任意电压以保证其规定电流。

1.4.1 Still anther class of relationship is one between several variables of the same type which occurs as the result of the network configuration, i.e., the manner in which the various element of the network are interconnected.
另一类关系由于网络结构，即网络的不同元件互相连接的方式所产生的相同形式的一些变量间的关系。

1.4.2 Kirchhoff’s Current Law is based on the law of conservation of charge, which requires that the algebraic sum of charges within a system can not change.
基尔霍夫电流定律基于电荷守恒定律，要求一个系统内电荷的代数和不变。

1.5.1 Since a voltage is defined as existing between two nodes, it is convenient to select one node in the network to be a reference node or datum node and then associate a voltage or a potential with each of the other nodes.
由于电压定义为两个节点之间的相对变量，一个方便的做法是选择网络中的一个节点作为参考节点或基准节点，从而确定其他所有节点的电压和电位。

1.5.2 Mesh analysis is not quite as general as nodal analysis because it is only applicable to a circuit is planar.
由于网孔分析法仅适用于平面电路，故网孔分析法不像节点分析法那样通用。

1.6.1 We can proceed to our simplification of sinusoidal steady-state analysis by establishing the relationship between the phasor voltage and phasor current for each of the three passive elements.
通过建立三种无源元件各自的电压相量和电流相量之间的关系，我们可以对正弦稳态分析进行简化。

1.6.2 On the other hand, delta-connected sources are not common in practice because of the circulating current that will result in the delta-mesh if the three-phase voltage are slightly unbalanced.
另一方面，实际中三角形连接的电源并不常用，因为三相电压稍有不平衡就会在三角形连接的网孔中产生循环电流。

2.1.1 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.
在日益发展的科技社会中，的每一方面，无论是科学，工程，医学，音乐，维修，甚至是谍报，电子学的作用都是非常大的，而且越来越重要。

2.1.2 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 the stock market transactions.
这种信息或许像无线广播的演讲和音乐，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。

2.2.1 Boole and others were interested in developing a systematic means of deciding whether proposition in logic or mathematics was true or false, but we shall be concerned only with validity of the output of digital devices.
布尔和其他研究者致力于发展一种证明逻辑上或数学中命题的真假问题的系统方法，而我们只关心数字设备输出的正确性。

3.1.1 Assume that initially the switch is on, hence, the current through the switch is I s. The capacitor voltage is U o, the voltage across the switch is zero and the diode V1 is reverse biased.假设开始时开关处于闭合状态，则通过开关的电流为Is，电容器的电压为Ug，开关两端的电压为零，二极管V1反向偏置
3.2.1 It must, however, be kept in mind that a step-down voltage converter is also a step-up current converter and vice versa because the input power must equal the output power.
因为输入功率必须等于输出功率，必须牢记降压电压变换器也是升流的电流变换器，反之亦然。

3.2.2 A prominent application of the Buck converter is a DC regulated power supply in which the output voltage is regulated against the variations in the load resistance and the input voltages.降压式变换器的一个著名应用是用于直流可调电源，调整其输出电压以补偿负荷电阻和输入电压的变化。

4.1.1 Whereas the copper disk will rotate in the same direction as the rotating magnetic field, it will never reach the same speed as the rotating magnet, because if it did, would be no relative motion between the two and therefore no current induced in the copper disk.
尽管铜盘将以与旋转磁场方向相同的方向转动，但它却达不到旋转磁场的转速。

因为如果铜盘达到了旋转磁场的转速，它们之间就没有相对运动，那么铜盘中就不会产生感应电流。

4.1.2 The sizes at which the transition between cast-aluminum and copper rotors takes place varies among rotor manufacturers, but virtually all rotors in motor sizes of several thousand horsepower and above are built with bar-type rotors.
多大容量的机组使用铜条，多大容量的机组采用铸铝，这要由转子制造厂家决定，实际上容量为几千及以上马力的电动机都制造成铜条式转子。

4.2.1 Synchronous speed, defined in (4-2) and designated as Ns in Fig.4-3, is the speed at which the rotor is revolving in synchronism with the rotating magnetic field generated by the stator windings, and there is therefore no rotor current and no electrically generated torque.
由式(4-2)定义并在图4-3中用Ns表示的同步转速，是转子以与定子绕组产生的旋转磁场相同的速度同步旋转的速度，因此没有转子电流和电磁转矩。

4.2.2 The locked-rotor torque Tl in Fig.4-3 is the torque produced by the motor at zero speed and is important because this is the torque that must overcome any breakaway forces imposed by the load.
图4-3中的锁定转子转矩Tl是电动机在零转速时产生的转矩，由于它必须克服由负载带来的任何起动阻力，因此非常重要。

4.3.1 At synchronous speed, the rotating magnetic field created by the armature currents travels at the same speed as the field created by the field current, and a steady torque results.
由电枢电流产生的旋转磁场与由励磁电流产生的磁场均以同步转速旋转，产生一个稳定的转矩。

4.3.2 Because of the economies of high-speed high-temperature high-pressure steam turbines, much study and some real pioneering work have been devoted to improvements in materials and design of both generators and turbines, and the maximum ratings for which 3600-rpm machines have been built have approximately doubled before the decade.
由于高速高温高压汽轮机的经济性，许多研究和一些富有开拓性的工作已改进了发电机和汽轮机的材料与设计，转速为3600rpm的电机的最大容量较十年前已接近翻一番。

4.3.3 The cooling problem in electrical apparatus in general increases in difficulty with increasing size, because the surface area from which the heat must be carried away increases roughly as the square of the dimensions, while the heat developed by the losses is roughly proportional to the volume and therefore increases approximately as the cube of the dimensions.
一般而言随着设备容量的增大电气设备中冷却问题也更为困难，主要是因为热交换需要散热面积随外形尺寸的平方而增大，而损耗产生的热量与设备的体积成比例，即近视地随外形尺寸的立方增大而增大。

4.4.1 A power transformer also produces a secondary voltage directly proportional to its primary voltage; the difference between a potential transformer and a power transformer is that the potential transformer is designed to handle only a very small current.
电力变压器也可以输出一个直接与一次电压成比例的二次电压，电压互感器与电力变压器的区别是电压互感器仅能处理非常小的电流。

4.4.2 The magnetization current Im is a current proportional (in the unsaturated region) to the voltage applied to the core, and lagging the applied voltage by 90, so it can be modeled by a reactance Xm connected across the primary voltage source.
磁化电流Im正比与作用于铁芯的电压(在不饱和区域)，并滞后该电压90°，因此可以采用与一次侧的电压源并联的电抗Xm来建模。

6.1.1 This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5km in radius
6.1.2 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.
HVDC可用于远距离大容量输电，也可用于交流系统之间的异步联网，因为交流系统之间可能由于稳定问题和额定频率不同而不能实现交流联网。

6.2.1 Electric power is produced at generating stations (GS) and transmitted to consumers through a complex network of individual components, including transmission lines, transformers, and switching devices.
电能由发电厂生产出来，并通过一个由独立元件组成的复杂网络送给用户，这些元件包括输电线路，变压器和开关设备等。

6.3.1 It should be mentioned that economy of operation is not the only possible consideration.
If the “optimal” economic dispatch requires all the power to be imported from a neighboring utility through a single transmission link, considerations of system security might preclude that solution.
应当指出的是系统运行的经济性不是唯一考虑的因素。

如果最优经济调度要求所有的功率通过单一输电线路从邻近电力公司输入时，从系统安全性方面考虑可能会否决这个方案。

6.3.2 AGC is an effective means for power and frequency control in large-scale power systems. In an interconnected power system, the primary objectives of AGC are to regulate frequency to the specified nominal value and to maintain the interchange power between control areas at the scheduled values by adjusting the output of the selected generators.
AGC是大系统中发电功率和频率控制的有效措施。

在互联电力系统中AGC的主要目标是调整系统的频率到额定值，并且通过调整所选发电机的输出将区域间的功率交换维持在指定值。

7.1.1 However, if due to any reason, say a fault, there is an abnormality, it is necessary that there should be a device which senses these abnormal conditions and if so, the element or component where such an abnormality has taken place is removed, i.e. deleted from the rest of the system as soon as possible.
然而，由于任何原因，比如说故障，系统出现非正常运行状态，就必须有一套装置来感知这种非正常状态，然后将出现非正常状态的元件切除，也就是尽可能快地将该元件与系统其他部分相隔离。

7.1.2 And therefore, if such an abnormality takes place in any element or component is removed from the rest of the system reliably and quickly in order to restore power in the remaining system under the normal condition as soon as possible.
如果异常状态发生在电力网络的任何元件上，受影响的元件应该可靠快速地从系统中切除，以尽快恢复系统正常部分供电。

7.2.1 The cause of overvoltage which ultimately can be due to overspeed of the prime mover, or due to defective voltage regulator, however, these days governors and voltage regulators act very fast and prevent any damage to the winding insulation.
最终导致绝缘破坏的过电压的产生原因可能是由于原动机超速和电压调节器存在缺陷；但是，当今的调速器和电压调节器动作非常快，可以防止过电压对绕组绝缘的损害。