电气工程及其自动化专业英语.ppt

Unit 11 The Transformer on No LoadSpecialized English Words
• in close proximity (to) 紧密耦合 • permeability 磁导率 • magnetizing current 激磁电流 • power component of current 电流的有功分量 • sinusoidal variations 正弦变量 • a mutually induced e.m.f. 互感电动势 • the applied voltage 外施电压 • zero-power-factor 零功率因数 • the no-load power factor 空载功率因数 • formulate 用公式表示,系统地阐述 • saturation 饱和
This e.m.f. would drive a load current through any circuit connected to the terminals of the second coil. Energy would then be transferred through the medium of the magnetic field（磁场媒介） from coil 1 to coil 2.
电气工程及其自动化专业英语
Specialized English for Electrical Engineering ＆ Its Automation
戴文进 主 编 杨植新 副主编
Part 2 Electric Machinery
• Unit 11 The Transformer on No Load • Unit 13 Construction and Application of D.C.
• The transformation could be from any convenient input voltage to any convenient output voltage.
• This apparently simple function of the transformer makes it as vital to modern industry as the gear train which, as a “transformer” of speed and torque represents an interesting analogy（句子的主语是“function”，谓语为“make”，“as vital…as”意为“与……一样重要”，“which”引导一个定 语从句“which represents an interesting analogy as a‘transformer’of speed and torque”，修饰“gear train”，意 为“齿轮箱与变压器表现出一种有趣的相似，齿轮箱被称为 速度和转矩的‘变换器’。”
• The coils would be on an iron core (铁芯）and so at the cost of introducing iron losses, the value of flux per ampere is increased several hundred times because of the change of permeability from μ0 to μ0μ r .
• Looked at another way, the leakage flux Φ 1 which links N1 turns alone and “leaks” between the two windings without linking the N2 turns, is a much smaller fraction of the total, making for(有助于, 倾向于) more efficient energy transfer.
Unit 11 The Transformer on No Load
• The Simple Two-Coil Transformer
The transformer is a straightforward application of Faraday's Law of Electromagnetic Induction. The simple transformer consists of two coils in close proximity. One coil of N1 turns is excited with alternating current and therefore establishes a flux φ11 which alternates with the current (随时间交变）. The other coil is linked by （与---交链）most of this flux and thus has a mutually induced e.m.f. of value e2=－N2dφ21/dt.
Machines • Unit 16 Three-Phase Induction (Asynchronous)
Machine with the Rotor at Standstill· • Unit 19 Armature Reaction of Salient-Pole
Synchronous Machine a Two-Reaction Theory
Biblioteka Baidu
• The exciting or magnetizing current （励磁电流）can thus be very small. Further, the proportion of the total flux which is linked mutually by the two coils is greatly increased.