Unit Four
1.SINGLE-PHASE AND THREE-
PHASE AC
单相和三相交流电
2.RLC SERIES CIRCUIT
RLC 串联电路
3.RESONANCE
谐振
1. SINGLE-PHASE AND THREE-PHASE AC
单相和三相交流电
1. Words:
generator n.发电机,发生器,(计)生成程序gengrate vt. 产生,发生
hot wire 火线=power line; neutral wire 中线 =null line 零线
electrical shock 触电
distribute v.分配,分发distributable a.可分配的,可分类的,如:~ income 可分配收入
power plants 发电机
be similar to 相似的,相当于
1.Sentence
This voltage is similar to three single-phase sine waves separated in phase by 120.
(三相)电压相当于三个相位差各为120度的单相正弦波电压(叠加).
2.Words
in phase 同相
out of phase 异相,相位差
2 .Question
What is phase ,in phase and out of phase?
3.Words
primarily ad. 首先,主要,根本上地primary a.第一位的, 主要的, 初步的, 根源的(反)secondary a.次要的, 二级的, 中级的, 第二的
hp 马力 =horsepower
3.Sentence
Almost all electrical power is generated and transmitted over long distances as three-phase ac.Three coils are placed 120 apart in a generator to produce three-phase voltage.
几乎所有的电能都是以三相交流电的形式被生产和长距离传输的.为产生三相电压,三个线圈分成120度布置在电机中.
4.Words
advantage
pulsate v. 脉动
one-cylinder n.单缸
multicylinder 多缸
gas engine 汽油发动机
4.Sentence
The power of one separate phase is pulsating, but the total power is more constant.The peak values of three-phase ac are separated by 120.
单独一个相的功率是脉动的,但总功率比较恒定.三相交流电的峰值电压相隔120度.
5.Words
rating n.额定值
DO EXERCISE!Comprehension Questions,then I’ll select some of you to answer it.
1.It is made up of a hot wire and a neutral wire.
2.It is made up of three power lines.
3.In order to prevent electrical shocks.
4.By three-phase generators at power plants.
5.It’s used to power large equipment in industry and commercial buildings.
6.It is used at homes.
DO EXERCISE!Comprehension Questions,then I’ll select some of you to answer it.
7.It refers to time or the difference between one point and another.
8.Three-phase ac is.
9.Three-phase ac is. Because it’s steady and its peak values are separated only by 120.
10.It is almost 50%larger.
11.It’s 3v because three-phase voltage is a combi-nation of three single-phase voltages.
2.RLC SERIES CIRCUIT
1.Words
resistive a.电阻的;capacitive a. 电容的;reactive a.电抗的
element a. 元素,元件,如:adding ~加法元件component n.成分,部件,元件,如:electrical ~
pertain v.附属,关于,适合
individual a.个人的,个体的,单独的 n. 个人.个体
characteristic n.特性 , 特点
1.Sentence
This pertains to the effect on total line voltage and current when connecting reactive elements in series,whose individual characteristics are opposite in nature,such as inductance and capacitance.
当两种本质上特性相反的电抗元件如电容和电感串联时,将会对总的电压和电流产生影响.
2.Words
common reference n. 公共参考
represent v.代表 ,如:be ~ed by
phasor n.向量
respective a. 分别的,各自的=personal/individual
2.Question
Current is the common reference for RLC series circuit , why?
3.Words
summation n.总和summate v. 求…之和
difference n.差额,差别,a. 微分的,差动的integral n.积分
lag n.落后 a.最后的 v.滞后;lead n.&v.超前
3.Question
When will line voltage and current be in phase?
4.Words
prior to 在…之前
operation n.运算,操作,行动
impedance阻抗the total opposition to current flow
reactance电抗Opposition to the flow of alternating current caused by the inductance and capacitance in a circuit rather than by resistance.
net 纯粹的 ; 如:~reactance,纯电抗
radical sign 根号
4.Question
Can you tell me how to compute the impe-dance in RLC series circuit?
5.Words
phasoral layout 向量排列法
the base 底边
the altitude 高
the hypotenuse 斜边
6.Question
What does resonance mean?
DO EXERCISE A!
1.It has an effect on total line voltage.
2.Their individual characteristics are unchanged
3.Current is commonly is used as an reference.
4.They will be in phase.
5.The difference of XL and XC must be determined.
6.It is the Pythagorean Theorem-based formula, phasoral layout and triangulation.
7.It represents total impedance.
8.It refers to the fact that XL and XC are equal, and line voltage and current are in phase.
DO EXERCISE B!
triangulation
Impedance
reactive
capacitors
inductive
Resistive
magnetic
electromotive
DO EXERCISE C!
Troubleshoot 故障查找
identify 确定
malfuction 机器发生故障
Identification 辨认,鉴别,证明
Fashion 流行,样式
Specialist 专家
Isolate 离析
3.RESONANCE
1.Two-way radio 双向无线电
2.open;short短路
infinite 无穷大
3.exact value 具体值
abbreviate 简写成
HOME WORKS
P40,Stage 2, Write a paragraph!
P41,Reading and Translating—RESONANCE!
4.USING AN OSCILLOSCOPE
1.service 服务,应用;observe 观察
2.phosphorescent 荧光的
3.Intensity 亮度
focus 调焦
vertical position 纵向位置
horizontal position 水平位置
vertical gain 纵向增益
vertical attenuation 纵向衰减
horizontal sweep 水平扫描
synchronization select 同步选择
4.USING AN OSCILLOSCOPE
GUIDED WRITING
After day’s work in the lab,two scientists are coming to the end of their experiment.But before they go home, there are a lot of things that have to be done. The heater is still working, it needs to be turned off.The electrician’s tools are every where on the floor and have to be put in place.The dirty floor has to be mopped(用拖把拖洗).Precise instruments on the working table must be covered.It is dangerous to let the electric stove still burn when nobody is in the lab.So it must be remembered to unplug it.The fire alarm system must be plugged into an out-let in case a fire breaks out. All the lamps have to be turned off and of course the door has to be closed.The scientists must be exhausted after doing all the work.
END