单相和三相交流电.ppt

1、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distribut

2、able 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.Wor

3、ds 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

4、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

5、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 Ill 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

6、s used to power large equipment in industry and commercial buildings. 6.It is used at homes.,DO EXERCISE!Comprehension Questions,then Ill 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 its steady

7、 and its peak values are separated only by 120. 10.It is almost 50%larger. 11.Its 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:electr

8、ical 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

9、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

10、lag n.落后 a.最后的 v.滞后;lead n. 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

11、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

12、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 Specialis

13、t 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 TranslatingRESONANCE!,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 pos

14、ition 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 days work in the lab,two scientists are coming to the end of their experiment.But before they go home, there are a lot of th

15、ings that have to be done. The heater is still working, it needs to be turned off.The electricians 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 remem