單相和三相交流電.ppt

1、Unit Four,1.SINGLE-PHASE AND THREE- PHASE AC 單相和三相交流電 2.RLC SERIES CIRCUIT RLC 串聯(lián)電路 3.RESONANCE 諧振,1. SINGLE-PHASE AND THREE-PHASE AC 單相和三相交流電,1. Words： generator n.發(fā)電機(jī)，發(fā)生器，（計）生成程序gengrate vt. 產(chǎn)生,發(fā)生 hot wire 火線=power line; neutral wire 中線 =null line 零線 electrical shock 觸電 distribute v.分配,分發(fā)distribut

2、able a.可分配的,可分類的,如: income 可分配收入 power plants 發(fā)電機(jī) be similar to 相似的,相當(dāng)于,1.Sentence This voltage is similar to three single-phase sine waves separated in phase by 120. (三相)電壓相當(dāng)于三個相位差各為120度的單相正弦波電壓(疊加).,2.Words in phase 同相 out of phase 異相,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, 二級的, 中級的, 第二的 hp 馬力 =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. 幾乎所有的電

4、能都是以三相交流電的形式被生產(chǎn)和長距離傳輸?shù)?為產(chǎn)生三相電壓,三個線圈分成120度布置在電機(jī)中.,4.Words advantage pulsate v. 脈動 one-cylinder n.單缸 multicylinder 多缸 gas engine 汽油發(fā)動機(jī),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. 單獨(dú)一個相的功率是脈動的,但總功率

5、比較恒定.三相交流電的峰值電壓相隔120度.,5.Words rating n.額定值,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.電阻的;capacitive a. 電容的;reactive a.電抗的 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.附屬,關(guān)于,適合 individual a.個人的,個體的,單獨(dú)的 n. 個人.個體 characteristic n.特性 , 特點(diǎn),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. 當(dāng)兩種本質(zhì)上特性

9、相反的電抗元件如電容和電感串聯(lián)時,將會對總的電壓和電流產(chǎn)生影響.,2.Words common reference n. 公共參考 represent v.代表 ,如:be ed by phasor n.向量 respective a. 分別的,各自的=personal/individual,2.Question Current is the common reference for RLC series circuit , why?,3.Words summation n.總和summate v. 求之和 difference n.差額,差別,a. 微分的,差動的integral n.積分

10、lag n.落后 a.最后的 v.滯后;lead n. 如:reactance,純電抗 radical sign 根號,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 底邊 the altitude 高 the hypotenuse 斜邊,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 確定 malfuction 機(jī)器發(fā)生故障 Identification 辨認(rèn)，鑒別，證明 Fashion 流行，樣式 Specialis

13、t 專家 Isolate 離析,3.RESONANCE,1.Two-way radio 雙向無線電 2.open;short短路 infinite 無窮大 3.exact value 具體值 abbreviate 簡寫成,HOME WORKS,P40,Stage 2, Write a paragraph! P41,Reading and TranslatingRESONANCE!,4.USING AN OSCILLOSCOPE,1.service 服務(wù)，應(yīng)用；observe 觀察 2.phosphorescent 熒光的 3.Intensity 亮度 focus 調(diào)焦 vertical pos

14、ition 縱向位置 horizontal position 水平位置 vertical gain 縱向增益 vertical attenuation 縱向衰減 horizontal sweep 水平掃描 synchronization select 同步選擇,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