異步電動(dòng)機(jī)新

異步電動(dòng)機(jī)介紹教學(xué)目標(biāo)知道單相異步電動(dòng)機(jī)的應(yīng)用了解單相異步電動(dòng)機(jī)的結(jié)構(gòu)簡(jiǎn)單分析單相異步電動(dòng)機(jī)的工作原理分析單相異步電動(dòng)機(jī)的控制分析單相異步電動(dòng)機(jī)的維護(hù)和修理知識(shí)情感目標(biāo)異步電動(dòng)機(jī)的分類按定子相數(shù)可分為三相、單相、兩相異步電動(dòng)機(jī)三類。兩相異步電動(dòng)機(jī)主要應(yīng)用于微型控制電機(jī)三相異步電動(dòng)機(jī)主要應(yīng)用于現(xiàn)代動(dòng)力用電動(dòng)機(jī)單相異步電動(dòng)機(jī)主要應(yīng)用于200W以下的電機(jī)2.接法：這是指定子三相繞組的接法。一般鼠籠式電動(dòng)機(jī)的接線盒中有六根引出線,標(biāo)有U1、V1、W1、U2、V2、W2。其中：U1U2是第一相繞組的兩端；V1V2是第二相繞組的兩端；W1W2是第三相繞組的兩端。如果U1、V1、W1分別為三相繞組的始端(頭)，則U2、V2、W2是相應(yīng)的末端(尾)。這六個(gè)引出線端在接電源之前,相互間必須正確聯(lián)接。聯(lián)接方法有星形(Y)聯(lián)接和三角形()聯(lián)接兩種(下圖所示)。通常三相異步電動(dòng)機(jī)自3kW以下者,聯(lián)接成星形;自4kW以上者,聯(lián)接成三角形

3.額定功率PNPN：是指電動(dòng)機(jī)在制造廠所規(guī)定的額定情況下運(yùn)行時(shí),其輸出端的機(jī)械功率,單位一般為千瓦（kW）。對(duì)三相異步電機(jī)，其額定功率：PN=UNINηNcosN式中ηN和cosN分別為額定情況下的效率和功率因數(shù)。

4.額定電壓UN：

是指電動(dòng)機(jī)額定運(yùn)行時(shí),外加于定子繞組上的線電壓,單位為伏（V）。線電壓為380V時(shí),電動(dòng)機(jī)繞組為星形聯(lián)接；電源線電壓為220V時(shí),電動(dòng)機(jī)繞組為三角形聯(lián)接)。5.額定電流IN：IN是指電動(dòng)機(jī)在額定電壓和額定輸出功率時(shí),定子繞組的線電流,單位為安（A）。

當(dāng)電動(dòng)機(jī)空載時(shí),轉(zhuǎn)子轉(zhuǎn)速接近于旋轉(zhuǎn)磁場(chǎng)的同步轉(zhuǎn)速,兩者之間相對(duì)轉(zhuǎn)速很小,所以轉(zhuǎn)子電流近似為零,這時(shí)定子電流幾乎全為建立旋轉(zhuǎn)磁場(chǎng)的勵(lì)磁電流。當(dāng)輸出功率增大時(shí),轉(zhuǎn)子電流和定子電流都隨著相應(yīng)增大,如下圖中的I1=f(P2)曲線所示。圖中是一臺(tái)l0kW三相異步電動(dòng)機(jī)的工作特性曲線。6.額定頻率

fN：我國(guó)電力網(wǎng)的頻率為50赫茲（Hz），因此除外銷產(chǎn)品外,國(guó)內(nèi)用的異步電動(dòng)機(jī)的額定頻率為50赫茲。

7.額定轉(zhuǎn)速nN

是指電動(dòng)機(jī)在額定電壓、額定頻率下,輸出端有額定功率輸出時(shí),轉(zhuǎn)子的轉(zhuǎn)速,單位為轉(zhuǎn)/分(r/min)。由于生產(chǎn)機(jī)械對(duì)轉(zhuǎn)速的要求不同,需要生產(chǎn)不同磁極數(shù)的異步電動(dòng)機(jī),因此有不同的轉(zhuǎn)速等級(jí)。最常用的是四個(gè)極的異步電動(dòng)機(jī)(n0=l500r/min)。

8.額定效率ηN

是指電動(dòng)機(jī)在額定情況下運(yùn)行時(shí)的效率,是額定輸出功率與額定輸入功率的比值。即ηN=×100%=×100%異步電動(dòng)機(jī)的額定效率ηN約為75%～92%。從下圖中的η=f(P2)曲線可以看出，在額定功率的75%左右時(shí)效率最高.9.額定功率因數(shù)cosN

額定功率因數(shù)：因?yàn)殡妱?dòng)機(jī)是電感性負(fù)載,定子相電流比相電壓滯后一個(gè)角，cos就是異步電動(dòng)機(jī)的功率因數(shù)。絕緣等級(jí)AEBFH極限溫度℃10512013015518011.工作方式

反映異步電動(dòng)機(jī)的運(yùn)行情況，可分為三種基本方式：連續(xù)運(yùn)行、短時(shí)運(yùn)行和斷續(xù)運(yùn)行。

三相異步電動(dòng)機(jī)的額定值刻印在每臺(tái)電動(dòng)機(jī)的銘牌上,一般包括下列幾種：

1.型號(hào)：為了適應(yīng)不同用途和不同工作環(huán)境的需要，電動(dòng)機(jī)制成不同的系列,每種系列用各種型號(hào)表示。例如Y132M-4Y→三相異步電動(dòng)機(jī)，其中三相異步電動(dòng)機(jī)的產(chǎn)品名稱代號(hào)還有：YR為繞線式異步電動(dòng)機(jī)；YB為防爆型異步電動(dòng)機(jī)；YQ為高起動(dòng)轉(zhuǎn)距異步電動(dòng)機(jī)。132→機(jī)座中心高(mm)M→機(jī)座長(zhǎng)度代號(hào)

4→磁極數(shù)

單相異步電動(dòng)機(jī)是利用單相交流電源供電，其轉(zhuǎn)速隨負(fù)載變化略有變化的一種小容量交流電機(jī)。具有結(jié)構(gòu)簡(jiǎn)單、價(jià)格低廉、維修方便的特點(diǎn)，在工、農(nóng)業(yè)生產(chǎn)、辦公場(chǎng)所、家用電器等方面得到廣泛的應(yīng)用。如：吊扇、洗衣機(jī)、電冰箱、電鉆、小型機(jī)床等。3.1單相異步電動(dòng)機(jī)的應(yīng)用壁扇電機(jī)臺(tái)扇電機(jī)轉(zhuǎn)頁扇電機(jī)全自動(dòng)洗衣機(jī)電機(jī)洗衣機(jī)用脫水電機(jī)3.2單相異步電動(dòng)機(jī)的結(jié)構(gòu)單相異步電動(dòng)機(jī)定子上一般有兩個(gè)繞組：起動(dòng)繞組、工作繞組，兩繞組在空間上相距90度電角度。轉(zhuǎn)子是籠型結(jié)構(gòu)。起動(dòng)繞組只在起動(dòng)時(shí)接入，起動(dòng)完畢從電源斷開。單相異步電動(dòng)機(jī)如果直接接正弦交流電，將產(chǎn)生脈振磁動(dòng)勢(shì)。一個(gè)脈振磁動(dòng)勢(shì)可分解為兩個(gè)轉(zhuǎn)向相反的旋轉(zhuǎn)磁動(dòng)勢(shì)，因此，單相異步電動(dòng)機(jī)不能自行起動(dòng)。3.3單相異步電動(dòng)機(jī)的工作原理3.4單相異步電動(dòng)機(jī)的控制1．家用電風(fēng)扇控制電路2．家用洗衣機(jī)控制電路3．家用電冰箱控制電路3.5單相異步電動(dòng)機(jī)的維護(hù)和修理3.4.1單相異步電動(dòng)機(jī)的拆裝1．常用電機(jī)拆卸和修理工具木錘拉馬套筒板手繞線機(jī)

起子

鐵錘刮線板1．常用電機(jī)拆卸和修理工具3.4.2單相異步電動(dòng)機(jī)的維護(hù)1．起動(dòng)

2．運(yùn)行3．維修

電動(dòng)機(jī)在起動(dòng)前首先應(yīng)進(jìn)行機(jī)械方面的檢查，然后進(jìn)行電路方面的檢查。電機(jī)的插座前最好安裝熔斷器，熔斷器的額定電流要比電動(dòng)機(jī)的額定電流高10～25％。電動(dòng)機(jī)帶負(fù)載正常運(yùn)轉(zhuǎn)時(shí)轉(zhuǎn)速均勻，聲音適中，發(fā)熱適當(dāng)。但要經(jīng)常注意其溫升情況，如果發(fā)現(xiàn)電動(dòng)機(jī)嚴(yán)重發(fā)熱或其它不良癥狀必需拉閘停止運(yùn)行。電網(wǎng)電壓較低時(shí)經(jīng)常出現(xiàn)發(fā)熱嚴(yán)重的情況，雖然短時(shí)間內(nèi)不會(huì)燒壞繞組，但將影響電動(dòng)機(jī)的使用壽命。

電機(jī)運(yùn)行一段時(shí)間后可以拆開維修，清理內(nèi)部雜物灰塵，填加潤(rùn)滑油等；最好用500伏級(jí)搖表測(cè)量繞組絕緣電阻，正常的應(yīng)不小于0.5兆歐。

3.4.3單相異步電動(dòng)機(jī)的修理1．起動(dòng)故障的修理2．運(yùn)行故障的修理ThankYou![Imageinformationinproduct]Image:www.photosclub.co.kr/CD_GlobalBusiness&communication(ImageStates)Notetocustomers:ThisimagehasbeenlicensedtobeusedwithinthisPowerPointtemplateonly.Youmaynotextracttheimageforanyotheruse.HowdoIincorporatemylogotoaslidethatwillapplytoalltheotherslides?Onthe[View]menu,pointto[Master],andthenclick[SlideMaster]or[NotesMaster].Changeimagestotheoneyoulike,thenitwillapplytoalltheotherslides.IntroductionClicktoedittitlestyleAddyourtitleinhereAddyourtitleinhereAddyourtitleinhereThemeGalleryisaDesignDigitalContent&ContentsmalldevelopedbyGuildDesignInc.ThemeGalleryisaDesignDigitalContent&ContentsmalldevelopedbyGuildDesignInc.ThemeGalleryisaDesignDigitalContent&ContentsmalldevelopedbyGuildDesignInc.ThemeGalleryisaDesignDigitalContent&ContentsmalldevelopedbyGuildDesignInc.1.DescribecontentsforaChart

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