電大機(jī)械本科機(jī)電控制與可編程控制器技術(shù)分析復(fù)習(xí)題小抄參考

1、專業(yè)好文檔三、讀圖分析： 一、圖為單向起動(dòng)反接制動(dòng)控制線路。此電路采用速度繼電器來檢測(cè)電動(dòng)機(jī)轉(zhuǎn)速的變化。在1203000rpm。范圍內(nèi)速度繼電器觸頭動(dòng)作，當(dāng)轉(zhuǎn)速低于100 rpm時(shí)；其觸頭復(fù)位、圖中km1為單向旋轉(zhuǎn)接觸器，km2為反接制動(dòng)接觸器，ks為速度繼電器，r為反接電阻、試分析該線路的工作過程答：起動(dòng)時(shí)按下sb2，km1通電并自鎖，電動(dòng)機(jī)運(yùn)轉(zhuǎn)，當(dāng)轉(zhuǎn)速上升到120rpm以上時(shí)，速度繼電器ks的常開觸頭閉合，為反接制動(dòng)做準(zhǔn)備當(dāng)按下停止復(fù)合按鈕時(shí)，sb1常閉觸點(diǎn)先斷開，km1斷電，電動(dòng)機(jī)脫離電源，靠慣性繼續(xù)高速旋轉(zhuǎn)，ks常開觸頭仍閉合當(dāng)sb1常開閉合后，km2通電井自鎖，電動(dòng)機(jī)串接電阻接反相序

2、電源電動(dòng)機(jī)進(jìn)人反接制動(dòng)狀態(tài)，轉(zhuǎn)速迅速下降當(dāng)電動(dòng)機(jī)轉(zhuǎn)速降到低于100rpm時(shí)，速度繼電器ks的常開觸點(diǎn)復(fù)位，km 2斷電，反接制動(dòng)結(jié)束電動(dòng)機(jī)脫離電源后自然停車。二、如圖所示為y一降壓起動(dòng)控制線路，試分析其工作過程，并說明kmy與km的常閉觸點(diǎn)的作用。答：kmy與km的常閉觸點(diǎn)是保證接觸器kmy與km不會(huì)同時(shí)通電，以防電源短路（3分）km的常閉觸點(diǎn)同時(shí)也使時(shí)間繼電器kt斷電（起動(dòng)后不需要kt得電）（3分）。三、下圖所示為異步電動(dòng)機(jī)的能耗制動(dòng)控制線路，試分析該電路的工作過程答：按下啟動(dòng)按鈕sb2-接觸器km1通電并自鎖，主電路中的常開觸點(diǎn)閉合，電動(dòng)機(jī)啟動(dòng)。答案（4分）四、 下圖所示為三相鼠箱式異步電

3、動(dòng)機(jī)串電阻起動(dòng)控制線路，說明電路中fu和fr的作用，并分析該電路的起動(dòng)過程km2的作用？ 答：fu起短路保護(hù)作用（4分）fr起過載保護(hù)作用（4分）。該電路的起動(dòng)過程如下按下起動(dòng)按鈕sb2，接觸器km1得電并自鎖，主電路中km1的常開主觸點(diǎn)閉合，電動(dòng)機(jī)串電阻降壓起動(dòng)，同時(shí)時(shí)間繼電器kt也得電。當(dāng)kt的延時(shí)時(shí)間到了以后，其通電延時(shí)閉合的觸點(diǎn)閉合，使接觸器km2得電并自鎖，km2的常閉觸點(diǎn)斷開，km1和kt均斷電，主電路中km1的常開主觸點(diǎn)斷開，km2的常開主觸點(diǎn)閉合，電阻r被短路掉，電動(dòng)機(jī)常壓運(yùn)行（6分）五、下圖所示為兩臺(tái)電動(dòng)機(jī)的電氣控制線路，a）為主電路，b）為控制電路。試說明fu和fr的作用分

4、析此電住的工作原通（過程）并說明出連鎖功能是知何實(shí)現(xiàn)的答： fu是起短路保護(hù)的熔斷器（5分）fr是起過載保護(hù)作用的熱繼電器（5分）。電路的工作過程如下：合上刀開關(guān)q按下起動(dòng)按鈕sb3，接觸器km1的線圈得電并自鎖，主電路中其常開觸點(diǎn)閉合，電動(dòng)機(jī)m1起動(dòng)。按下起動(dòng)按鈕sb2，接觸器km2的線圈得電并自鎖，主電路中其常開觸點(diǎn)閉合，電動(dòng)機(jī)m2起動(dòng)。sb2是電動(dòng)機(jī)m2的停止按鈕，按下它，接觸器km2的線圈斷電，電動(dòng)機(jī)m2停止。sb1是總停止按鈕，按下它，電動(dòng)機(jī)m1和電動(dòng)機(jī)m2均停止，此電路中，將接觸器km1的一個(gè)常開觸點(diǎn)串聯(lián)在接觸器km2的線圈電路中，保證只有當(dāng)電動(dòng)機(jī)m1起動(dòng)后，電動(dòng)機(jī)m2才能起動(dòng)，即

5、實(shí)現(xiàn)了聯(lián)鎖功能。（l0分）六、下圖為兩個(gè)電動(dòng)機(jī)控制線路。試分析該線路的工作過程。km2m13m23km3fr1fr2km1qu v wfu1fu2sb2km3km1km3sb1km2km2sb4km2km1km1km2sb3km3km3km1fr1fr2答：m1電動(dòng)機(jī)能夠正、反轉(zhuǎn)；m2電動(dòng)機(jī)單方向運(yùn)轉(zhuǎn)。兩個(gè)電動(dòng)機(jī)互鎖。電動(dòng)機(jī)都有熔斷器和熱繼電器保護(hù)。讀圖分析(共20分) 下圖所示為機(jī)床工作臺(tái)自動(dòng)往復(fù)行程控制的電路，行程開關(guān)st1、st2分別裝在機(jī)床床身的兩側(cè)需要返回的位置，擋鐵裝在工作臺(tái)上。試分析該電路的工作過程，并說明行程開關(guān)st3、st4以及接觸器km，和km2的常閉觸點(diǎn)的作用四圖(5)所

6、示為三相鼠籠式異步電動(dòng)機(jī)串電阻起動(dòng)控制線路，說明 、 電路中fu和fr的作用，并分析該電路的起動(dòng)過程。(20分)按下起動(dòng)按鈕sb2接觸器km1得電，電源通過電阻r加到電動(dòng)機(jī)定子繞組上，降壓起動(dòng)(7分)。由時(shí)間繼電器控制其降壓起動(dòng)的時(shí)間，時(shí)間繼電器延時(shí)時(shí)間一到，其常開觸點(diǎn)閉合，使接觸器km1的線圈得電，同時(shí)接觸器km1和kt的線圈失電，電阻r從電網(wǎng)中切除，電動(dòng)機(jī)在正常電壓下運(yùn)行(7分)。fu是熔斷器，起短路保護(hù)作用；fr是熱繼電器，起長(zhǎng)期過載保護(hù)作用。(6分)winger tuivasa-sheck, who scored two tries in the kiwis 20-18 semi-fi

7、nal win over england, has been passed fit after a lower-leg injury, while slater has been named at full-back but is still recovering from a knee injury aggravated against usa.both sides boast 100% records heading into the encounter but australia have not conceded a try since josh charnleys effort in

8、 their first pool match against england on the opening day.aussie winger jarryd hayne is the competitions top try scorer with nine, closely followed by tuivasa-sheck with eight.but it is recently named rugby league international federation player of the year sonny bill williams who has attracted the

9、 most interest in the tournament so far.the kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the world cup in both rugby league and rugby union after triumphing with the all blacks in 2011.id give every award back in a heartbeat just to get across the li

10、ne this weekend, said williams.the (lack of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier league match at chelsea on sunday.i am going to be at the match

11、 tomorrow and i have asked to meet yaya toure, he told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, pres

12、ident of european footballs governing body, has also ordered an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist insults from fans of cska. baumgartner the disappointing new

13、s: mission aborted.the supersonic descent could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. the balloon, with capsule attached

14、, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the

15、 stratosphere. as he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembling an olympic diving platform.they blew it in 2008 when t

16、hey got caught cold in the final and they will not make the same mistake against the kiwis in manchester.five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by englands josh charnley in the opening game of the tournamen

17、t.that could be classed as a weakness, a team under-cooked - but i have been impressed by the kangaroos focus in their games since then.they have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good

18、 kick-chase. theyve been great at all the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.it is as though their entire tournament has been preparation for the final.in johnathan thurston, cooper cronk, cameron smith and either billy slater or greg inglis at full-back they have a spine that is unmatched in rugby league. they have played in so many high-pressure games - a priceless as