1、專業好文檔三、讀圖分析： 一、圖為單向起動反接制動控制線路。此電路采用速度繼電器來檢測電動機轉速的變化。在1203000rpm。范圍內速度繼電器觸頭動作，當轉速低于100 rpm時；其觸頭復位、圖中km1為單向旋轉接觸器，km2為反接制動接觸器，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：起動時按下sb2，km1通電并自鎖，電動機運轉，當轉速上升到120rpm以上時，速度繼電器ks的常開觸頭閉合，為反接制動做準備當按下停止復合按鈕時，sb1常閉觸點先斷開，km1斷電，電動機脫離電源，靠慣性繼續高速旋轉，ks常開觸頭仍閉合當sb1常開閉合后，km2通電井自鎖，電動機串接電阻接反相序

2、電源電動機進人反接制動狀態，轉速迅速下降當電動機轉速降到低于100rpm時，速度繼電器ks的常開觸點復位，km 2斷電，反接制動結束電動機脫離電源后自然停車。二、如圖所示為y一降壓起動控制線路，試分析其工作過程，并說明kmy與km的常閉觸點的作用。答：kmy與km的常閉觸點是保證接觸器kmy與km不會同時通電，以防電源短路（3分）km的常閉觸點同時也使時間繼電器kt斷電（起動后不需要kt得電）（3分）。三、下圖所示為異步電動機的能耗制動控制線路，試分析該電路的工作過程答：按下啟動按鈕sb2-接觸器km1通電并自鎖，主電路中的常開觸點閉合，電動機啟動。答案（4分）四、 下圖所示為三相鼠箱式異步電

3、動機串電阻起動控制線路，說明電路中fu和fr的作用，并分析該電路的起動過程km2的作用？ 答：fu起短路保護作用（4分）fr起過載保護作用（4分）。該電路的起動過程如下按下起動按鈕sb2，接觸器km1得電并自鎖，主電路中km1的常開主觸點閉合，電動機串電阻降壓起動，同時時間繼電器kt也得電。當kt的延時時間到了以后，其通電延時閉合的觸點閉合，使接觸器km2得電并自鎖，km2的常閉觸點斷開，km1和kt均斷電，主電路中km1的常開主觸點斷開，km2的常開主觸點閉合，電阻r被短路掉，電動機常壓運行（6分）五、下圖所示為兩臺電動機的電氣控制線路，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現的答： fu是起短路保護的熔斷器（5分）fr是起過載保護作用的熱繼電器（5分）。電路的工作過程如下：合上刀開關q按下起動按鈕sb3，接觸器km1的線圈得電并自鎖，主電路中其常開觸點閉合，電動機m1起動。按下起動按鈕sb2，接觸器km2的線圈得電并自鎖，主電路中其常開觸點閉合，電動機m2起動。sb2是電動機m2的停止按鈕，按下它，接觸器km2的線圈斷電，電動機m2停止。sb1是總停止按鈕，按下它，電動機m1和電動機m2均停止，此電路中，將接觸器km1的一個常開觸點串聯在接觸器km2的線圈電路中，保證只有當電動機m1起動后，電動機m2才能起動，即

5、實現了聯鎖功能。（l0分）六、下圖為兩個電動機控制線路。試分析該線路的工作過程。km2m13m23km3fr1fr2km1qu v wfu1fu2sb2km3km1km3sb1km2km2sb4km2km1km1km2sb3km3km3km1fr1fr2答：m1電動機能夠正、反轉；m2電動機單方向運轉。兩個電動機互鎖。電動機都有熔斷器和熱繼電器保護。讀圖分析(共20分) 下圖所示為機床工作臺自動往復行程控制的電路，行程開關st1、st2分別裝在機床床身的兩側需要返回的位置，擋鐵裝在工作臺上。試分析該電路的工作過程，并說明行程開關st3、st4以及接觸器km，和km2的常閉觸點的作用四圖(5)所

6、示為三相鼠籠式異步電動機串電阻起動控制線路，說明 、 電路中fu和fr的作用，并分析該電路的起動過程。(20分)按下起動按鈕sb2接觸器km1得電，電源通過電阻r加到電動機定子繞組上，降壓起動(7分)。由時間繼電器控制其降壓起動的時間，時間繼電器延時時間一到，其常開觸點閉合，使接觸器km1的線圈得電，同時接觸器km1和kt的線圈失電，電阻r從電網中切除，電動機在正常電壓下運行(7分)。fu是熔斷器，起短路保護作用；fr是熱繼電器，起長期過載保護作用。(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