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1、專業(yè)好文檔機(jī)電控制與可編程序控制器技術(shù)課程習(xí)題分析與詳解（一）1隔離開關(guān)和負(fù)荷開關(guān)配合使用時(shí)，對(duì)它們的操作順序有什么規(guī)定？答：分閘：應(yīng)先斷開負(fù)荷開關(guān)，再斷開隔離開關(guān)。合閘：應(yīng)先合上隔離開關(guān)，后合上負(fù)荷開關(guān)。2組合開關(guān)的結(jié)構(gòu)有什么特點(diǎn)？型號(hào)的含義是什么？答：組合開關(guān)由動(dòng)觸片、靜觸片、方形轉(zhuǎn)軸、手柄、定位機(jī)構(gòu)和外殼等部分組成。它的動(dòng)、靜觸片分別疊裝在數(shù)層絕緣墊板內(nèi)組成雙斷點(diǎn)橋式結(jié)構(gòu)。而動(dòng)觸片又套裝在有手柄的絕緣方軸上，方軸隨手柄而旋轉(zhuǎn)。于是每層動(dòng)觸片隨方軸轉(zhuǎn)動(dòng)而變化位置來與靜觸片分?jǐn)嗪徒佑|。組合開關(guān)的頂蓋部分由凸輪、彈簧及手柄等零件構(gòu)成操作機(jī)構(gòu)，這個(gè)機(jī)構(gòu)由于采用了彈簧儲(chǔ)能，使開關(guān)快速閉合及分?jǐn)?。組
2、合開關(guān)的分合速度與手柄的旋轉(zhuǎn)速度無關(guān)，有利于滅弧。組合開關(guān)型號(hào)的含義如下圖所示觸刀極數(shù)每極觸刀額定電流（A）設(shè)計(jì)序號(hào)組合式刀開關(guān)組合開關(guān)型號(hào)的意義 H Z /- 3接觸器的用途是什么？選擇接觸器時(shí)主要考慮那些技術(shù)數(shù)據(jù)？答：接觸器用來頻繁地接通和切斷主電路或大容量控制電路，它廣泛地用于控制電動(dòng)機(jī)和其它電力負(fù)載。選擇接觸器主要考慮以下技術(shù)數(shù)據(jù)： 電源種類：交流或直流。 主觸點(diǎn)額定電壓、額定電流。 輔助觸點(diǎn)種類、數(shù)量及觸點(diǎn)額定電流。 勵(lì)磁線圈的電源種類、頻率和額定電壓。 額定操作頻率（次/h），即允許的每小時(shí)接通的最多次數(shù)。4比較接近式行程開關(guān)與機(jī)械式行程開關(guān)的優(yōu)缺點(diǎn)。答：接近式行程開關(guān)具有定位精度
3、高、操作頻率高、功率損耗小、壽命長(zhǎng)、耐沖擊振動(dòng)、耐潮濕、能適應(yīng)惡劣工作環(huán)境等優(yōu)點(diǎn)。5比較交、直流電磁鐵的特點(diǎn)。答：交流電磁鐵的特點(diǎn)：勵(lì)磁電流與銜鐵位置有關(guān)，當(dāng)銜鐵處于起動(dòng)位置時(shí)，電流最大；當(dāng)銜鐵吸合后，電流就降到額定值。吸力與銜鐵位置有關(guān)，但影響比直流電磁鐵小的多，隨著氣隙的減小，其吸力將逐漸增大，最后將達(dá)到1.52倍的初始吸力。直流電磁鐵的特點(diǎn)：勵(lì)磁電流的大小僅取決于勵(lì)磁線圈兩端的電壓及本身的電阻，而與銜鐵的位置無關(guān)。直流電磁鐵的吸力在銜鐵起動(dòng)時(shí)最小，而在吸合時(shí)最大，6一臺(tái)三相異步電動(dòng)機(jī)，額定功率為5.5KW，額定電壓為380V，額定電流為11.25A，起動(dòng)電流為額定電流的7倍，試選用對(duì)它進(jìn)
4、行控制和保護(hù)用的按鈕、接觸器、熱繼電器和組合開關(guān)。解：電動(dòng)機(jī)的額定電流，起動(dòng)電流為控制電路采用交流220V供電。則起動(dòng)按鈕（優(yōu)先選綠色）和停止按鈕（優(yōu)先選紅色）選用額定電壓220V的即可。接觸器選用交流接觸器，主觸點(diǎn)的額定電壓380V，額定電流應(yīng)78.75V，勵(lì)磁線圈選擇額定電壓交流220V，頻率50Hz。熱繼電器的額定電流應(yīng)1.05IN=1.0511.25=11.8A。組合開關(guān)的額定電壓為交流380V，三極觸點(diǎn)，額定電流78.25A即可。7在下表中填上電器的圖形符號(hào)和文字符號(hào)。名稱文字符號(hào)圖形符號(hào)線圈（元件）常開觸點(diǎn)常閉觸點(diǎn)刀開關(guān)Q接觸器KM時(shí)間繼電器延時(shí)閉合ST延時(shí)斷開延時(shí)閉合和延時(shí)斷開空
5、氣斷路器QF按鈕SB速度繼電器KS熱繼電器FR熔斷器FU行程開關(guān)ST8.自鎖環(huán)節(jié)怎樣組成？它起什么作用？并具有什么功能？答：一般可用起動(dòng)按鈕和接觸器的常開觸點(diǎn)并聯(lián)，然后再和接觸器的線圈串聯(lián)可得。當(dāng)按下起動(dòng)按鈕后，可實(shí)現(xiàn)長(zhǎng)動(dòng)，它又具有失壓保護(hù)功能。9什么是互鎖環(huán)節(jié)，它起到什么作用？答：將兩個(gè)接觸器的常閉觸點(diǎn)分別串聯(lián)到對(duì)方的線圈回路中，即可得到互鎖。它用來防止兩個(gè)接觸器同時(shí)得電。10 試設(shè)計(jì)一臺(tái)異步電動(dòng)機(jī)的控制線路。要求：（1）能實(shí)現(xiàn)起、停的兩地控制；（2）能實(shí)現(xiàn)點(diǎn)動(dòng)調(diào)整；（3）能實(shí)現(xiàn)單方向的行程保護(hù)；（4）要有短路和過載保護(hù)。SB5KMKSB1KSB3SB2KSB4STFRM3QKMFRu v
6、wFU1FU2圖1解：如圖1所示，左側(cè)為主電路，右側(cè)為控制電路。SB1 和SB2 是長(zhǎng)動(dòng)起動(dòng)按鈕，SB3 和SB4是停止按鈕，SB5是點(diǎn)動(dòng)按鈕，行程開關(guān)ST的常閉觸點(diǎn)起行程保護(hù)作用，熔斷器起短路保護(hù)作用，熱繼電器起過載保護(hù)作用。11今有兩臺(tái)電動(dòng)機(jī)，每次只允許一臺(tái)運(yùn)轉(zhuǎn)且一臺(tái)只需單方向運(yùn)轉(zhuǎn)，另一臺(tái)要求能正反轉(zhuǎn)。兩臺(tái)電動(dòng)機(jī)都要求有短路保護(hù)和過載保護(hù)，試畫出其電路。KM2M13M23KM3FR1FR2KM1Qu v wFU1FU2SB2KM3KM1KM3SB1KM2KM2SB4KM2KM1KM1KM2SB3KM3KM3KM1FR1FR2圖2解：如圖2所示。電動(dòng)機(jī)M2可單向運(yùn)行，KM3為其控制接觸器；電
7、動(dòng)機(jī)M3可正反轉(zhuǎn)運(yùn)行，KM1和KM2分別為正、反轉(zhuǎn)接觸器。If we dont do that it will go on and go on. We have to stop it; we need the courage to do it.His comments came hours after Fifa vice-president Jeffrey Webb - also in London for the FAs celebrations - said he wanted to meet Ivory Coast international Toure to discuss his c
8、omplaint.CSKA general director Roman Babaev says the matter has been exaggerated by the Ivorian and the British media.Blatter, 77, said: It has been decided by the Fifa congress that it is a nonsense for racism to be dealt with with fines. You can always find money from somebody to pay them.It is a
9、nonsense to have matches played without spectators because it is against the spirit of football and against the visiting team. It is all nonsense.We can do something better to fight racism and discrimination.This is one of the villains we have today in our game. But it is only with harsh sanctions t
10、hat racism and discrimination can be washed out of football.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.
11、I am going to be at the match 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
12、 2-1 win.Michel Platini, president 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.Baumg
13、artner the disappointing news: 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 ba
14、lloon, with capsule attached, 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
15、.17 kilometers) and into the 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
16、.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big ju
17、mpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins o
18、ut of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will ha
19、ve to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).cause there
電大《機(jī)電控制與可編程序控制器技術(shù)》形成性考核冊(cè)答案(一)
