電動(dòng)機(jī)控制外文文獻(xiàn)翻譯、中英文翻譯、外文翻譯

電動(dòng)機(jī)控制外文文獻(xiàn)翻譯、中英文翻譯、外文翻譯,電動(dòng)機(jī),控制,外文,文獻(xiàn),翻譯,中英文 附錄一：文獻(xiàn)翻譯 第 3 部分電動(dòng)機(jī)控制 3.3 繼電器和接觸器 3.3.1 控制繼電器 磁繼電器作為輔助設(shè)備控制開關(guān)控制電路和大型發(fā)動(dòng)機(jī)起動(dòng)器、接觸器線圈來控制小負(fù)載小型汽車、螺線管、電動(dòng)加熱器,燈光、音響信號(hào)裝置和其他繼電器。 磁繼電器是由一個(gè)電磁鐵,電磁鐵時(shí)打開或關(guān)閉電氣接觸器斷開。 繼電器一般用于放大機(jī)或放大接觸能力,或試驗(yàn)設(shè)備的開關(guān)函數(shù)添加更多電路。大多數(shù)繼電器用于控制電路;因此,他們的低評(píng)級(jí)(0-15 安培最大到 800 伏特)顯示的當(dāng)前水平降低它們的運(yùn)作方式。 磁繼電器不提供電機(jī)過載保護(hù)。通常這種類型的繼電器用于兩個(gè)線控制系統(tǒng)(任何電接觸式設(shè)備有兩個(gè)電線)。當(dāng)它被設(shè)計(jì)為使用瞬時(shí)接觸試驗(yàn)設(shè)備,如按鈕。任何可用的常開觸點(diǎn)可以連接作為一個(gè)持有三線制電路。 初學(xué)者來說,接觸器,繼電器是相似的在建設(shè)和運(yùn)營(yíng),但并不相同?？刂评^電器在各種單或雙擲安排常開的組合(不)和常閉(NC)接觸電路。雖然有一些 single-break 用于工業(yè)繼電器的接觸,大部分的繼電器用于機(jī)床制 15:40 接觸。這可能是特別感興趣的電工改變聯(lián)系人,常常閉,或反過來數(shù)控沒有。大多數(shù)機(jī)床繼電器有一些手段使這種變化。它的范圍從簡(jiǎn)單的翻聯(lián)系刪除搬遷彈簧位置變化。同時(shí),通過重疊接觸器在 這種情況下,一個(gè)接觸可以安排操作不同的時(shí)間相對(duì)于另一個(gè)在同一繼電器接觸。例 如,常開前聯(lián)系關(guān)閉(使)常閉觸點(diǎn)打開(休息)。繼電器在不同電壓等級(jí)、聯(lián)系人、聯(lián)系重排,物理尺寸,和附件提供輔助功能,如機(jī)械自鎖和時(shí)機(jī)。在使用繼電器為特定的應(yīng)用程序中,應(yīng)確定的第一個(gè)步驟控制(線圈)的電壓繼電器將必要的評(píng)級(jí)必須接觸,聯(lián)系人的數(shù)量以及其他特征。因?yàn)楦鞣N各樣的風(fēng)格的繼電器,可以選擇正確的傳遞幾乎任何應(yīng)用程序。繼電器通常用來打開和關(guān)閉操作控制電路比功率電路。 FIG.3-5 晶體管固態(tài) 開關(guān)裝置 典型應(yīng)用包括電動(dòng)機(jī)起動(dòng)器的控制和接觸器線圈的開關(guān)螺線管和其他繼電器的控制。繼電器是一個(gè)小而重要的開關(guān)的組成部分很多復(fù)雜的控制系統(tǒng)。低壓繼電器系統(tǒng)廣泛用于切換 住宅和商業(yè)照明電路和照明燈具。 而控制繼電器各制造商在外觀和結(jié)構(gòu)不同,他們是可以互換的控制布線系統(tǒng)產(chǎn)品規(guī)格是否匹配系統(tǒng)的需求。在許多形狀和配置控制繼電器是可用的。有防塵,控制繼電器的透明外殼。端子插入,就像一個(gè)電子管。另一個(gè)繼電器的類型是非常小的簧片繼電器,接觸封閉的玻璃。它操作一個(gè)磁場(chǎng)。 3.3.2 固態(tài)繼電器 相比一個(gè)電磁繼電器,固態(tài)繼電器沒有線圈或只需要最小值電壓和電流的打開和關(guān)閉它,固態(tài)繼電器依賴于電子設(shè)備,如晶體管和可控硅整流器(可控硅)切換。 3.3.3 晶體管作為開關(guān) 圖 3 - 5 顯示了一個(gè)基本的固態(tài)開關(guān)裝置用于邏輯組件(繼電器)。晶體管是 的核心元素。晶體管的基礎(chǔ)控制發(fā)射器和之間的電流收集器。在這種類型的晶體管,一個(gè)負(fù)面電壓允許發(fā)射極基極電流,固定在底座上流。這是由于材料的屬性發(fā)射極和基極的結(jié)。的 發(fā)射極基極電流使晶體管進(jìn)行從發(fā)射極電流收集器。一個(gè)正電壓固定在底座上防止發(fā)射極基極電流通過,晶體管停止開展。因此,它表現(xiàn)為一個(gè)封閉的接觸在第一個(gè)國(guó)家和作為一個(gè)開放聯(lián)系在第二。因?yàn)檫@個(gè)原因,行動(dòng)被稱為固態(tài)開關(guān),即沒有轉(zhuǎn)動(dòng)的聯(lián)系人需的。只有一個(gè)電子信號(hào)來打開或關(guān)閉電路。結(jié)果,固態(tài)設(shè)備非?？煽亢陀幸粋€(gè)非常漫長(zhǎng)的一生。固態(tài)設(shè)備不 滅弧,磨損,或惡化,磁繼電器 3.3.4 過載保護(hù) 當(dāng)固態(tài)設(shè)備使用磁開關(guān)、電壓瞬態(tài)抑制器有必要阻止一些有害的電子“噪音”。更加復(fù)雜的需要保護(hù)微機(jī)控制機(jī)器人組裝生產(chǎn)線。 3.3.5 接觸器 磁接觸器 eletromagnetically 操作開關(guān)提供一個(gè)安全、方便意味著連接和中斷分支電路。校長(zhǎng)之別接觸器和電動(dòng)機(jī)起動(dòng)器,接觸器不包含過載繼電器。接觸器結(jié)合試驗(yàn)控制裝置用于開關(guān)照明和取暖負(fù)荷和控制交流電機(jī)過載保護(hù)的情況下單獨(dú)提供。更大的接觸器尺寸用于提供遠(yuǎn)程控制相對(duì)大電流的電路太貴的權(quán)力運(yùn)行導(dǎo)致遠(yuǎn)程控制位置,FIG.3-6。這種靈活性是主要優(yōu)勢(shì)之一的電磁控制手動(dòng)控制。飛行員等設(shè)備按鈕, 浮子開關(guān)、壓力開關(guān)、限位開關(guān)、恒溫器提供接觸器的操作。 FIG.3-6 遠(yuǎn)程控制負(fù)載的一個(gè)優(yōu)勢(shì) 磁防 重型接觸 arc-chutes 提供大多數(shù)的更大的接觸器。的降落傘包含重銅線圈稱為防線圈,安裝以上聯(lián)系人在系列負(fù)載提供更好的消弧線。這些防磁線圈幫助撲滅電弧在接觸交流和直流負(fù)載下開放。電弧可能 是相似的強(qiáng)度隨著電弧焊接過程。一個(gè) arc-quenching 設(shè)備使用保證接觸壽命更長(zhǎng)。自熱電弧從接觸技巧非常迅速,聯(lián)系人保持冷靜,所以他們持續(xù)時(shí)間更長(zhǎng)。接觸和電動(dòng)機(jī)起動(dòng)器接觸,經(jīng)常打破沉重的水流受破壞性的燃燒 FIG.3-6 遠(yuǎn)程控制負(fù)載的一個(gè)優(yōu)勢(shì) 磁防 重型接觸 arc-chutes 提供大多數(shù)的更大的接觸器。包含重銅線圈稱為防線圈,安裝以上聯(lián)系人在系列 負(fù)載提供更好的消弧線。這些防磁線圈幫助撲滅電弧在接觸交流和直流負(fù)載下開放。電弧可能 是相似的強(qiáng)度隨著電弧焊接過程。一個(gè) arc-quenching 設(shè)備使用保證接觸壽命更長(zhǎng)。自熱電弧從接觸技巧非常迅速,聯(lián)系人保持冷靜,所以他們持續(xù)時(shí)間更長(zhǎng)。接觸和電動(dòng)機(jī)起動(dòng)器接觸,經(jīng)常打破沉重的水流受 破壞性的燃燒效果如果電弧不容易熄滅。時(shí)形成的弧接觸開放可以延長(zhǎng),撲滅由電動(dòng)機(jī)動(dòng)作如果在一個(gè)磁場(chǎng)。這個(gè)磁場(chǎng)是由磁防線圈提供。因?yàn)榇盆F的線圈通常與線串聯(lián),磁場(chǎng)強(qiáng)度和滅火行動(dòng)是弧的大小比例。 圖 3 - 7 是一個(gè)草圖防磁鐵的直導(dǎo)線(ab)位于與磁鐵場(chǎng)和串聯(lián)。這個(gè)數(shù)字可以表示直流極性或瞬時(shí) 交流,交流電流、防線圈磁場(chǎng)和導(dǎo)體(電弧)磁場(chǎng)同時(shí)反向。根據(jù)弗萊明的左手定則, 電機(jī)動(dòng)作會(huì)力量 售票員在一個(gè)向上的方向。應(yīng)用右手定則的信號(hào)指揮表明,導(dǎo)線周圍的磁場(chǎng)艾滋病的主要領(lǐng)域和底部 反對(duì)在頂部,售票員因此產(chǎn)生一個(gè)向上的力量。 圖 3 - 8 顯示了年代的圖 3 - 7 節(jié)線(ab)取而代之的是一組聯(lián)系人。聯(lián)系人已經(jīng)開 始開放,他們之間有一個(gè)弧。圖 3 - 9 顯示了什么是因?yàn)榇判缘男袆?dòng)。部分顯示了開始時(shí)的撓度弧由于影響電動(dòng)機(jī)的行動(dòng)。B 部分表明,接觸更多的然后和弧開始爬上角,因 為汽車行動(dòng)的影響增加溫度。圖 3 - 9 所示的 C 部分的角附近的弧。在這點(diǎn),電弧加長(zhǎng), 將熄滅。 防磁的作用是將電弧向上在同一時(shí)間接觸弧。因此,電弧延長(zhǎng)速度超過通常會(huì)發(fā) 生 因?yàn)閱为?dú)的接觸。很明顯,時(shí)間越短弧允許存在,傷害就越少聯(lián)系。大多數(shù)弧淬火動(dòng)作 在這一原則。 3.3.6 機(jī)械交流接觸器和繼電器 舉行的機(jī)械繼電器或接觸器,是由電磁鐵但電磁鐵在繼電器自動(dòng)斷開了聯(lián)系。因此,這些繼電器機(jī)械在位置和沒有電流流過開關(guān)后操作這些電磁鐵的線圈。很明顯,因此,在連續(xù)操作多個(gè)單位的實(shí)質(zhì)性的大小會(huì)降低電能的需求。同時(shí),磁保持繼電器,相比之下,將改變接觸位置的電壓損失電磁鐵,而機(jī)械繼電器只會(huì)回應(yīng)的行動(dòng) 控制裝置。操作順序 指的是圖 3 - 10,暫時(shí)按下“關(guān)”按鈕時(shí),當(dāng)前的流動(dòng)從 L1 到“on”按鈕接觸通電線圈通過現(xiàn)在的關(guān)閉 清除接觸,L2?，F(xiàn)在的繼電器關(guān)閉和鎖存器機(jī)械。在同一時(shí)間關(guān)閉聯(lián)系人(在圖 3-11),照明燈具的銀行當(dāng)斷路器關(guān)閉。 門閂,繼電器,從而關(guān)閉燈,暫時(shí)關(guān)閉按鈕被按下, 門閂,繼電器和打開聯(lián)系人,關(guān)掉燈。大多數(shù)操作線圈 不為連續(xù)運(yùn)行而設(shè)計(jì)的。因此,他們自動(dòng)斷開聯(lián)系 防止意外線圈倦怠。這些線圈清算聯(lián)系人交替變化的位置接觸器閉鎖位置的變化。 圖 3 - 12 顯示了一個(gè)三相電力負(fù)荷的應(yīng)用程序使用一個(gè)主接觸器斷開配電盤。選擇性單、三相分支電路可以切換由其他獨(dú)立機(jī)械接觸器或繼電器舉行。這些機(jī)械接觸器和繼電器機(jī)電設(shè)備,圖 3。他們提供了一個(gè)安全、方便的切換電路,安靜的操作,能量電路連接效率和連續(xù)性的要求安裝。例如,電路連續(xù)性在電源故障自動(dòng)處理設(shè)備通常是重要的,在一系列的操作必須繼續(xù)從權(quán)力后中斷嗎恢復(fù),而然后返回序列的開始。接觸器和安靜的操作繼電器是必需的在許多控制系統(tǒng)用于醫(yī)院、學(xué)校、辦公樓。機(jī)械接觸器和繼電器通常用于地方輕微的嗡嗡聲,交流磁設(shè)備的特點(diǎn),是令人反感的。此外, 機(jī)械繼電器機(jī)床控制電路中經(jīng)常使用。這些繼電器可以鎖住和拉開通過限位開關(guān)的操作, 時(shí)間繼電器,起動(dòng)器聯(lián)鎖、timeclocks 光電電池,其他控制繼電器、按鈕。一般來說, 機(jī)械繼電器可在 10 - 15-ampere 大小;機(jī)械接觸器也可以在尺寸范圍從 30 安培 1200 安培。 3.4.2 流體減震器時(shí)間繼電器 磁,油緩沖器延時(shí)繼電器可能用于電壓 800 伏交流電直流。聯(lián)系人是由鐵芯的運(yùn)動(dòng)。的磁場(chǎng) 電磁線圈拳的鐵芯對(duì)制動(dòng)力活塞移動(dòng)充油的減震器。這種類型的繼電器不是很準(zhǔn)確。活塞必須允許定居下來之間的緩沖器的底部連續(xù)時(shí)間周期。如果活塞不允許全部返回,時(shí)間是不穩(wěn)定的。減震器的延時(shí)繼電器延時(shí)后磁鐵是精力充沛。接觸不同可能常開或常閉應(yīng)用程序。與磁過載繼電器、減震器延時(shí)繼電器運(yùn)行電壓線圈連接整個(gè)線通過接觸或開關(guān)。過載繼電器操作的電流線圈所受影響電動(dòng)機(jī)電流負(fù)載。流體減震器 時(shí)間繼電器用于許多應(yīng)用程序: ■ 控制加速電機(jī)接觸器開始 ■ 時(shí)間關(guān)閉或打開閥門的制冷設(shè)備 ■ 為任何應(yīng)用程序的操作序列延遲。 有必要的時(shí)間延遲是非常準(zhǔn)確的。這些繼電器使用硅膠減震器流體不是一個(gè)石油。流體有助于消除 不同粘度的影響時(shí)間由于環(huán)境溫度的變化。硅膠流體運(yùn)作成功的環(huán)境溫度范圍+ 48.9℃到-34.4℃。的 可以輕松調(diào)整時(shí)間范圍從 2 秒到 30 秒。多次接觸緩沖器時(shí)間繼電器用于直流電機(jī)起動(dòng)。當(dāng)線圈這種類型的延時(shí)繼電器精力充沛,紛紛聯(lián)系密切,中間有一個(gè)時(shí)間差每一個(gè)結(jié)束。 3.4.3 氣動(dòng)計(jì)時(shí)器 的結(jié)構(gòu)和性能特點(diǎn)氣動(dòng)(空氣)定時(shí)器使它適合多數(shù)工業(yè)應(yīng)用。氣動(dòng)計(jì)時(shí)器有以下特點(diǎn): ■ 不受正常環(huán)境溫度和大氣壓力的變化 ■ 可調(diào)在一個(gè)廣泛的時(shí)間周期 ■ 良好的重復(fù)精度 ■ 可用各種各樣的聯(lián)系和時(shí)間安排。 這種類型的繼電器有一個(gè)氣動(dòng)延時(shí)單元,由一個(gè)機(jī)械操作磁鐵的結(jié)構(gòu)。延時(shí)功能取決于空氣通過一個(gè)限制的轉(zhuǎn)移孔板鋼筋的使用合成橡膠波紋管或隔膜。時(shí)間范圍是調(diào)整定位針閥不同數(shù)量的孔或排氣限制。激勵(lì)的過程或斷電路可以控制的氣動(dòng)時(shí)間繼電器試驗(yàn)設(shè)備(如按鈕、限位開關(guān)或恒溫繼電器。自從權(quán)力了由時(shí)間繼電器線圈是小, 敏感的控制設(shè)備可用于控制操作序列。氣動(dòng)時(shí)間繼電器用于汽車加速和自動(dòng)控制電路。自動(dòng)控制是必要的在應(yīng)用程序重復(fù)精度是必需的,例如控制序列操作的機(jī)床和控制,工業(yè)過程操作,輸送線。 3.4.4 磁限時(shí)繼電器 如果線圈中的電流增加,那么由于自感電動(dòng)勢(shì)方向反對(duì)行為增加線圈的電流。如果線圈中的電流減少,emf 由于自感線圈的行為方向反對(duì)降低線圈的電流。一種磁期 限繼電器有一個(gè)線圈繞在一個(gè)空心銅柱含鐵核心。其他時(shí)間限制繼電器線圈銅夾套。對(duì)任何一種繼電器、時(shí)間延遲繼電器下降時(shí)提供。線圈的電路斷開時(shí),電流迅速下降到零。因此,作為線圈的磁通量減少,削減短路銅缸和在汽缸產(chǎn)生一個(gè)電壓。這種感應(yīng)電壓發(fā)送電流通過銅汽缸。由于當(dāng)前,通量是磁鐵電樞的產(chǎn)生一段時(shí)間后,線圈電路壞了。延遲時(shí)間是有限的在電路中線圈和鐵。Figure3-15 素描的磁時(shí)間限制繼電器。繼電器是精力充沛時(shí),電樞(M)畫的核心(N)。同時(shí),在嗎彈簧的張力會(huì)畫出電樞遠(yuǎn)離核心。維護(hù)的通量當(dāng)前在銅套死,時(shí)間電樞釋放所依賴一些嗎春天的緊張程度。釋放 時(shí)間也可以通過插入不同的銅墊片在 M 和 N 之間的差距,更厚的墊片,通量越低, 越早電樞釋放。磁期限繼電器用于短路電阻啟動(dòng)的步驟馬達(dá)。這種類型的繼電器銜鐵, 皮卡是瞬時(shí)的。輟學(xué)的時(shí)間延遲通過使用非磁性電樞調(diào)整墊片和彈簧。 3.4.5 電容器限時(shí)繼電器 假設(shè)為電容器充電連接直流線,然后它暫時(shí)電容器直流通過繼電器線圈放電。當(dāng)前感應(yīng)線圈會(huì)慢慢衰減, 根據(jù)電容的相對(duì)價(jià)值,電感和電阻的放電電路。如果一個(gè)繼電器線圈和電容器并聯(lián)直流線路,電容器充電 線電壓的值和當(dāng)前出現(xiàn)在線圈。如果線圈和電容器組合是現(xiàn)在從這條線,當(dāng)前的線圈將開始減少曲線如圖 3-16 所示。 如果調(diào)整繼電器,使銜鐵釋放在當(dāng)前 i1,t1 的時(shí)間延遲獲得的。時(shí)間延遲可以增加到一個(gè)值的t2 通過調(diào)整繼電器,以便電樞不會(huì)被釋放,直到i2 的電流降低到一個(gè)值。電位器用作一個(gè)可調(diào)電阻來改變時(shí)間。這 阻容(RC)理論是用于工業(yè)電子和固態(tài)控制也。這個(gè)計(jì)時(shí)器是高度精確和用于汽車加速度控制,在許多工業(yè)過程中。 3.4.6 電子計(jì)時(shí)器 電子計(jì)時(shí)器使用固態(tài)組件來提供所需的時(shí)間延遲。圖 3 - 17 所示圖這個(gè)計(jì)時(shí)器。計(jì)時(shí)器有一個(gè)發(fā)光二極管(LED)當(dāng)時(shí)間繼電器斷開,而時(shí)機(jī)一一閃過,而精力充沛。的單位符合標(biāo)準(zhǔn)的工業(yè)控制繼電器安裝。 3.4.7 選擇延時(shí)繼電器 在選擇一個(gè)特定的時(shí)間繼電器 應(yīng)用程序,應(yīng)該是以下因素 仔細(xì)考慮。 ■ 長(zhǎng)度所需的時(shí)間延遲 ■ 時(shí)間范圍要求 ■ 容許誤差 ■ 周期或操作和重置時(shí)間 ■ 成本 ■ 額外的需求 長(zhǎng)度所需的時(shí)間延遲所需的時(shí)間延遲是由機(jī)器或過程的類型計(jì)時(shí)器將控制。時(shí)間延遲將范圍從一小部分第二個(gè)幾分鐘。所需的時(shí)間范圍這句話時(shí)間范圍意味著的各種時(shí)間間隔計(jì)時(shí)器調(diào)整。計(jì)時(shí)器是可用的,可以設(shè)置為 1 秒的時(shí)間延遲,100 秒,之間的延遲或任何值 1 和 100 秒。在選擇使用一臺(tái)機(jī)器或一個(gè)計(jì)時(shí)器過程中,應(yīng)該足夠?qū)挿秶赡苄枰幚淼母鞣N延時(shí)時(shí)間機(jī)器或過程。具體時(shí)間值必須找到時(shí)間范圍內(nèi)任何位置的審判和錯(cuò)誤。規(guī)模提供了一個(gè)計(jì)時(shí)器主要目的是允許快速重置計(jì)時(shí)器到時(shí)間位置之前確定是正確的對(duì)于一個(gè)給定的操作。 容許誤差，計(jì)時(shí)器都受到一些錯(cuò)誤,也就是說,可能會(huì)有正負(fù)時(shí)間變化連續(xù)時(shí)間操作之間相同的設(shè)置。誤差隨的數(shù)量類型的定時(shí)器和操作條件。這個(gè)錯(cuò)誤通常的百分比表示時(shí)間設(shè)定。任何計(jì)時(shí)器的誤差百分比取決于類型的計(jì)時(shí)器,環(huán)境溫度尤其是低溫), 線圈溫度、線電壓和之間的時(shí)間長(zhǎng)度操作。 所需的操作周期和重置時(shí)間為一種計(jì)時(shí)器,計(jì)時(shí)器成為手術(shù)當(dāng)電路打開或關(guān)閉。時(shí)間延遲,那么發(fā)生在應(yīng)用程序進(jìn)程開始之前。一旦特定過程操作完成時(shí),計(jì)時(shí)器電路重置本身。必須精力充沛或電路每次時(shí)機(jī)行動(dòng)需要斷開。第二種類型的計(jì)時(shí)器被稱為一個(gè)過程計(jì)時(shí)器。當(dāng)連接到一個(gè)電路,提供了一系列事件,控制在另一個(gè)地方。不斷循環(huán)重復(fù),直到電路斷開。 一個(gè)計(jì)時(shí)器的選擇時(shí)要考慮的一個(gè)重要因素是速度定時(shí)器重置。重置時(shí)間繼電器機(jī)制所需的時(shí)間回到原來的位置。一些工業(yè)過程要求瞬間繼電器復(fù)位。其他進(jìn)程需要一個(gè)緩慢重置時(shí)間。重置時(shí)間隨延時(shí)繼電器的類型和時(shí)間延遲的長(zhǎng)度。 成本 當(dāng)有幾種電磁計(jì)時(shí)器,滿足給定的需求應(yīng)用程序。建議選擇計(jì)時(shí)器與最小數(shù)量的操作部分。在 句話說,選擇最簡(jiǎn)單的定時(shí)器。在大多數(shù)情況下,這個(gè)計(jì)時(shí)器可能是最低的成本。 3.5 二線控制 雙線式控制可能是撥動(dòng)開關(guān),壓力開關(guān),浮子開關(guān),限位開關(guān),溫控器,或任何其他類型的開關(guān)有明確的立場(chǎng)。表示,設(shè)備類型通常被設(shè)計(jì)成處理小電流。雙線式控制裝置不會(huì)攜帶足夠的電流操作大型汽車。此外,230 伏電機(jī)和三相電機(jī)通常需要不止一個(gè)聯(lián)系人聯(lián)系提供二線設(shè)備。雙線式控制可以連接到操作線圈的磁開關(guān),如圖3-18 所示。開關(guān)關(guān)閉時(shí),通過線圈控制電路完成 M),當(dāng)線圈激勵(lì)它關(guān)閉聯(lián)系人在 M 和電機(jī)運(yùn)行。 3.6.1 三線控制 三線控制電路采用瞬時(shí)接觸,起停站和電路聯(lián)鎖連接在開始按鈕的同時(shí),保持電路。一般來說,三線設(shè)備連接,如圖 3-19 所示。雖然安排的各個(gè)部分可能會(huì)有所不同從一個(gè)制造商的切換到另一個(gè),基本電路是相同的。這個(gè)電路的操作順序是:當(dāng)開始按鈕被推,通過線圈電路完成(顯示為 M)和聯(lián)系人在 M 關(guān)閉。的權(quán)力電路接觸電動(dòng)機(jī)也密切(沒有顯示)。開始按鈕被釋放時(shí),保持聯(lián)系在保持這個(gè)輔助觸點(diǎn)。當(dāng)起動(dòng)器中使用這種方式,它據(jù)說是“維護(hù)”或“封口”。保持聯(lián)系關(guān)閉,電路仍然是通過線圈完成。如果停止按鈕被推,線圈的電路壞了,失去了能源和聯(lián)系人在開放。停止按鈕被釋放時(shí),電路仍然開放因?yàn)楸３致?lián)系和開始按鈕必須再次被推到完成電路。過載保護(hù)的操作打開控 制電路,導(dǎo)致相同的的效果。如果電源電壓失敗,電路斷開。當(dāng)電源電壓恢復(fù),電路仍然開放,直到重新開始按鈕推。這樣的安排被稱為無電壓保護(hù)和保護(hù)運(yùn)營(yíng)商和設(shè)備。按鈕站接線圖圖 3-19(B)代表物理站。它顯示單元的相對(duì)位置,內(nèi)部線路,連接起動(dòng)器。電線終端貼上 1、2 和 3(引起名稱“三線控制”)。常閉輔助觸點(diǎn)用于開關(guān)指示燈。電動(dòng)機(jī)沒有運(yùn)行,這些聯(lián)系是開放的,當(dāng)電機(jī)停止,關(guān)閉,指示燈。一個(gè)指示燈可以安裝時(shí)顯示電機(jī)運(yùn)行。對(duì)于這個(gè)情況下,指示燈控制終端 3 和 2 號(hào)線之間的連接。除了這個(gè)修改電路是一個(gè)基本的三線,按鍵控制電路。 3.6.2 順序來推動(dòng)測(cè)試指示燈 有必要重新啟動(dòng)電機(jī)后,停止了三線控制電路低電壓保護(hù)。一個(gè)指示燈通常是當(dāng)電動(dòng)機(jī)停止,這樣它的信號(hào)可以導(dǎo)致罷工的問題是清除后重新啟動(dòng)。因?yàn)轱w行員燈是一個(gè)重要組成部分在這種情況下,他們經(jīng)常以確保操作進(jìn)行測(cè)試。來推動(dòng)測(cè)試飛行員燈光炫耀立即如果電路或者如果燈燒壞了。圖 3 的一部分顯示了這種電路的線路。三線電動(dòng)機(jī)起動(dòng)器控制電路像往常一樣連接。注意,信號(hào)燈是能量從三號(hào)航站樓到 C,通過常閉按鈕 L2。測(cè)試,燈被打開在 C 和電路在 L1 關(guān)閉它。按鈕的安排,測(cè)試燈直接跨線 1 和 2 3.6.3 報(bào)警沉默電路 警報(bào)喇叭,大聲蜂群還用于生產(chǎn)系統(tǒng)調(diào)用故障。問題是承認(rèn)企圖壓制這種“噪音污染”。一個(gè)典型電路如圖 3 - 21 所示。假設(shè)一個(gè)工業(yè)系統(tǒng)的高壓危險(xiǎn)的繼續(xù)。這樣的條件將關(guān)閉一個(gè)壓力開關(guān)。這個(gè)開關(guān)關(guān)閉時(shí),鬧鐘響起通過常閉觸點(diǎn) s .此外,紅色的指示燈光。提醒時(shí),維修人員可以通過壓低沉默鬧鐘“關(guān)閉”按鈕。紅燈繼續(xù)默默地宣布 這個(gè)問題,直到它被清除。后壓力開關(guān)打開時(shí),報(bào)警系統(tǒng)可以重新激活通過按按鈕。有幾乎是無限的控制電路采用三線制。 3.6.4 單獨(dú)控制 它有時(shí)需要操作按鈕或其他控制設(shè)備在一些低電壓電動(dòng)機(jī)的電壓。控制系統(tǒng)的這種情況下,一個(gè)單獨(dú)的來獲得的隔離變壓器或一個(gè)獨(dú)立的電壓供應(yīng)─提供控制的權(quán)力電路。這個(gè)獨(dú)立的電壓是電動(dòng)機(jī)的主電源分開。一種單獨(dú)的控制圖 3-22 所示。這是一個(gè)冷卻的原理圖電路對(duì)商業(yè)空調(diào)安裝。恒溫器要求冷卻時(shí),壓縮機(jī)電動(dòng)機(jī)起動(dòng)器線圈(顯示為 M)是通過降壓隔離精力充沛變壓器。當(dāng)線圈 M 是亢奮時(shí),在 240 伏電源接觸開關(guān)啟動(dòng)制冷壓縮機(jī)電機(jī)。由于控制電路是電源電路的分開隔離控制變壓器,沒有兩個(gè)電路之間的電氣連接。對(duì)于這個(gè)原因,起動(dòng)器上的跳線連接到 L2 為不同電壓應(yīng)該刪除。然而,過載繼電器控制必須包括在單獨(dú)的控制線路接觸。維護(hù)技術(shù)人員還必須確?？刂谱儔浩麟妷浩ヅ潆妷?使用適當(dāng)?shù)倪B接。 附錄二：英文原文 PART 3 ELECTRIC MOTOR CONTROL 3.3 RELAYS AND CONTACTORS 3.3.1 Control Relays Control magnetic relays are used as auxiliary devices to switch control circuits and large motor starter and contactor coils, and to control small loads such as small motors, solenoids, electric heaters, pilot lights, audible signal devices and other relays. A magnetically held relay is operated by an electromagnet which opens or closes electrical contactors when the electromagnet is deenergized. FIG.3-3 Elementary diagram using (A) FIG.3-4 Heavy duty, double selector A single-break, three-position selector switch for (A)Two position switch and (B) Two-position, single- and (B) Three position switches break switch Relays are generally used to enlarger or amplify the contact capability, or multiply the switching function of a pilot device by adding more contacts to circuit. Most relays are used in control circuits; therefore, their lower ratings (0-15 amperes maximum to 800 volts) show the reduced current levels at which they operate. Magnetic relays do not provide motor overload protection. This type of relay ordinarily is used in a two wire control system (any electrical contact-making device with two wires). Whenever it is designed to use momentary contact pilot devices, such as push buttons. Any available normally open contact can be wired as a holding circuit in a three-wire system. Starters, contactors, and relays are similar in construction and operation but are not identical. Control relays are available in single- or double-throw arrangements with various combinations of normally open (NO) and normally closed (NC) contact circuits. While there are some single-break contacts used in industrial relays, most of the relays used in machine tool control have double-break contacts. It may be of particular interest to an electrician to know about changing contacts that are normally open to normally closed, or the other way around NC to NO. Most machine tool relays have some means to make this change. It ranges from simple flip-over contact to removing the contacts and relocating with spring location changes. Also, by overlapping contactors in this case, one contact can be arranged to operate at a ifferent time relative to another contact on the same relay. For example, the normally open contact closes (makes) before the normally closed contact opens (breaks). Relays differ in voltage ratings, number of contacts, contact rearrangement, physical size and in attachments to provide accessory functions such as mechanical latching and timing. In using a relay for a particular application, one of the first steps should be determine the control (coil)voltage at which the relay will operate The necessary contact rating must be made, as well as the number of contacts and other characteristics needed. Because of the variety of styles of relays available, it is possible to select the correct relay for almost any application. Relays are used more often to open and close control circuits than to operate power circuits. Typical applications include the control of motor starter and contactor coils, the switching of solenoids, and the control of other relays. A relay is a small but vital switching component of many complex control systems. Low-voltage relay systems are used extensively in switching residential and commercial lighting circuits and individual lighting fixtures. While control relays from various manufacturers differ in appearance and construction, they are interchangeable in control wiring system if their specifications are matched to the requirements of the system. Control relays are available in many shapes and configurations. There is dustproof, transparent enclosure of a control relay. The terminals plug in, like an electron tube. Another type of relay is the very small reed relay, with the contacts enclosed in glass. It is operated with a magnetic field. 3.3.2 Solid-state Relay In comparison to an electromagnetic relay, the solid-state relay has no coil or contacts and requires only minimum values of voltage and current to turn it on and off. The solid-state relay depends on electronic devices, such as transistors and silicon controlled rectifiers (SCR) for switching. 3.3.3 The Transistor as A Switch Figure 3-5 shows a basic solid-state switching deviceused in a logic component (relay). The transistor isthe heart of the element. The base of the transistorcontrols the current flow between the emitter and thecollector. In this type of the transistor, a negativevoltage on the base allows emitter- base current to flow. This is due to the properties of the material at the junction of the emitter and the base. The emitter-base current causes the transistor to conduct a current flow from the emitter to the collector. A positive voltage on the base prevents emitter-base current from flowing, and the transistor stops conducting. Therefore, it behaves as a closed contact in the first state and as an open contact in the second For this reason, the action is called solid-state switching, that is, no moving contacts are required. There is only an electrical signal to open or close the circuit. As a result, the solid-state device is very reliable and has an exceptionally long life. Solid-state devices are not subject to arcing, wear, or deterioration, as are magnetic relays. 3.3.4 Surge Protection When solid-state devices are used with magnetic switches, a voltage transient suppressor may be necessary to prevent some of the more harmful electrical “noise”. Much more sophisticated protection is required for microcomputers that control robots on assembly production lines. 3.3.5 Contactors Magnetic contactors are eletromagnetically operated switches that provide a safe and convenient means for connecting and interrupting branch circuits. The principal diference between a contactor and a motor starter is that the contactor does not contain overload relays. Contactors are used in combination with pilot control devices to switch lighting and heating loads and to control ac motors in those cases where overload protection is provided separately. The larger contactor sizes are used to provide remote control of relatively high-current circuits where it is too expensive to run the power leads to the remote controlling location, FIG.3-6.This flexibility is one of main advantages of electromagnetic control over manual control. Pilot devices such as push buttons, float switches, pressure switches, limit switches, and thermostats are provided to operate the contactors. FIG.3-6 An advantage of a remote control load Magnetic Blowout Heavy-duty contact arc-chutes are provided on most of larger contactors. The chutes contain heavy copper coils called blowout coils, mounted above the contacts in series with the load to provide better arc suppression. These magnetic blowout coils help to extinguish an electric arc at contacts opening under alternating current and direct-current loads. The arc may be similar in intensity as the electric arc welding process. Anarc-quenching device is used to assure longer contact life. Since the hot arc is transferred from the contact tips very rapidly, the contacts remain cool and so they last longer. Contact and motor starter contacts that frequently break heavy currents are subject to a destructive burning effect if the arc is not quickly extinguished. The arc that is formed when the contacts open can be lengthened, and extinguished by motor action if it is in a magnetic field. This magnetic field is provided by the magnetic blowout coil. Since the coil of the magnet is usually in series with the line, the field strength and extinguishing action are in proportion to the size of the arc. Figure 3-7 is a sketch of a blowout magnet with a straight conductor (ab) located in the field and in series with the magnet. This Figure can represent either dc polarity or instantaneous ac. With ac current, the blowout coil magnetic field and conductor (arc) magnetic field will reverse simultaneously. According to Fleming’s left-hand rule, motor action will tend to force the conductor in an upward direction. The application of the right-hand rule for signal conductor shows that the magnetic field around the conductor aids the main field on the bottom and opposes it on the top, thus producing an upward force on the conductor. Figure 3-8 shows s section of Figure 3-7 with the wire (ab) replaced by a set of contacts. The contacts have started to open and there is an arc between them. Figure 3-9 shows what happens because of the magnetic action. Part A shows the beginning deflection of the arc because of the effect the motor action. Part B shows that the contacts are separated more then in A and the arc is beginning to climb up the horns because of the motor action and the effect of increased temperature. Part C of Figure 3-9 shows the arc near the tips of the horns. At this point, the arc is so lengthened that it will be extinguished. FIG.3-7 Illustration of the magnetic blowout FIG.3-8 Section of blowout magnet with principle. Straight conductor simulates arc. straight conductor replaced by a set conducting between contacts. An arc is the contacts. The function of the blowout magnet is to move the arc upward at the same time that the contacts arc opening. As a result, the arc is lengthened at a faster rate than will normally occur because of the opening of the contacts alone. It is evident that the shorter the time the arc is allowed to exist, the less damage it will do to the contacts. Most arc quenching action is based upon this principle. 3.3.6 AC Mechanically Held Contactors and Relays A mechanically held relay, or contactor, is operated by electromagnets but the electromagnets are automatically disconnected by contacts within the relay. Accordingly, these relays are mechanically held in position and no current flows through the operating coils of these electromagnets after switching. It is apparent, therefore, that near continuous operation of multiple units of substantial size will lower the electrical energy requirements. Also, the magnetically held relay, in comparison, will change contact position upon loss of voltage to the electromagnet, whereas the mechanically held relay will respond only to the action of the control device. Sequence of Operation Referring to Figure 3-10, when the“off”push button is pressed momentarily, current flows from L1 through the “on” push button contact energizing the M coil through the now closed clearing contact, to L2. The relay now closes and latches mechanically. At the same time it closes M contacts (in Figure 3-11), lighting a bank of lamps when the circuit breaker is closed. To unlatch the relay, thereby turning the lamps off, the off button is pressed momentarily, unlatching the relay and opening the contacts M, turning off the lamps. Most operating coils are not designed for continuous duty. Therefore, they are disconnected automatically by contacts to prevent an accidental coil burnout. These coil clearing contacts change position alternately with a change in contactor latching position. FIG.3-9 Arc deflection between contacts FIG.3-10 Mechanically held relay control circuit Figure 3-12 shows a three-phase power load application using one main contactor to disconnect distribution panel. Selective single, or three-phase, branch circuits may be switched independently by other mechanically held contactors or relays. These mechanically held contactors and relays are electromechanical devices, Figure 3-13. They provide a safe and convenient means of switching circuits where quiet operation, energy efficiency, and continuity of circuit connection are requirements of the installation. For example,circuit continuity during power failures is often important in automatic processing equ