軟起動(dong)是一種集防爆(bao)電(dian)機(ji)軟起動(dong)、軟停(ting)車(che)、輕(qing)載節能(neng)和多種保護功能(neng)于一體的(de)新穎電(dian)機(ji)控制裝置。國際簡稱：Soft Starter。
防(fang)爆電(dian)(dian)(dian)機傳統的起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)方(fang)式有全(quan)(quan)壓(ya)(ya)起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)和(he)將壓(ya)(ya)起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)，軟起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)是一種完全(quan)(quan)區別于全(quan)(quan)壓(ya)(ya)和(he)降壓(ya)(ya)起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)的新的起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)方(fang)式，是電(dian)(dian)(dian)子過程控(kong)制技(ji)術。所(suo)謂軟起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)，是以斜坡控(kong)制方(fang)式起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)，使電(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機轉速平滑，逐步提高到(dao)額定轉速。按(an)照電(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)電(dian)(dian)(dian)流(liu)大(da)小進行分類，全(quan)(quan)壓(ya)(ya)和(he)降壓(ya)(ya)起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)屬(shu)(shu)于大(da)電(dian)(dian)(dian)流(liu)起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)方(fang)式，軟起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)屬(shu)(shu)于小電(dian)(dian)(dian)流(liu)起(qi)(qi)(qi)動(dong)(dong)(dong)(dong)方(fang)式。
防(fang)爆電機全壓起動，起動電流(liu)是(shi)(shi)額(e)定電流(liu)的4-7倍，起動沖(chong)擊電流(liu)是(shi)(shi)起動電流(liu)的1.5-1.7倍；起動電流(liu)大(da)，起動轉矩(ju)不相(xiang)應增大(da)，Ｔs=ＫtＴn＝Ｋ(0.9-1.3)Ｔn。
防爆電(dian)機降壓起(qi)(qi)動(dong)(dong)(dong)，可部(bu)分減小起(qi)(qi)動(dong)(dong)(dong)電(dian)流，起(qi)(qi)動(dong)(dong)(dong)轉(zhuan)矩下降到額定(ding)電(dian)壓的Ｋ2倍。降壓起(qi)(qi)動(dong)(dong)(dong)是輕載起(qi)(qi)動(dong)(dong)(dong)，有起(qi)(qi)動(dong)(dong)(dong)沖擊(ji)(ji)電(dian)流、起(qi)(qi)動(dong)(dong)(dong)電(dian)流及二次沖擊(ji)(ji)電(dian)流；二次沖擊(ji)(ji)電(dian)流同樣對(dui)配(pei)電(dian)系(xi)統(tong)有麻煩。
全壓和降壓起動的大電流，致使電動機諧波(bo)磁(ci)勢(shi)增大，增大后(hou)的諧波(bo)磁(ci)勢(shi)又加(jia)(jia)劇(ju)了(le)附加(jia)(jia)轉矩(ju)(ju)，附加(jia)(jia)轉矩(ju)(ju)是(shi)電機起動時產生震動和噪音的原因。
全(quan)壓和降壓起(qi)(qi)動(dong)(dong)，都要受單位時(shi)(shi)間內起(qi)(qi)動(dong)(dong)次(ci)數的(de)限制。電(dian)動(dong)(dong)機(ji)本身(shen)的(de)發熱主要建立在短時(shi)(shi)間大(da)電(dian)流(liu)時(shi)(shi)。如通過6倍額(e)定(ding)電(dian)流(liu)，溫升(sheng)為8-15℃/S；起(qi)(qi)動(dong)(dong)裝置的(de)自耦變壓器或交(jiao)(jiao)流(liu)接(jie)觸器起(qi)(qi)動(dong)(dong)引起(qi)(qi)堆積熱；如交(jiao)(jiao)流(liu)接(jie)觸器一般要求起(qi)(qi)動(dong)(dong)次(ci)數每分(fen)鐘不超過10次(ci)。而軟(ruan)起(qi)(qi)動(dong)(dong)器可(ke)頻繁操作(zuo)，具(ju)有①電(dian)動(dong)(dong)機(ji)起(qi)(qi)動(dong)(dong)電(dian)流(liu)小，溫升(sheng)低；②軟(ruan)起(qi)(qi)動(dong)(dong)器采用的(de)無觸點電(dian)子元件(jian)，除(chu)大(da)功率可(ke)控硅外，工作(zuo)時(shi)(shi)溫升(sheng)很(hen)低。
此外，防爆電機軟起(qi)(qi)(qi)動器還具有(you)多種保護功能，配合硬(ying)件電路，軟件設計有(you)過載(zai)、斷(duan)相、欠壓、過壓等保護程序，動作可(ke)靠程度高。總結來(lai)看，軟起(qi)(qi)(qi)動器很好的(de)解(jie)決了全壓和降(jiang)壓起(qi)(qi)(qi)動電流(liu)過大及其(qi)派生的(de)許多問題(ti)。