西門子SIEMENS變頻器

運(yun)行(xing)多年的(de)(de)西(xi)門(men)子(zi)(zi)電(dian)(dian)機(ji)(ji)，因(yin)西(xi)門(men)子(zi)(zi)電(dian)(dian)機(ji)(ji)的(de)(de)運(yun)行(xing)溫升和(he)受潮等原因(yin)，繞(rao)組(zu)(zu)的(de)(de)絕(jue)(jue)緣(yuan)程(cheng)度(du)已大大降低，甚至有了明顯的(de)(de)絕(jue)(jue)緣(yuan)缺陷，處于電(dian)(dian)壓(ya)擊穿(chuan)的(de)(de)臨界(jie)點上。工頻(pin)供(gong)電(dian)(dian)情況下，西(xi)門(men)子(zi)(zi)電(dian)(dian)機(ji)(ji)繞(rao)組(zu)(zu)輸入的(de)(de)是三(san)相50Hz的(de)(de)正弦波電(dian)(dian)壓(ya)，繞(rao)組(zu)(zu)產(chan)生(sheng)的(de)(de)感(gan)生(sheng)電(dian)(dian)壓(ya)也較低，線路中的(de)(de)浪涌分量較小，西(xi)門(men)子(zi)(zi)電(dian)(dian)機(ji)(ji)絕(jue)(jue)緣(yuan)程(cheng)度(du)的(de)(de)降低，也許只是帶來了并(bing)不起眼的(de)(de)“漏電(dian)(dian)流”，但繞(rao)組(zu)(zu)的(de)(de)匝間(jian)和(he)相間(jian)，還(huan)未(wei)能產(chan)生(sheng)電(dian)(dian)壓(ya)擊穿(chuan)現(xian)象，電(dian)(dian)機(ji)(ji)還(huan)在“正常運(yun)行(xing)”。應該說，隨著(zhu)絕(jue)(jue)緣(yuan)老(lao)化程(cheng)度(du)的(de)(de)進一(yi)步加深(shen)，即使(shi)還(huan)是在工頻(pin)供(gong)電(dian)(dian)情況下，相信在不遠的(de)(de)將來，該臺電(dian)(dian)機(ji)(ji)終會因(yin)絕(jue)(jue)緣(yuan)老(lao)化造成(cheng)相間(jian)或(huo)繞(rao)組(zu)(zu)間(jian)的(de)(de)電(dian)(dian)壓(ya)擊穿(chuan)而燒毀。但問題是，現(xian)在并(bing)沒有燒毀。

接入(ru)西門子(zi)變(bian)(bian)頻器后，西門子(zi)電(dian)(dian)(dian)機(ji)的(de)供電(dian)(dian)(dian)條件由此變(bian)(bian)得“惡劣”了(le)(le)：變(bian)(bian)頻器輸(shu)出的(de)PWM波形，實為(wei)數kHz乃至十幾(ji)kHz的(de)載波電(dian)(dian)(dian)壓，在(zai)電(dian)(dian)(dian)機(ji)繞(rao)組供電(dian)(dian)(dian)回(hui)路中，還會產生(sheng)各種分量的(de)諧波電(dian)(dian)(dian)壓。由電(dian)(dian)(dian)感(gan)特性可(ke)知(zhi)，流過電(dian)(dian)(dian)感(gan)電(dian)(dian)(dian)流的(de)變(bian)(bian)化速(su)度(du)越快，電(dian)(dian)(dian)感(gan)的(de)感(gan)生(sheng)電(dian)(dian)(dian)壓也越高。電(dian)(dian)(dian)機(ji)繞(rao)組的(de)感(gan)生(sheng)電(dian)(dian)(dian)壓比工(gong)頻供電(dian)(dian)(dian)時(shi)升(sheng)高了(le)(le)。在(zai)工(gong)頻供電(dian)(dian)(dian)時(shi)暴露(lu)不出的(de)絕緣缺陷，因不耐高頻載波下感(gan)生(sheng)電(dian)(dian)(dian)壓的(de)沖擊(ji)，于是繞(rao)組匝間(jian)或相間(jian)的(de)電(dian)(dian)(dian)壓擊(ji)穿(chuan)產生(sheng)了(le)(le)。電(dian)(dian)(dian)機(ji)繞(rao)組的(de)由相間(jian)、匝間(jian)短路造成了(le)(le)電(dian)(dian)(dian)機(ji)繞(rao)組的(de)突然短路，在(zai)運行中——模塊炸掉(diao)了(le)(le)，電(dian)(dian)(dian)機(ji)燒(shao)毀了(le)(le)。

西(xi)門(men)子(zi)變(bian)(bian)頻(pin)器在(zai)(zai)起動(dong)(dong)(dong)初始階段，因輸出頻(pin)率和(he)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)均(jun)在(zai)(zai)較低(di)的(de)幅(fu)值(zhi)內，負載電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)存在(zai)(zai)故障時(shi)，雖造成較大的(de)輸出電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)，但此(ci)(ci)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)往(wang)往(wang)在(zai)(zai)額定值(zhi)以(yi)內，電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)檢(jian)測電(dian)(dian)(dian)(dian)(dian)(dian)路及時(shi)動(dong)(dong)(dong)作，變(bian)(bian)頻(pin)器實(shi)施保護停機(ji)動(dong)(dong)(dong)作，模(mo)塊(kuai)(kuai)無炸(zha)毀之(zhi)虞。但若在(zai)(zai)全(quan)速（或近于(yu)全(quan)速）運(yun)行情況(kuang)下，三相輸出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)與頻(pin)率均(jun)達較高的(de)幅(fu)值(zhi)，此(ci)(ci)時(shi)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)繞組若有電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)擊(ji)穿現象，會于(yu)瞬間形成極大的(de)浪(lang)涌(yong)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)，則逆變(bian)(bian)模(mo)塊(kuai)(kuai)在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)檢(jian)測電(dian)(dian)(dian)(dian)(dian)(dian)路動(dong)(dong)(dong)作之(zhi)前，已經(jing)無法(fa)承受(shou)而炸(zha)裂損壞了。

由此(ci)(ci)看出(chu)，保(bao)護(hu)(hu)電(dian)(dian)(dian)路(lu)不(bu)是(shi)萬能的(de)(de)，任何保(bao)護(hu)(hu)電(dian)(dian)(dian)路(lu)都(dou)有它的(de)(de)“軟(ruan)肋(lei)”所在。西門子(zi)變頻器(qi)對(dui)(dui)全速運(yun)行中，西門子(zi)電(dian)(dian)(dian)機(ji)繞組(zu)的(de)(de)突(tu)(tu)發性(xing)電(dian)(dian)(dian)壓(ya)擊(ji)穿現(xian)(xian)象，是(shi)無能為力的(de)(de)，起不(bu)到有效保(bao)護(hu)(hu)作用的(de)(de)。變頻器(qi)保(bao)護(hu)(hu)電(dian)(dian)(dian)路(lu)，任何電(dian)(dian)(dian)機(ji)保(bao)護(hu)(hu)器(qi)，對(dui)(dui)此(ci)(ci)類突(tu)(tu)發故障(zhang)，都(dou)不(bu)能實(shi)施有效的(de)(de)保(bao)護(hu)(hu)。此(ci)(ci)類突(tu)(tu)發故障(zhang)出(chu)現(xian)(xian)時，只能宣告(gao)：該臺電(dian)(dian)(dian)機(ji)確實(shi)已經(jing)“壽終正寢”了。

此類故障對西門子變頻器的(de)逆變輸出模塊(kuai)是致命(ming)的(de)打擊，無可逃避的(de)。

其它由供電或負(fu)載(zai)(zai)方面引起的(de)(de)原因，如過(guo)、欠壓、負(fu)載(zai)(zai)重、甚至堵轉引起的(de)(de)過(guo)流等故障(zhang)，在西(xi)門子變頻(pin)器的(de)(de)保(bao)護電路正常(chang)的(de)(de)前提(ti)下，是能(neng)有效保(bao)護模(mo)塊安全(quan)的(de)(de)，模(mo)塊的(de)(de)損壞機率將大為減小(xiao)。

西門子SIEMENS變頻器