變(bian)頻內(nei)部(bu)的(de)(de)壓力變(bian)化可(ke)以實(shi)現電(dian)(dian)器(qi)元件的(de)(de)運轉，變(bian)頻的(de)(de)損(sun)壞相應也會(hui)影響到(dao)半導體器(qi)件，嚴重的(de)(de)話會(hui)導致元器(qi)件損(sun)毀(hui)。靜電(dian)(dian)放電(dian)(dian)和(he)電(dian)(dian)快(kuai)速瞬變(bian)脈沖(chong)群(qun)對變(bian)頻器(qi)系(xi)統(tong)會(hui)產生不(bu)同程度的(de)(de)危害。無錫變(bian)頻器(qi)當電(dian)(dian)纜暴露在4～8kv靜電(dian)(dian)放電(dian)(dian)環境中時，信息(xi)傳輸電(dian)(dian)纜終端負載(zai)上可(ke)以測量(liang)到(dao)的(de)(de)感(gan)應電(dian)(dian)壓可(ke)達到(dao)600v，這個(ge)電(dian)(dian)壓遠(yuan)遠(yuan)超出了(le)變(bian)頻器(qi)輸入、輸出端口和(he)通信端口的(de)(de)門(men)限電(dian)(dian)壓值，典型的(de)(de)感(gan)應脈沖(chong)持(chi)續時間大約為(wei)400ns。

1.防雷端口

根據變頻(pin)器(qi)應用的(de)(de)工程實踐，變頻(pin)器(qi)受雷擊(ji)可大致分為(wei)直(zhi)擊(ji)雷、感應雷和傳導(dao)雷。但不論(lun)以(yi)哪一種形式(shi)到達設備都可歸納為(wei)從以(yi)下4個部(bu)位(wei)侵入的(de)(de)雷電(dian)浪涌，在此把這些部(bu)位(wei)稱為(wei)防雷端口，并以(yi)變頻(pin)器(qi)舉例說(shuo)明(ming)。

2. 外(wai)殼(ke)端口

比(bi)如(ru)(ru)說，我們可(ke)(ke)(ke)以把任何(he)一個(ge)(ge)大的(de)(de)(de)或小(xiao)的(de)(de)(de)變(bian)頻器(qi)或系(xi)(xi)(xi)統(tong)視為一個(ge)(ge)整體的(de)(de)(de)外殼，如(ru)(ru)傳(chuan)(chuan)感器(qi)、傳(chuan)(chuan)輸(shu)(shu)線(xian)、信號(hao)中(zhong)繼、現(xian)場儀表、dcs系(xi)(xi)(xi)統(tong)等，它(ta)們都有(you)可(ke)(ke)(ke)能完(wan)全暴露在環境中(zhong)受到直接雷(lei)(lei)擊，造(zao)成(cheng)設(she)備損壞。標準規定，當(dang)設(she)備外殼受到4kv的(de)(de)(de)雷(lei)(lei)電(dian)(dian)靜電(dian)(dian)放(fang)(fang)電(dian)(dian)時，都會影響變(bian)頻器(qi)或系(xi)(xi)(xi)統(tong)的(de)(de)(de)正(zheng)常運行。例(li)如(ru)(ru)放(fang)(fang)置于室外輸(shu)(shu)入變(bian)頻器(qi)的(de)(de)(de)傳(chuan)(chuan)感器(qi)有(you)可(ke)(ke)(ke)能受到雷(lei)(lei)電(dian)(dian)接觸放(fang)(fang)電(dian)(dian);位于室內(nei)的(de)(de)(de)變(bian)頻器(qi)柜有(you)可(ke)(ke)(ke)能受到建(jian)筑物(wu)避雷(lei)(lei)引線(xian)泄流時的(de)(de)(de)空(kong)3.信號(hao)線(xian)端口

在變(bian)(bian)頻(pin)器(qi)(qi)(qi)控制系(xi)統中,為了實現信號或信息的(de)(de)傳遞總要有與外界連(lian)接的(de)(de)部(bu)位(wei),那么這些從外界輸入(ru)信號或變(bian)(bian)頻(pin)器(qi)(qi)(qi)輸出的(de)(de)信號接口都有可能受(shou)(shou)到(dao)(dao)雷電(dian)浪(lang)涌(yong)(yong)沖(chong)擊。因(yin)為變(bian)(bian)頻(pin)器(qi)(qi)(qi)柜外部(bu)信號輸入(ru)變(bian)(bian)頻(pin)器(qi)(qi)(qi)端(duan)(duan)口的(de)(de)浪(lang)涌(yong)(yong)往往通過(guo)(guo)長電(dian)纜(lan)，所以采用10/700μs波形，標準規定線(xian)到(dao)(dao)線(xian)間(jian)浪(lang)涌(yong)(yong)電(dian)壓(ya)(ya)為0.5kv，線(xian)到(dao)(dao)地間(jian)浪(lang)涌(yong)(yong)電(dian)壓(ya)(ya)為1kv。而樓內變(bian)(bian)頻(pin)器(qi)(qi)(qi)之(zhi)間(jian)傳遞信號的(de)(de)端(duan)(duan)口受(shou)(shou)到(dao)(dao)浪(lang)涌(yong)(yong)沖(chong)擊相當(dang)于電(dian)源(yuan)線(xian)上的(de)(de)浪(lang)涌(yong)(yong)沖(chong)擊，采用1.2/50(8/20)μs組合波，線(xian)到(dao)(dao)線(xian)、線(xian)到(dao)(dao)地浪(lang)涌(yong)(yong)電(dian)壓(ya)(ya)限值(zhi)不變(bian)(bian)。一(yi)旦超過(guo)(guo)限值(zhi)，信號端(duan)(duan)口和端(duan)(duan)口后的(de)(de)設備有可能遭受(shou)(shou)損壞(huai)。

電(dian)(dian)(dian)(dian)壓的瞬息萬(wan)變(bian)(bian)(bian)，變(bian)(bian)(bian)頻(pin)(pin)器(qi)的內部信(xin)號變(bian)(bian)(bian)化容易造成變(bian)(bian)(bian)頻(pin)(pin)器(qi)標準規(gui)定。從而(er)導(dao)致變(bian)(bian)(bian)頻(pin)(pin)器(qi)內部電(dian)(dian)(dian)(dian)子器(qi)件(jian)(jian)的損(sun)(sun)壞，損(sun)(sun)壞的現(xian)象是(shi)(shi)使變(bian)(bian)(bian)頻(pin)(pin)器(qi)中的半導(dao)體(ti)器(qi)件(jian)(jian)(包括二極管(guan)(guan)、晶(jing)體(ti)管(guan)(guan)、晶(jing)閘管(guan)(guan)和集成電(dian)(dian)(dian)(dian)路等)被燒毀或(huo)擊(ji)穿(chuan)。據統計(ji)變(bian)(bian)(bian)頻(pin)(pin)器(qi)控制(zhi)部分的故障(zhang)有75%是(shi)(shi)由于瞬變(bian)(bian)(bian)和浪(lang)涌(yong)造成的。電(dian)(dian)(dian)(dian)壓的瞬變(bian)(bian)(bian)和浪(lang)涌(yong)無處不在(zai)，電(dian)(dian)(dian)(dian)網(wang)、雷擊(ji)、爆(bao)破，就連人在(zai)地毯上行(xing)走(zou)都(dou)(dou)會產生上萬(wan)伏(fu)的靜電(dian)(dian)(dian)(dian)感應電(dian)(dian)(dian)(dian)壓，這些，都(dou)(dou)是(shi)(shi)變(bian)(bian)(bian)頻(pin)(pin)器(qi)控制(zhi)端口和通信(xin)端口的隱形危(wei)害(hai)源。因此，為了提高變(bian)(bian)(bian)頻(pin)(pin)器(qi)的可靠性就必須對電(dian)(dian)(dian)(dian)壓瞬變(bian)(bian)(bian)和浪(lang)涌(yong)采取防護措施。

2.3 電(dian)源(yuan)端口(kou)

電(dian)(dian)源端口是(shi)分布最廣泛也最容易(yi)感應或(huo)傳導雷電(dian)(dian)浪(lang)(lang)涌(yong)(yong)的部位，變(bian)(bian)頻器(qi)(qi)的電(dian)(dian)源端口為(wei)從配(pei)電(dian)(dian)屏到變(bian)(bian)頻器(qi)(qi)電(dian)(dian)源輸(shu)入(ru)端和從變(bian)(bian)頻器(qi)(qi)輸(shu)出端到電(dian)(dian)動機。標準規定(ding)在1.2/50(8/20)μs 波(bo)形下線與(yu)線之(zhi)間浪(lang)(lang)涌(yong)(yong)電(dian)(dian)壓(ya)限值為(wei)0.5kv，線到地浪(lang)(lang)涌(yong)(yong)電(dian)(dian)壓(ya)限制為(wei)1kv。但這(zhe)里的浪(lang)(lang)涌(yong)(yong)電(dian)(dian)壓(ya)是(shi)指明工作電(dian)(dian)壓(ya)為(wei)220v交流進(jin)入(ru)的，如(ru)果(guo)工作電(dian)(dian)壓(ya)較低則不能以此(ci)為(wei)標準，電(dian)(dian)源線上(shang)受較小的浪(lang)(lang)涌(yong)(yong)沖擊不一定(ding)立即損(sun)壞設備，但至(zhi)少(shao)對壽(shou)命有影響。