低壓電容補償柜是目前常(chang)見的無功(gong)補(bu)(bu)償(chang)裝置,用(yong)(yong)于電(dian)(dian)(dian)力系(xi)統中(zhong)提高功(gong)率(lv)因數。在電(dian)(dian)(dian)力系(xi)統中(zhong),用(yong)(yong)電(dian)(dian)(dian)設備會在使(shi)用(yong)(yong)時過(guo)程中(zhong)產生無功(gong)功(gong)率(lv),而且通(tong)常(chang)表示(shi)為電(dian)(dian)(dian)感性,它會使(shi)電(dian)(dian)(dian)源容(rong)量(liang)的使(shi)用(yong)(yong)效率(lv)降低,而通(tong)過(guo)在系(xi)統中(zhong)適當(dang)地增加(jia)電(dian)(dian)(dian)容(rong)的方式就可以(yi)得以(yi)改(gai)善。?電(dian)(dian)(dian)力電(dian)(dian)(dian)容(rong)補(bu)(bu)償(chang)也稱功(gong)率(lv)因數補(bu)(bu)償(chang)。電(dian)(dian)(dian)容(rong)器(qi)的投入和切(qie)(qie)除需要依靠電(dian)(dian)(dian)容(rong)器(qi)投切(qie)(qie)開關(guan)(guan),一般(ban)低壓(ya)補(bu)(bu)償(chang)柜的電(dian)(dian)(dian)容(rong)投切(qie)(qie)開關(guan)(guan)主要分為三(san)類:
切換電容接觸器:價格便宜,性能穩定。但投切時由涌流、過電壓、電弧,故觸點易燒結,一般使用于負荷穩定,投切次數較少的場合。
可控硅投切開關:投切時選擇交流值的(de)過零點,無(wu)涌(yong)流無(wu)弧光,可迅速跟蹤負荷(he)頻(pin)繁(fan)投切。配置獨(du)立風扇散熱,內置過溫(wen)保護,價格較高,一般應用于(yu)負荷(he)急劇變化的(de)需(xu)頻(pin)繁(fan)投切的(de)場合(he)。
復合開關:集合了接觸器和可控硅開關兩者的主(zhu)要(yao)優點并避(bi)免(mian)了其缺(que)點,價格較(jiao)高(gao),另外因其也內置了接觸器(qi),其響(xiang)應(ying)速度比(bi)可(ke)控(kong)硅要(yao)長些(xie),要(yao)求快速跟蹤投切的場(chang)合(he)一般并不適用(yong)。對于負荷電流變(bian)化較(jiao)大的場(chang)所,應(ying)采用(yong)動態補(bu)償,采用(yong)可(ke)控(kong)硅控(kong)制方式。
上面介紹了應用于低壓電容補償柜中的三種投切開關,雖然他們各自擁有優缺點,但是從實際應用來看,接觸器已經越來越少的被采用,而晶閘管開關因此投切速度快,適合頻繁投切等優勢,正日漸被大量企業所使用和推薦。