無(wu)負(fu)壓(ya)水(shui)(shui)(shui)(shui)箱內的(de)(de)(de)變頻泵以它的(de)(de)(de)轉速運(yun)行(xing)，利用自來水(shui)(shui)(shui)(shui)原有的(de)(de)(de)壓(ya)力(li)實(shi)現疊加，能使(shi)用戶所需的(de)(de)(de)壓(ya)力(li)和(he)壓(ya)力(li)恒定。變頻供(gong)水(shui)(shui)(shui)(shui)系統的(de)(de)(de)進水(shui)(shui)(shui)(shui)口(kou)與無(wu)負(fu)壓(ya)裝(zhuang)置(zhi)和(he)無(wu)負(fu)壓(ya)進水(shui)(shui)(shui)(shui)裝(zhuang)置(zhi)連(lian)接，通過無(wu)負(fu)壓(ya)裝(zhuang)置(zhi)的(de)(de)(de)開啟與停(ting)止(zhi)達到自來水(shui)(shui)(shui)(shui)管網不產生負(fu)壓(ya)，在(zai)無(wu)負(fu)壓(ya)裝(zhuang)置(zhi)起停(ting)的(de)(de)(de)同時，無(wu)負(fu)壓(ya)進水(shui)(shui)(shui)(shui)裝(zhuang)置(zhi)會(hui)做出(chu)與無(wu)負(fu)裝(zhuang)置(zhi)相反(fan)的(de)(de)(de)動作。

　　自來水(shui)(shui)管網停水(shui)(shui)無負壓裝置(zhi)自動(dong)關閉，水(shui)(shui)箱的無負壓進(jin)水(shui)(shui)裝置(zhi)自動(dong)打開，由水(shui)(shui)箱供水(shui)(shui)。

　　“變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)”是指沒(mei)有變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)或者(zhe)不產(chan)生變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)。而通常(chang)我(wo)們說的(de)“變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)”是指在(zai)大(da)氣(qi)(qi)壓(ya)(ya)狀態(tai)(tai)下(xia)低于(yu)常(chang)壓(ya)(ya)(即(ji)1個(ge)大(da)氣(qi)(qi)壓(ya)(ya))的(de)氣(qi)(qi)體壓(ya)(ya)力狀態(tai)(tai)或者(zhe)在(zai)密閉(bi)(bi)系(xi)(xi)(xi)統(tong)(tong)中低于(yu)環(huan)境壓(ya)(ya)力的(de)真空(kong)(kong)狀態(tai)(tai)，也稱真空(kong)(kong)。例如，用吸(xi)(xi)管(guan)喝飲料時(shi)，吸(xi)(xi)管(guan)里就(jiu)是變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong);水(shui)(shui)泵(beng)吸(xi)(xi)水(shui)(shui)，其(qi)葉輪進(jin)口處就(jiu)形成(cheng)變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong);密封的(de)食品罐(guan)頭開啟時(shi)聽到(dao)“嗤”的(de)一聲，也是變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)現象(xiang);自閉(bi)(bi)沖洗閥沖廁節(jie)水(shui)(shui)，則是利用虹吸(xi)(xi)變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong);鋼筆吸(xi)(xi)取墨水(shui)(shui)、生命呼吸(xi)(xi)等，也是利用變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)……密閉(bi)(bi)系(xi)(xi)(xi)統(tong)(tong)內(如容器、管(guan)道或封閉(bi)(bi)空(kong)(kong)間(jian))的(de)氣(qi)(qi)體壓(ya)(ya)力低于(yu)大(da)氣(qi)(qi)壓(ya)(ya)時(shi)，即(ji)產(chan)生變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)，其(qi)變(bian)(bian)(bian)頻(pin)(pin)供(gong)(gong)水(shui)(shui)系(xi)(xi)(xi)統(tong)(tong)大(da)小通常(chang)用“真空(kong)(kong)度(du)”表示。