隔離(li)(li)式安全柵除具(ju)有限(xian)壓(ya)與限(xian)流的(de)作用(yong)之外，還帶有電(dian)(dian)(dian)流隔離(li)(li)的(de)功能(neng)(neng)。隔離(li)(li)柵通(tong)常由回(hui)路(lu)限(xian)能(neng)(neng)單(dan)元(yuan)(yuan)(yuan)、電(dian)(dian)(dian)流隔離(li)(li)單(dan)元(yuan)(yuan)(yuan)和(he)信(xin)號處理單(dan)元(yuan)(yuan)(yuan)三部分組成(cheng)，基本功能(neng)(neng)電(dian)(dian)(dian)路(lu)如圖(tu)2所(suo)示。回(hui)路(lu)限(xian)能(neng)(neng)單(dan)元(yuan)(yuan)(yuan)為安全柵的(de)核(he)心部分。此外，輔助有用(yong)于驅動現場(chang)儀(yi)表(biao)的(de)回(hui)路(lu)供電(dian)(dian)(dian)電(dian)(dian)(dian)路(lu)和(he)用(yong)于儀(yi)表(biao)信(xin)號采集的(de)檢測電(dian)(dian)(dian)路(lu)。信(xin)號處理單(dan)元(yuan)(yuan)(yuan)則根據安全柵的(de)功能(neng)(neng)要求進行信(xin)號處理。

工業(ye)現場(chang)一(yi)(yi)般需要(yao)采用兩(liang)線制傳輸方式的(de)(de)(de)配電(dian)(dian)(dian)(dian)器(qi)，既要(yao)為諸(zhu)如壓(ya)力變送器(qi)等一(yi)(yi)次儀(yi)表提供24V 配電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)源，同(tong)時又(you)要(yao)對(dui)輸入(ru)的(de)(de)(de)電(dian)(dian)(dian)(dian)流(liu)信號進(jin)(jin)行采集、放大、運算、和(he)進(jin)(jin)行抗干擾處理后(hou)，再輸出隔(ge)離的(de)(de)(de)電(dian)(dian)(dian)(dian)流(liu)和(he)電(dian)(dian)(dian)(dian)壓(ya)信號，供后(hou)面的(de)(de)(de)二次儀(yi)表或其(qi)它儀(yi)表使用。 但一(yi)(yi)些特殊的(de)(de)(de)工業(ye)現場(chang)不但需要(yao)兩(liang)線制傳輸，既提供配電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)源又(you)有信號隔(ge)離功能，同(tong)時還(huan)需要(yao)具有安(an)(an)全火花(hua)型(xing)防(fang)爆(bao)的(de)(de)(de)性(xing)能，可靠地(di)防(fang)止電(dian)(dian)(dian)(dian)源高壓(ya)與信號之間的(de)(de)(de)混觸，利用電(dian)(dian)(dian)(dian)流(liu)、電(dian)(dian)(dian)(dian)壓(ya)雙重化限(xian)(xian)制回路，把進(jin)(jin)入(ru)危險(xian)場(chang)所的(de)(de)(de)能量限(xian)(xian)制在安(an)(an)全定額(e)以下的(de)(de)(de)具有特殊功能的(de)(de)(de)配電(dian)(dian)(dian)(dian)器(qi)—安(an)(an)全柵。

隔離(li)式(shi)安(an)全(quan)(quan)(quan)柵(zha)，基本有檢測(ce)端安(an)全(quan)(quan)(quan)柵(zha)和操作端安(an)全(quan)(quan)(quan)柵(zha)兩種(zhong)類型。檢測(ce)端安(an)全(quan)(quan)(quan)柵(zha)與(yu)兩線制變送器(qi)配套使用；操作端安(an)全(quan)(quan)(quan)柵(zha)與(yu)電(dian)氣(qi)轉換器(qi)或電(dian)氣(qi)閥門配套使用。也有信號輸(shu)入等(deng)類型隔離(li)式(shi)安(an)全(quan)(quan)(quan)柵(zha)。

由于隔離式安(an)全柵采用了限壓、限流、隔離等措(cuo)施，不僅能(neng)防(fang)止危險能(neng)量(liang)從本(ben)安(an)端子進入危險現場，提高系(xi)統的本(ben)安(an)防(fang)爆(bao)性能(neng)，而且還增加(jia)了系(xi)統的抗(kang)干擾能(neng)力(li)，大大提高了系(xi)統運行的可靠性。