一、壓力變送器的工作原理及用途
壓力變送器是一種將壓力轉換成氣動信號或電動信號進行控制和遠傳的設備,它能將測壓元件傳感器感受到的氣體、液體等物理壓力參數轉變成標準的電信號(如4~20mADC等),以供給指示報警儀、記錄儀、調節器等二次儀表進行測量、指示和過程調節。壓力變送器的原理是:被測介質的兩種壓力通入高、低兩壓力室,低壓室壓力采用大氣壓或真空,作用在δ元(即敏感元件)的兩側隔離膜片上,通過隔離片和元件內的填充液傳送到測量膜片兩側,當兩側壓力不一致時,致使測量膜片產生位移,其位移量和壓力差成正比,故兩側電容量就不等,通過振蕩和解調環節,轉換成與壓力成正比的信號。壓力變送器廣泛應用于各種工業自控環境,包括水利水電、鐵路交通、智能建筑、生產自控、航空航天、軍工、石化、油井、電力、船舶、機床、管道等眾多行業。如果您想購買壓力變送器,可以先來了解一下壓力變送器十大品牌。
二、壓力變送器如何校準
1、校準前的準備工作不管是哪種壓力變送器,校準前都要做好準備工作,包括:壓力源通過膠皮管與自制接頭相連接,關閉平衡閥門,并檢查氣路密封情況,然后把電流表(電壓表)、手操器接入變送器輸出電路中,通電預熱后開始校準。2、校準操作:(1)常規壓力變送器的校準:先將阻(zu)尼調(diao)(diao)(diao)至零(ling)(ling)狀態,先調(diao)(diao)(diao)零(ling)(ling)點,然(ran)后(hou)加(jia)(jia)滿(man)度壓(ya)力(li)調(diao)(diao)(diao)滿(man)量程(cheng)(cheng),使(shi)輸出為20毫安(an)(an),在現場調(diao)(diao)(diao)校(xiao)講的(de)(de)(de)是快,在此介紹零(ling)(ling)點、量程(cheng)(cheng)的(de)(de)(de)快速調(diao)(diao)(diao)校(xiao)法。調(diao)(diao)(diao)零(ling)(ling)點時對滿(man)度幾乎沒有影響(xiang),但調(diao)(diao)(diao)滿(man)度時對零(ling)(ling)點有影響(xiang),在不帶遷移時其(qi)影響(xiang)約為量程(cheng)(cheng)調(diao)(diao)(diao)整(zheng)量的(de)(de)(de)1/5,即量程(cheng)(cheng)向上調(diao)(diao)(diao)整(zheng)1毫安(an)(an),零(ling)(ling)點將向上移動約0.2毫安(an)(an),反(fan)之亦(yi)然(ran)。(2)智能(neng)壓(ya)力(li)變送(song)器的(de)(de)(de)校(xiao)準(zhun):a)先做(zuo)一次(ci)4-20毫安(an)(an)微調(diao)(diao)(diao),用以校(xiao)正變送(song)器內(nei)部(bu)的(de)(de)(de)D/A轉(zhuan)換器,由于(yu)其(qi)不涉(she)及(ji)傳感部(bu)件,無需(xu)外部(bu)壓(ya)力(li)信號(hao)源(yuan)。b)再做(zuo)一次(ci)全程(cheng)(cheng)微調(diao)(diao)(diao),使(shi)4-20毫安(an)(an)、數字讀數與(yu)實(shi)際施加(jia)(jia)的(de)(de)(de)壓(ya)力(li)信號(hao)相(xiang)吻合,因此需(xu)要壓(ya)力(li)信號(hao)源(yuan)。c)最后(hou)做(zuo)重定量程(cheng)(cheng),通過(guo)調(diao)(diao)(diao)整(zheng)使(shi)模(mo)擬(ni)輸出4-20毫安(an)(an)與(yu)外加(jia)(jia)的(de)(de)(de)壓(ya)力(li)信號(hao)源(yuan)相(xiang)吻合,其(qi)作用與(yu)變送(song)器外殼上的(de)(de)(de)調(diao)(diao)(diao)零(ling)(ling)(Z)、調(diao)(diao)(diao)量程(cheng)(cheng)(R)開關(guan)的(de)(de)(de)作用完全相(xiang)同。
三、壓力變送器接線方法
壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi)是將(jiang)壓(ya)力(li)(li)(li)信(xin)號轉換為模(mo)(mo)(mo)擬量信(xin)號或者(zhe)數字量信(xin)號的(de)轉換設備,一般除無(wu)線(xian)(xian)(xian)壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi)外(wai),其他的(de)都(dou)是接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)使用的(de),壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi)的(de)接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)一般有三(san)種(zhong):兩線(xian)(xian)(xian)制(zhi)(zhi)、三(san)線(xian)(xian)(xian)制(zhi)(zhi)、四線(xian)(xian)(xian)制(zhi)(zhi),壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi)需要連(lian)(lian)(lian)接(jie)(jie)(jie)(jie)的(de)連(lian)(lian)(lian)線(xian)(xian)(xian)有幾(ji)根連(lian)(lian)(lian)線(xian)(xian)(xian),就是幾(ji)線(xian)(xian)(xian)制(zhi)(zhi)的(de)接(jie)(jie)(jie)(jie)法:1、二(er)線(xian)(xian)(xian)制(zhi)(zhi)的(de)壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi),+極(ji)出(chu)(chu)(chu)來(lai)接(jie)(jie)(jie)(jie)PLC AI 模(mo)(mo)(mo)塊(kuai)(kuai)的(de)-;-極(ji)出(chu)(chu)(chu)來(lai)接(jie)(jie)(jie)(jie)PLC AI 模(mo)(mo)(mo)塊(kuai)(kuai)的(de)+。2、三(san)線(xian)(xian)(xian)制(zhi)(zhi)的(de)壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi),信(xin)號+出(chu)(chu)(chu)來(lai)接(jie)(jie)(jie)(jie)PLC AI 模(mo)(mo)(mo)塊(kuai)(kuai)的(de)+;公用-出(chu)(chu)(chu)來(lai)接(jie)(jie)(jie)(jie)PLC AI 模(mo)(mo)(mo)塊(kuai)(kuai)的(de)-;剩下的(de)24dc+接(jie)(jie)(jie)(jie)24v電(dian)源(yuan)+。3、四線(xian)(xian)(xian)制(zhi)(zhi)的(de)壓(ya)力(li)(li)(li)變(bian)(bian)(bian)送(song)器(qi)(qi)(qi),信(xin)號+出(chu)(chu)(chu)來(lai)接(jie)(jie)(jie)(jie)PLC AI 模(mo)(mo)(mo)塊(kuai)(kuai)的(de)+;信(xin)號-出(chu)(chu)(chu)來(lai)接(jie)(jie)(jie)(jie)PLC AI 模(mo)(mo)(mo)塊(kuai)(kuai)的(de)-;剩下的(de)24dc+接(jie)(jie)(jie)(jie)24v電(dian)源(yuan)+;24dc-接(jie)(jie)(jie)(jie)24v電(dian)源(yuan)-。
四、壓力變送器精度是多少
任何儀表(biao)都有(you)(you)一(yi)定(ding)的誤(wu)差(cha),使(shi)用(yong)儀表(biao)時必須先知(zhi)道該儀表(biao)的精(jing)確程度(du)(du),以便估計(ji)測(ce)量結果(guo)與(yu)約定(ding)真(zhen)值的差(cha)距,即估計(ji)測(ce)量值的大小(xiao),按(an)儀表(biao)工業規定(ding),儀表(biao)的精(jing)確度(du)(du)劃(hua)分成若干等(deng)級(ji)(ji)(ji),簡稱(cheng)精(jing)度(du)(du)等(deng)級(ji)(ji)(ji),如0.1級(ji)(ji)(ji)、0.2級(ji)(ji)(ji)、0.5級(ji)(ji)(ji)、1.0級(ji)(ji)(ji)、1.5級(ji)(ji)(ji)、2.5級(ji)(ji)(ji)等(deng),精(jing)度(du)(du)等(deng)級(ji)(ji)(ji)的數字越小(xiao),精(jing)度(du)(du)越高。壓(ya)(ya)力(li)變(bian)(bian)送(song)(song)器(qi)(qi)有(you)(you)多種,精(jing)度(du)(du)等(deng)級(ji)(ji)(ji)有(you)(you)所不同,一(yi)般(ban)小(xiao)巧型的壓(ya)(ya)力(li)變(bian)(bian)送(song)(song)器(qi)(qi)、2088壓(ya)(ya)力(li)變(bian)(bian)送(song)(song)器(qi)(qi)、液位(wei)變(bian)(bian)送(song)(song)器(qi)(qi)為0.5/0.25級(ji)(ji)(ji),電容(rong)式壓(ya)(ya)力(li)變(bian)(bian)送(song)(song)器(qi)(qi)為0.2級(ji)(ji)(ji),單(dan)晶(jing)硅壓(ya)(ya)力(li)變(bian)(bian)送(song)(song)器(qi)(qi)為0.1/0.075級(ji)(ji)(ji)。