一、壓力變送器是幾線制
壓力變送器是將壓力信號轉換為模擬量信號或者數字量信號的轉換設備,一般除無線壓力變送器外,其(qi)他的(de)(de)都是接(jie)(jie)線(xian)(xian)(xian)(xian)使(shi)用(yong)的(de)(de),壓力變送(song)器(qi)的(de)(de)接(jie)(jie)線(xian)(xian)(xian)(xian)一(yi)般有三種:兩(liang)線(xian)(xian)(xian)(xian)制(zhi)、三線(xian)(xian)(xian)(xian)制(zhi)、四線(xian)(xian)(xian)(xian)制(zhi),壓力變送(song)器(qi)需要連接(jie)(jie)的(de)(de)連線(xian)(xian)(xian)(xian)有幾(ji)(ji)根連線(xian)(xian)(xian)(xian),就是幾(ji)(ji)線(xian)(xian)(xian)(xian)制(zhi)的(de)(de)接(jie)(jie)法:
1、兩線制
兩線制(zhi)壓力(li)(li)變送(song)器(qi)是(shi)最常(chang)用的(de)(de),兩根(gen)線組成一(yi)條(tiao)回路(lu)(lu),這條(tiao)回路(lu)(lu)既是(shi)為壓力(li)(li)變送(song)器(qi)提供(gong)電(dian)(dian)源支持(chi)的(de)(de)回路(lu)(lu),也是(shi)傳輸電(dian)(dian)流信(xin)號(hao)的(de)(de)回路(lu)(lu)。也就是(shi)說在兩線制(zhi)接線中,壓力(li)(li)變送(song)器(qi)的(de)(de)輸出(chu)的(de)(de)負載和電(dian)(dian)源是(shi)被串(chuan)聯(lian)在一(yi)起(qi)的(de)(de)。使用這種連接方式(shi)的(de)(de)通常(chang)都是(shi)輸出(chu)電(dian)(dian)流信(xin)號(hao)的(de)(de)壓力(li)(li)變送(song)器(qi),如4~20mA的(de)(de)標準電(dian)(dian)控信(xin)號(hao),當二線制(zhi)需要輸出(chu)電(dian)(dian)壓值時,可以通過(guo)串(chuan)聯(lian)電(dian)(dian)阻的(de)(de)方式(shi)取壓測得(de),如4-20mA電(dian)(dian)流電(dian)(dian)路(lu)(lu)中串(chuan)聯(lian)250Ω電(dian)(dian)阻。
2、三線制
三(san)線(xian)(xian)制壓(ya)(ya)(ya)力(li)變(bian)送(song)器將電(dian)(dian)源(yuan)正(zheng)端(duan)(duan)和信號(hao)(hao)輸出(chu)的正(zheng)端(duan)(duan)分離(li),但它(ta)們另一個接(jie)線(xian)(xian)端(duan)(duan)子卻是(shi)(shi)用(yong)(yong)同一根線(xian)(xian)連接(jie)的。在這(zhe)種情(qing)況(kuang)下,電(dian)(dian)流(liu)實(shi)際(ji)的通路(lu)還(huan)是(shi)(shi)由電(dian)(dian)源(yuan)正(zheng)負極的連線(xian)(xian)所組(zu)成(cheng)的回(hui),信號(hao)(hao)正(zheng)端(duan)(duan)的電(dian)(dian)流(liu)接(jie)近為0,只能傳遞電(dian)(dian)位電(dian)(dian)壓(ya)(ya)(ya),可(ke)以理解(jie)為萬(wan)用(yong)(yong)表的電(dian)(dian)壓(ya)(ya)(ya)檔,負載(zai)無限大近似(si)斷路(lu)。使用(yong)(yong)這(zhe)種連接(jie)方式(shi)的都是(shi)(shi)輸出(chu)電(dian)(dian)壓(ya)(ya)(ya)信號(hao)(hao)的壓(ya)(ya)(ya)力(li)變(bian)送(song)器1~10V,1~5V,0~5V等標準控制信號(hao)(hao)。
3、四線制
四線制不(bu)同于二線制與(yu)三線制,它由(you)兩(liang)個獨(du)立的回路(lu)組成,彼此互不(bu)干擾。因為(wei)輸出(chu)電(dian)路(lu)的獨(du)立,使(shi)得它無論式輸出(chu)電(dian)壓信(xin)號還是電(dian)流信(xin)號都可以做(zuo)到。
二、壓力變送器接線怎么接
壓力變送器接線(xian)制(zhi)不同,接線(xian)方(fang)法也有(you)所不同:
1、二線制的壓力變送器,+極出(chu)來接(jie)PLC AI 模(mo)塊的-;-極出(chu)來接(jie)PLC AI 模(mo)塊的+。
2、三(san)線(xian)制的(de)(de)壓力變送器,信號+出來接(jie)(jie)PLC AI 模(mo)塊的(de)(de)+;公用(yong)-出來接(jie)(jie)PLC AI 模(mo)塊的(de)(de)-;剩(sheng)下(xia)的(de)(de)24dc+接(jie)(jie)24v電源(yuan)+。
3、四線制(zhi)的壓力變送器,信(xin)號+出(chu)來接(jie)PLC AI 模塊的+;信(xin)號-出(chu)來接(jie)PLC AI 模塊的-;剩下(xia)的24dc+接(jie)24v電源+;24dc-接(jie)24v電源-。
三、壓力變送器接線注意事項
壓力變送器電(dian)(dian)源(yuan)(yuan)有交流(liu)和直(zhi)流(liu)之分(fen)(fen)(fen),交流(liu)分(fen)(fen)(fen)為220V和110V兩種,直(zhi)流(liu)分(fen)(fen)(fen)為固(gu)定電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)和寬(kuan)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)之分(fen)(fen)(fen),固(gu)定電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)比如5V、10V、12V、24V等(deng)固(gu)定電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)這(zhe)樣的(de)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)選擇(ze)(ze)電(dian)(dian)源(yuan)(yuan)時(shi),一定要(yao)按照標稱電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)來選電(dian)(dian)源(yuan)(yuan)。寬(kuan)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)比如3-36V、5-24V等(deng)這(zhe)樣的(de)標稱,電(dian)(dian)源(yuan)(yuan)選擇(ze)(ze)在(zai)(zai)這(zhe)個范圍內的(de)就可以了,接(jie)線(xian)時(shi)注意電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)等(deng)級(ji),直(zhi)流(liu)電(dian)(dian)源(yuan)(yuan)的(de)正負(fu)極不(bu)要(yao)接(jie)錯。系統中如果(guo)有兩塊不(bu)同電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)電(dian)(dian)源(yuan)(yuan)注意電(dian)(dian)源(yuan)(yuan)共問題(ti),就是兩個電(dian)(dian)源(yuan)(yuan)負(fu)極要(yao)接(jie)在(zai)(zai)一起。