J9九游会AG

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压力变送器和差压变送器的区别

2021-09-01 20:05
J9九游会AG仪器仪表
很多工业上(shang)的(de)朋友都分(fen)不清(qing)压力变送器和差压变送器的区别差压变送(song)器是(shi)(shi)测量变(bian)送(song)(song)器两端压力之差(cha)的(de)(de)变(bian)送(song)(song)器,输出标准信号(hao)(如 4~20mA、0~5V)。差(cha)压变(bian)送(song)(song)器与一般(ban)的(de)(de)压力变(bian)送(song)(song)器不同的(de)(de)是(shi)(shi)它(ta)们(men)均有(you)2个压力接口, 差(cha)压变(bian)送(song)(song)器一般(ban)分为正压端和负压端,一般(ban)情况下(xia), 差(cha)压变(bian)送(song)(song)器正压端的(de)(de)压力应(ying)大于负压段压力才能测量。
 
安装说明:
 
其实大家可(ke)(ke)能注意到, 4-20mA电(dian)(dian)(dian)流本身(shen)就可(ke)(ke)以为(wei)变(bian)送(song)(song)器(qi)(qi)(qi)供电(dian)(dian)(dian),变(bian)送(song)(song)器(qi)(qi)(qi)在电(dian)(dian)(dian)路中相当(dang)于(yu)一个特(te)殊的负载,特(te)殊之处(chu)在于(yu)变(bian)送(song)(song)器(qi)(qi)(qi)的耗电(dian)(dian)(dian)电(dian)(dian)(dian)流在4~20mA之间根据传感器(qi)(qi)(qi)输出而(er)变(bian)化。显示仪表(biao)只需(xu)要串在电(dian)(dian)(dian)路中即可(ke)(ke)。这(zhei)种变(bian)送(song)(song)器(qi)(qi)(qi)只需(xu)外(wai)接(jie)2根线(xian),因而(er)被称为(wei)两线(xian)制(zhi)变(bian)送(song)(song)器(qi)(qi)(qi)。工业电(dian)(dian)(dian)流环标准(zhun)下限为(wei)4mA,因此只要在量程范围(wei)内,变(bian)送(song)(song)器(qi)(qi)(qi)至少(shao)有(you)4mA供电(dian)(dian)(dian)。这(zhei)使得两线(xian)制(zhi)传感器(qi)(qi)(qi)的设(she)计成(cheng)为(wei)可(ke)(ke)能。
 
在工业应用中(zhong),测(ce)量(liang)点一般在现(xian)场,而(er)显示(shi)设备或者(zhe)控制(zhi)设备一般都在控制(zhi)室或控制(zhi)柜上。两(liang)者(zhe)之间(jian)距(ju)离可能数十至数百米。另外四线(xian)(xian)(xian)制(zhi)变送(song)器(qi)和三线(xian)(xian)(xian)制(zhi)变送(song)器(qi)因(yin)(yin)导线(xian)(xian)(xian)内电流不对称必(bi)须使(shi)用昂贵的屏蔽线(xian)(xian)(xian),而(er)两(liang)线(xian)(xian)(xian)制(zhi)变送(song)器(qi)可使(shi)用非常便宜(yi)的的双绞线(xian)(xian)(xian)导线(xian)(xian)(xian),因(yin)(yin)此在应用中(zhong)两(liang)线(xian)(xian)(xian)制(zhi)变送(song)器(qi)必(bi)然优先选(xuan)择。
 
差压(ya)变送器的工作原理:
 
差压变(bian)送(song)器通(tong)常(chang)用于测(ce)量密闭容器内的液位,利用液体自身重力产(chan)生的压力差来测(ce)量容器内液体的液位。其(qi)高压侧测(ce)量管(guan),由于蒸汽凝结,始终处于充满(man)水状态,保持(chi)压力恒(heng)定,而(er)低压侧测(ce)量管(guan),与容器组成(cheng)联(lian)通(tong)器,其(qi)压力随容器内液位的变(bian)化(hua)成(cheng)线性变(bian)化(hua)。 
 
设△P为(wei)变送(song)器接(jie)收到的(de)差压信号(hao),P0为(wei)容(rong)器内部压力(li),P+为(wei)变送(song)器正压侧压力(li),P-为(wei)变送(song)器负压侧压力(li);ρ为(wei)容(rong)器内液(ye)体的(de)密(mi)度(du);g为(wei)重力(li)加(jia)速度(du);h1为(wei)工艺(yi)零点(dian)到容(rong)器上部取压口(kou)的(de)高度(du);h2为(wei)容(rong)器工艺(yi)液(ye)位;h为(wei)变送(song)器到工艺(yi)液(ye)位零点(dian)的(de)高度(du)。 
 
3.前置放大器无频(pin)率(lv)输出。可(ke)更换前置放大器。
 
4.主旋进旋涡(wo)流(liu)量计板损坏(huai)。可(ke)更换流(liu)量计主板。