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过程控制计算机用于过程控制已日趋广泛,但是对于许多使用气动仪表控制的工厂怎么办?是一个值得探讨的问题。自从过程工业使用计算机后产生了两种误解,其一认为现有气动仪表已无用;其二认为气动仪表与电子计算机的连接非常麻烦。在这两种误解的影响下,国内有些单位在应用计算机时,将气动仪表全部拆除,装上电动变送器,将过程参数送入计算机。有些新建的工厂,为了考虑今后使用计算机,也就尽量不采用气动仪表。那些拆掉气动仪表使用计算机的工厂,一俟发现计算机的可靠性远远不如模拟仪表,于是又装上许多电动仪表作后备,这样一拆一装,不仅投资甚巨,而且也使控制系统复杂化了,操作也极为不方便。图一为使用气动仪表的控制系统图,图二为使用计算机后,采用电动仪表作后备的控制
Process control computers have become more widely used for process control, but for many factories that use pneumatic instrument control, it is a question worth considering. Two misunderstandings have emerged since the process industry was using the computers, one of which considered the existing pneumatic instruments useless and the second that the connection of the pneumatic instruments to the computers was cumbersome. Under the influence of these two kinds of misunderstandings, some domestic units in the application of computers, the pneumatic instruments are all removed, fitted with electric transmitter, the process parameters into the computer. Some new factories, in order to consider the future use of computers, it will try not to use pneumatic instruments. Those factories that use pneumatic instruments to dismantle their computers, once found that computers are far less reliable than analog instruments, have installed a large number of electric instruments as backups. This disassembly not only made great investments, but also complicated the control system The operation is also very inconvenient. Figure 1 is the use of pneumatic instrumentation control system diagram, Figure II is the use of computers, the use of electric instruments for backup control