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一、前言在矿山、化工、石油,电力和冶金等工业部门的自动化领域中广泛采用了各种规格的温度变送器。目前国内使用的大都是DDZ—Ⅱ系列电动单元组合仪表DBW 型温度变送器,主要采用的是分立元器件,因此电路稳定性差,而且功率大,不防爆;体积也较大,不符合煤矿,石油等能源部门使用。而且其输出电流为0—10mA,在检测中也不能正确区分是线路故障还是起点电流,因而很不便。为了克服上述缺点,目前一些自动化仪表厂从国外购买了新的变送器,由于使
I. Preface A wide range of temperature transmitters are widely used in automation of mining, chemical, petroleum, power and metallurgical industries. At present, most domestic use DDZ-Ⅱ series electric unit combination instrument DBW temperature transmitter, the main use of discrete components, so the circuit stability is poor, and the power is large, not explosion-proof; the volume is larger, does not meet the coal, Oil and other energy sectors. And its output current is 0-10mA, in the test can not correctly distinguish between the line fault or starting current, which is very inconvenient. In order to overcome the above shortcomings, some automated instrument factory purchased a new transmitter from abroad, due to