【 Weak current College 】 field instrumentation system common breakdown analysis step description---Power By 【 China power house network 】

At present, with petrochemicals, steel, paper, food, pharmaceutical enterprises increasing level of automation, field instrument maintenance personnel skills set higher requirements. To reduce the processing time of instrument failure, ensure safe production increase economic efficiency, and this article was published a little instrument field maintenance experience for instrument maintenance personnel. I. field instrument system basic analysis step field instrument measurement parameters generally consists of temperature, pressure, flow, level four parameters. Now under the measured parameters, to analyze different field instrument failure. 1. first, in the analysis of field instrument failure before, you want to compare a thorough understanding of the related instrument system of production process, production process and conditions, understand instrument design, design intent, instrument systems structure, characteristics, properties and parameter requirements. 2. in analysis check field instrument system malfunction prior to the on-site operation workers understand the production of load and raw materials of parameter changes, check the meter records curve for comprehensive analysis to determine why the instrument failure. 3. If the meter records curve as a dead-line (little change or a line called dead line), or record the curve for the original fluctuations, now suddenly turns into a straight line; failure is likely in instrument system. Because the current recording instruments mostly DCS computer system, a very high sensitivity, changes of parameters can be very sensitive response. At this point you can artificially change the technical parameters, see the curve changes. If you do not change the basic instrument system that is out of the question; if the normal variation, basic determines that no major instrument system. 4. change in technical parameters found record curves mutation or skip to the maximum or minimum, at this point of failure in instrumentation systems. 5. failure to appear before the performance curve for instrument has been recorded correctly, fluctuate after record curves become law or make the system difficult to control, even the manual operation or control, in which failure could be caused by the operating system process. 6. when discovered DCS display instrument is not working properly, you have to check the same intuitive instrument indicates that the value, if they differ, it may well be the instrument of a system failure. In conclusion, the analysis of field instrument failure, to pay particular attention to be logging control object and the properties of the valve, which can be field instrument system of the failure. Therefore, we have from the field instrument system and process of the operating system two aspects into consideration, analysis, check carefully. Second, the four measurement parameters gauge control system failure analysis steps 1. temperature control instrument system failure analysis step analysis of temperature control instrument system failure, the first thing to note two things: the system instrument use electric instrumentation, direction and control; the system of measurement instrumentation is often lagging behind. (1) temperature meter system indicates that the value suddenly to the maximum or minimum, General instrument system failure. Because the temperature meter system measuring latency is large, the change does not happen suddenly. At this point of the fault reason mainly thermocouple, RTD, compensation wire breakage or malfunction resulting transmitter amplifier. (2) temperature control instrument system indicates a rapid Oscillation phenomenon, much as the PID control parameters caused by improper adjustments. (3) the temperature control instrument system indicates that there have been sharp fluctuations of slow, it may be due to changes in process operations, such as the process operation did not change, it may well be instrument control system itself. (4) temperature control system itself of fault analysis step: check whether the input signal control valve, the input signal does not change, the control valve movement, the diaphragm membrane head valve leak; check valve positioner input signal is changed, the input signal does not change, the output signal changes, Locator failed; check for a change of input signal Locator, then check the regulator output has not changed, if you enter does not change, the regulator output changes, this is the fault of the regulator itself.