Four measurement parameters instrumentation control system failure analysis step

Posted by igeelee on May 8th, 2019

1. Temperature control instrumentation system fault analysis steps

When analyzing the temperature control instrumentation system failure, we must first pay attention to two points: the system instrument adopts electric instrumentation measurement, indication and control; the measurement of the instrumentation of the system often lags behind.hose crimping tool.

(1) The indication value of the temperature meter system suddenly changes to the maximum or minimum, which is generally the fault of the instrument system. Because the temperature meter system measures a large lag, no sudden changes will occur. The cause of the fault at this time is mostly caused by thermocouple, thermal resistance, compensation wire breakage or transmitter amplifier failure.

(2) Temperature control The instrumentation system indicates that there is a rapid oscillation phenomenon, which is mostly caused by improper adjustment of the control parameter PID.

(3) The temperature control instrument system indicates that there is a large and slow fluctuation, which is probably caused by a change in the process operation. If there is no change in the process operation at the time, it is likely to be a malfunction of the instrumentation control system itself.

(4) Failure analysis step of the temperature control system itself: check whether the input signal of the regulating valve changes, the input signal does not change, the regulating valve acts, the diaphragm of the diaphragm head is leaked; whether the input signal of the regulating valve positioner changes, the input signal No change, the output signal changes, the positioner is faulty; check the positioner input signal changes, then check the regulator output for change, if the regulator input does not change, the output changes, this is the regulator itself failure.

2. Pressure control instrument system failure analysis steps

(1) Pressure control system When the instrument indicates that there is rapid oscillation fluctuation, first check whether the process operation has changed. This change is mostly caused by poor process setting and PID parameter tuning of the regulator.

(2) Pressure control system Instrumentation indicates that there is a dead line, the process operation changes the pressure indication or does not change, the general fault occurs in the pressure measurement system, first check whether the measurement of the pressure guiding conduit system is blocked, not blocked, check the pressure There is no change in the transmitter output system, there is a change, and the fault is in the controller measurement indication system.