Publish Time: 2022-01-21 Origin: Site
After switching on the power supply, if the output of the pressure transmitter is too high and greater than 10VDC or the output is too low and less than 2.0VDC after a given input pressure signal, and the input pressure signal is changed and the zero point and span screws are adjusted, the output will have no response. For this type of failure, in addition to checking whether the sensitive parts of the transmitter measuring part are abnormal, check whether the "oscillation control circuit part" on the transmitter amplifier board is working properly. The normal peak voltage between high frequency transformer T1-12 should be 25~35VP-P and the frequency is about 32kHz. Secondly, check the working condition of each operational amplifier on the amplifier board and whether the components of each part are damaged or not. Such failures require replacement of the amplifier board.
The transmitter has very strict requirements on circuit design and process assembly quality. In actual use, it is very good to contact the manufacturer to replace its faulty circuit board after checking and confirming the circuit failure to ensure the stability and long-term operation of the instrument.
Most of the faults on the construction site are caused by improper use and installation methods, which can be summarized in several aspects.
1. The orifice plate of the primary component, the remote measuring joint, etc. are blocked or the installation form is not correct for the pressure point.
2. Leakage or blockage of the pressure pipe. There is residual gas in the filling pipe or residual liquid in the filling pipe. The transmitter deposits deposits in the process flange to form a measurement dead zone.
3. The transmitter wiring is incorrect. The power supply voltage is too high or too low.
Poor contact at the wire terminal connection.
4. The installation method is not strictly in accordance with the technical requirements and the on-site environment does not meet the technical requirements. The above failures will cause the transmitter to output abnormally or measure inaccurately, but after careful inspection, use and install in strict accordance with the technical requirements and take effective measures in time. The problem can be eliminated. The transmitter should be sent to the laboratory or The manufacturer conducts further inspections.
The following is an example of practical application: the design principle of the pressure transmitter wiring diagram: As the name suggests, the measured result of the pressure transmitter wiring diagram is the pressure difference, that is, △P=ρg△h. And because the oil tank is often cylindrical, the area S of the cross-section circle is constant, then the weight G=△P·S=ρg△h·S, S is constant, and G is proportional to △P. That is, as long as the △P value is accurately detected, which is inversely proportional to the height △h, when the temperature changes, although the oil volume expands or shrinks, and the actual liquid level increases or decreases, the detected pressure will always remain unchanged. If the user needs to display the actual liquid level, it can also be solved by introducing medium temperature compensation.