How to diagnose the pressure transmitter when it encounters a problem: If the pressure goes up, the transmitter output does not go this way, you should first check whether the pressure interface is leaking or blocked. If it is not confirmed, check the wiring method, if the wiring is correct, then Check the power supply. If the power supply is normal, check whether the sensor has an output at the zero position, or simply pressurize to see if the output changes. If there is a change, the sensor is not damaged. Other reasons for this may be instrument damage, or problems in other parts of the entire system. The output of the pressure transmitter does not change, the output of the pressure transmitter changes suddenly, and the pressure relief transmitter cannot return to zero. The cause of this phenomenon is most likely caused by the pressure sensor seal ring, usually because of the seal ring specifications (too soft or too thick). When the sensor is tightened, the seal ring is compressed into the sensor pressure port to block the sensor and pressurize it. When the pressure medium cannot enter, but when the pressure is very high, the seal ring is suddenly opened, the pressure sensor changes under pressure, and when the pressure decreases again, the seal ring returns to block the pressure inlet, and the remaining pressure cannot be released, so The zero position of the sensor cannot be lowered again. The best way to eliminate this is to remove the sensor and directly check whether the zero position is normal. If the seal is replaced normally, try again.
There are several reasons for the unstable output signal of the transmitter :
A. The pressure source itself is an unstable pressure
B. Does the meter or pressure sensor have a strong anti-interference ability?
C. Insufficient sensor wiring
D. The sensor itself vibrates a lot
E. Sensor failure Possible reasons for the transmitter to fail to output when connected to power are:
F. Incorrect wiring (check the instrument and sensor)
G. Open or shorted wires
H. No power output or power mismatch
I. Instrument is damaged or mismatched
J. Sensor damage The deviation between the transmitter and the pointer pressure gauge is large
First, deviations are normal. Second, confirm the normal deviation range
Method of confirming the normal error range: Calculate the error value of the pressure gauge. For example: the pressure gauge has a range of 30bar, an accuracy of 1.5%, and the minimum scale is 0.2bar. The normal error is: 30bar * 1.5% + 0.2 * 0.5 (visual error) = 0 . 55bar pressure transmitter error value. For example: the pressure sensor range is 20 bar, the accuracy is 0.5%, and the instrument accuracy is 0.2%. The normal error is: 20 bar * 0.5% + 20bar * 0.2% = 0.18bar
The possibility error range that appears in the overall comparison should be based on the error range of the device with large error value. In the above example, the deviation between the sensor and the transmitter can be regarded as normal within 0.55bar. If the deviation is very large, use a high-precision meter (at least this meter is higher than the pressure gauge and sensor) for reference. Influence of the installation position of the micro differential pressure transmitter on the zero output Because the measuring range of the micro differential pressure transmitter is very small, the weight of the sensing element in the transmitter will affect the output of the micro differential pressure transmitter, so It is normal for the zero position of the differential pressure transmitter to be installed. During installation, the pressure-sensitive part of the transmitter should be perpendicular to the direction of gravity. If the installation conditions are limited, the transmitter should be adjusted to zero to a standard value after installation.