Pressure transmitter installation requirements

Before installing and using the pressure transmitter, you should read the product sample and instruction manual carefully. The pressure interface must not be leaked during the installation to ensure that the range and wiring are correct. The shell of pressure sensor and transmitter is generally required to be grounded. Signal cable should not be mixed with power cable. Strong electromagnetic interference should be avoided around sensors and transmitters. Sensors and transmitters should be cycled according to industry regulations during use.

Capacitive Pressure Transmitter Common Fault Analysis and Processing Methods Capacitive pressure transmitter measures all sensitive parts in all-welded structure. The electronic circuit part adopts wave soldering and connector installation. The overall structure is sturdy and durable, with few failures. . For the vast majority of users, if it is found that a sensitive part is malfunctioning, it cannot generally be repaired on its own. Contact the manufacturer to replace its entire parts.

Transmitter measurement section Checking the failure of the transmitter measurement section will cause the transmitter to have no output or an abnormal output. Therefore, first check the transmitter's measurement-sensitive parts. Remove the flange and inspect the isolation diaphragm of sensitive parts for deformation, breakage and oil leakage. Remove the compensation plate, do not take out sensitive parts, check the insulation resistance of the plug-in case, the insulation resistance should not be less than 100MΩ in the case of voltage not exceeding 100V. Turn on the circuit and gas circuit. When the pressure signal is the upper limit of the range, turn off the gas source, and the output voltage and reading value should be stable. If the output voltage drops, the transmitter is leaking and you can use soapy water to check for leaks.

Check the transmitter circuit section for power supply. After the input pressure signal is given, check the status of the voltage signal at the output of the transmitter. If there is no output voltage, first check whether the power supply voltage is normal; whether it meets the power supply requirements; whether there is any wiring error between the power supply and the transmitter and the load device. No voltage or reversed polarity on the transmitter terminals can cause the transmitter to output no voltage signal. Exclude the above reasons, you should further check the amplifier board circuit components for damage problems; circuit board connectors have no contact with the phenomenon of bad, you can use the measured voltage of the normal instrument and the failure meter corresponding to the measured voltage compared to the method to determine the failure Point, if necessary, replace the faulty amplifier board. When checking flow-type transmitters, special attention should be paid to J-type amplifier boards to prevent static electricity.

After power on, if the transmitter output is too high (greater than 10 VDC) or the output is too low (less than 2.0 VDC) after the input pressure signal is given, the output will not respond when the input pressure signal is changed and the zero point is adjusted and the range screw is turned on. . For this kind of fault, in addition to checking whether there are any abnormalities in the sensitive parts of the transmitter's measurement part, check whether the “oscillation control circuit part” on the transmitter's amplifier board is working properly or not. The normal peak voltage between high-frequency transformer T1-12 should be 25~35VP-P; the frequency is about 32kHz. Secondly, check the operational status of each operational amplifier on the amplifier board; whether the components of each part are damaged or not. This type of fault requires the replacement of the amplifier board. Transmitter in the circuit design and process assembly quality requirements are very strict, in actual use of the line fault, after inspection and confirmation, it is best to contact the manufacturer to replace the fault circuit board to ensure the stability of the instrument long-term work And reliability.

On-site failures The majority of failures that occurred on construction sites due to improper use and installation of pressure sensors were summarized in several aspects.

1. The primary component (orifice plate, remote measurement connector, etc.) is blocked or improperly installed, and the pressure point is unreasonable.

2. Leakage or blockage of the pressure tube, residual gas in the fluid filled tube or residual fluid in the aeration tube, deposits in the process flange of the transmitter, forming a dead zone for measurement.

3. The transmitter is wired incorrectly and the power supply voltage is too high or too low, indicating poor contact between the meter header and the meter terminal block connections.

4. The installation was not strictly in accordance with the technical requirements. The installation method and the site environment did not meet the technical requirements.

The above pressure sensor and transmitter failure will cause the transmitter output is not normal or measurement is not accurate, but after careful inspection, in strict accordance with the technical requirements of use and installation, take effective measures in time, the problem can be ruled out, can not be handled In case of failure, the transmitter should be sent to the laboratory or manufacturer for further inspection.