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a. Transmitter output ≥ 20mA. 1. Is the transmitter’s power supply functioning properly? Solution: If the voltage is less than 12VDC, check whether there is a heavy load in the circuit; the input impedance of the transmitter’s load should satisfy RL ≤ (Transmitter supply voltage – 12V) / (0.02A) Ω. 2. Is the actual pressure higher than the range specified for the smart pressure transmitter?； Solution: Select a smart pressure transmitter with an appropriate range. 3. Is the pressure sensor damaged? Severe overloading can sometimes damage the diaphragm. Solution: It needs to be sent back to the manufacturer for repair. 4. Are the connections loose? ； Solution: Connect the wires properly and tighten them. 5. Is the power cable connected correctly? Solution ； The power cable should be connected to the corresponding terminal. b. The transmitter output is ≤4mA. 1. Check whether the transmitter’s power supply is functioning properly. Solution: If the voltage is less than 12VDC, it is necessary to check for any heavy loads in the circuit; the input impedance of the transmitter’s load should satisfy the condition RL≤(Transmitter supply voltage – 12V)/(0.02A) Ω. 2. Determine whether the actual pressure exceeds the range specified for the smart pressure transmitter ； Solution: Select a smart pressure transmitter with an appropriate range. Check whether the pressure sensor is damaged; severe overloading can sometimes damage the diaphragm. Solution: It needs to be sent back to the manufacturer for repair. c. No output from the transmitter: 1. Check whether the transmitter’s power supply is connected reversely ； Solution: Ensure the power polarity is correct. 2. Measure the supply voltage to the transmitter to check whether there is 24V DC voltage ； Solution: It is necessary to ensure that the power supply voltage to the transmitter is ≥12V (i.e., the voltage at the transmitter’s power input terminal is ≥12V). If there is no power supply, check whether the circuit is disconnected and whether the measuring instrument has been selected incorrectly (the input impedance should be ≤250Ω) ； Wait. 3. If it has a header, check whether the header is damaged (you can first short-circuit the two wires of the header; if it works normally after short-circuiting, then the header is damaged) ； Solution: If the header is damaged, it needs to be replaced. 4. Connect the ammeter in series with the 24V power circuit to check whether the current is normal ； Solution: If it is functioning normally, it indicates that the transmitter is working properly; in this case, check whether other instruments in the circuit are also functioning correctly. 5. Is the power supply connected to the transmitter’s power input terminal? ； Solution: Connect the power cord to the power terminals. d. Incorrect pressure indication 1. Is the power supply to the transmitter functioning properly? Solution: If the voltage is less than 12VDC, check whether there is a heavy load in the circuit; the input impedance of the transmitter’s load should satisfy RL≤(Transmitter supply voltage – 12V)/(0.02A) Ω. 2. Is the reference pressure value accurate? Solution: If the accuracy of the reference pressure gauge is low, replace it with a gauge that has higher accuracy. 3. Is the range of the pressure indicating instrument consistent with that of the smart pressure transmitter? Solution: The range of the pressure indicating instrument must be identical to that of the smart pressure transmitter. 4. Are the inputs of the pressure indicating instrument connected correctly? Solution: If the input for the pressure indicating instrument is 4–20mA, then the output signal from the transmitter can be connected directly ； If the input to the pressure indicator is 1–5V, a resistor with a precision of at least one thousandth and a resistance value of 250Ω must be connected in parallel at the input of the pressure indicator, before connecting it to the transmitter’s input. 5. The input impedance of the transmitter load should satisfy RL ≤ (transmitter supply voltage – 12V) / (0.02A) Ω. Solution: If this condition is not met, appropriate measures can be taken depending on the situation; for example, increasing the supply voltage (but it must remain below 36VDC) or reducing the load. 6. Is the input terminal open circuit when the multi-point paper recorder is not recording? ； Solution: If there is an open circuit, then: (1) no other loads can be connected ； (2) Switch to another recorder for which the input impedance is ≤250Ω when no record is available. 7. Is the equipment enclosure grounded? Solution: Ground the equipment enclosure. 8. Is the wiring separated from that of the AC power supply and other power sources? Solution: Separate the wiring from that of the AC power supply and other power sources. 9. Is the pressure sensor damaged? Severe overloading can sometimes damage the diaphragm. Solution: It needs to be sent back to the manufacturer for repair. 10. Check whether there is sand, impurities, or other substances blocking the pipes; the presence of such impurities can affect the accuracy of measurements. Solution: Remove the impurities and install a filter screen before the pressure connection. 11. Is the temperature of the pipeline too high? The operating temperature range for pressure sensors is -25~85°C, but it is advisable to keep the temperature within -20~70°C in practice. Solution: Use a buffer tube to dissipate heat; it is best to fill the buffer tube with cold water before use, so as to prevent overheated steam from directly impacting the sensor and thus damaging it or reducing its service life.