Common Faults and Solutions of PT Pressure Transmitter

PT pressure transmitters are mainly used for measuring and controlling pressure parameters in industrial processes. They are widely applied in industries such as petroleum, chemical processing, and power generation. There are many types of pressure transmitters, which can be classified in different ways according to their operating principles and applications.

Pressure transmitters are primarily used for remote pressure indication and control. They often operate in harsh environments such as high temperatures, low-pressure conditions, corrosive media, and vibration, where the likelihood of failure is relatively high. Therefore, studying the influencing factors and common faults of pressure transmitters is of great practical significance.

Several Common Types of PT Pressure Transmitter Faults

1. Wiring Faults

When a wiring fault occurs, the computer display may show abnormal readings. Open the transmitter junction box and check for loose connections, short circuits, or open circuits. Troubleshooting can be performed by checking the power supply, testing insulation resistance, and measuring circuit resistance.

2. Variable Frequency Interference

During cable routing, different signal lines may interfere with one another. Interference is especially severe when power cables and signal cables are routed through the same conduit. This can result in communication failure or incorrect transmitter readings. Such problems can be avoided by increasing the separation distance between instrument cables and power cable trays.

3. Impulse Line Faults

Common impulse line faults include blockage, air leakage, and liquid accumulation. Blockage is usually caused by untimely purging or by dirty or viscous media. Air leakage occurs because transmitters are connected with multiple accessories such as electrical fittings and shut-off valves, which increase potential leakage points. Liquid accumulation is typically caused by improper gas pressure tapping methods or incorrect impulse line installation, and it can affect measurement accuracy.

4. Electrical Signal Transmission Faults

Improper use or maintenance of PT pressure transmitters can easily lead to electrical signal transmission problems. For example, to save time, a transmitter may be installed too close to the measured equipment, resulting in an excessively long signal transmission distance. This can cause signal interference or attenuation. In such cases, the cable cross-sectional area should be increased as required.

PT Pressure Transmitter Troubleshooting

1. Output Signal is Zero

When a PT pressure transmitter indicates zero pressure, the following steps should be taken. First, check whether there is actual pressure in the pipeline and whether the instrument power supply is functioning properly. Next, verify that the power supply polarity is not reversed. Finally, inspect the electronic circuit board, sensing diaphragm, and the transmitter supply voltage.

2. No Response to Applied Pressure

If the transmitter shows no response when pressure is applied, check whether the valves in the impulse line are operating properly, whether the transmitter protection jumper settings are correct, and whether the impulse line is blocked. Also verify the transmitter zero and span settings, and replace the sensing diaphragm if necessary.

3. Pressure Reading Deviation

If the pressure reading is obviously too high or too low, first check the impulse line for leakage. Then inspect the valves on the impulse line and fine-tune the sensor calibration. If the issue persists, replace the sensing diaphragm.

4. Unstable Pressure Readings

This problem can be diagnosed by isolating external sources of interference, checking the impulse line for leaks, inspecting the pipeline for debris or blockages, examining whether the isolation diaphragm is corroded or deformed, and checking the sensing diaphragm.

After understanding the common fault types of PT pressure transmitters and their corresponding troubleshooting methods, users should take appropriate measures based on actual operating conditions to diagnose and resolve issues. At the same time, strengthening routine maintenance and preventive measures is an effective way to reduce the likelihood of failures.