Pressure transmitter is the most commonly used in modern industrial control equipment, whether the normal work of the normal impact of industrial production. However, whether it is domestic transmitter or imported transmitter, in the course of the use will inevitably have some failures occur, the working environment, improper operation or the transmitter itself will be a variety of failures. Therefore, it is necessary to understand the common faults and routine maintenance methods of pressure transmitters! Today, the instrument control Jun for everyone to organize some of the common transmitter failure, solutions, routine maintenance and precautions, together to find out about it.
Pressure transmitter in the course of the inevitable use of a variety of failures, the impact of many factors, such as: pressure transmitter and the original sensor between the gap between the filling fluid leakage, zero and range offset, the output is not Stability, etc. will lead to pressure transmitter damage or even damage; weather factors will also affect the transmitter, such as: lightning will damage the transmitter box circuit, resulting in communication; wet environment will damage the line; change Unwatchable range selection will cause irreversible distortion of the sensing element.
Here are some common types of faults:
When the line fault occurs, the computer displays the value of the abnormal, the transmitter junction box to open, check the line there is a virtual connection, short circuit or disconnected phenomenon, in the use of measuring power, shaking insulation and resistance methods such as troubleshooting.
2. Frequency conversion interference
In the case of wiring, a variety of signal lines interfere with each other, especially in the power line and signal line string in the same pipeline generated interference is more serious, in which case will lead to the transmitter does not communicate or even cause errors. This can be avoided by increasing the distance between the meter cable and the power cable slot.
3. Pressure pipe failure
Pressure tube failure is usually a plugging tube, pressure tube leakage, pressure tube effusion three types of failure, pressure plug is generally caused by the discharge is not timely or dirty media, sticky lead; Is caused by the transmitter power, cut-off valve and other accessories more, an increase of leakage points; pressure tube effusion is usually due to unreasonable gas pressure or pressure pipe installation error caused by the pressure tube will affect the effusion measurement accuracy.
4. Electrical transmission failure
If the pressure transmitter is improperly used or maintained, it is easy to cause the transmission of the electrical signal. For example, in order to save time on the transmitter near the device under test, resulting in signal transmission distance is too far, the signal will appear interference or attenuation phenomenon, this time according to the need to increase the cable cross-sectional area.
Daily and regular maintenance:
1. Tour check
Check the instrument instructions, with or without abnormal, to see if he fluctuates within the specified range; some transmitters do not have field instructions, go to the control room to see its second indication. Whether there is a debris around the instrument or whether the instrument surface dust, should be promptly cleaned and cleaned. Instrumentation and process interface, pressure pipe and the valve between the leakage, corrosion and so on.
2. Periodic inspection
For some do not need to check the instrument every day, to check the time interval. Regular zero check, because the transmitter has a secondary valve or three valve group, five valve group, so zero check is very convenient, do not need too much time. However, the transmitter used in the control system, no matter how short the inspection time, still need to automatically change to manual control, so this instrument can be longer than the zero cycle. Since these inspections require the removal of street inspection equipment, it is cumbersome, so if there is no abnormality, the inspection cycle can be appropriately longer.
Regularly discharge, drain and vent.
Regularly on the easy to block the media pressure tube to purge, irrigation and other liquid.
Regularly check the transmitter parts integrity, no serious corrosion, damage; nameplate, logo clear and correct; fasteners shall not loose, good contact with the connector, the terminal wiring firm.
Regular field measurement lines, including the input and output circuits are intact, whether the line disconnected, short circuit, insulation is reliable and so on.
When the transmitter is running, its housing must be well grounded. The transmitter used to protect the system should have measures to prevent power, short circuit, or output open circuit.
In the winter season should check the instrument to take the source line heat tracing, so as not to take the source line or transmitter measurement components are frozen damage.