The failure and treatment of transmitter

Failure and maintenance of pressure transmitters

In the process of power plant operation, the application of transmitters is very extensive and very common, but sometimes various faults may occur. If the faults cannot be eliminated in time, it will seriously affect the safe and economic operation of the unit. Let's talk about the failure and maintenance of pressure transmitters based on our own practical experience.

Transmitters are roughly divided into pressure transmitters and differential pressure transmitters. Transmitters are commonly used to measure pressure, differential pressure, vacuum, liquid level, flow, and density. Transmitters are divided into two-wire and four-wire systems, especially two-wire transmitters; there are smart and non-intelligent, smart transmitters are gradually increasing; there are pneumatic and electric points, and electric transmitters are mostly ; In addition, there are intrinsically safe and flameproof types according to the application; the main types of transmitters according to the application conditions are as follows: low (micro) pressure / low differential pressure transmitter; medium pressure / medium differential pressure transmission Transmitter; high pressure / high differential pressure transmitter; absolute pressure / vacuum / negative pressure differential pressure transmitter; high temperature / pressure, differential pressure transmitter; corrosion resistance / pressure, differential pressure transmitter; easy to crystallize / pressure, Differential pressure transmitter. In the process of power plant operation, the application of transmitters is very extensive and very common, but sometimes various faults may occur. 

If the faults cannot be eliminated in time, it will seriously affect the safe and economic operation of the unit. Let's talk about the failure and maintenance of pressure transmitters based on our own practical experience. The sensitive parts of the capacitive pressure transmitter measuring part adopt fully welded structure, and the electronic circuit part adopts wave soldering and connector installation. The overall structure is firm, durable, and has few failures. For the vast majority of users, if a sensitive component is found to be faulty and cannot be repaired by itself, it should contact the manufacturer to replace its integral component.

Inspection of the measuring part of the yokogawa pressure transmitter

Faults in the measurement part of the transmitter will cause the transmitter to have no output or abnormal output. Therefore, the measurement sensitive parts of the transmitter should be checked first. a. Remove the flange to check whether the sensitive part isolation diaphragm is deformed, damaged or oil leakage occurs. b. Remove the compensation board without taking out the sensitive parts. Check that the insulation resistance of the housing should not be less than 100MΩ when the voltage does not exceed 100V. c. Connect the circuit and the air circuit. When the pressure signal is at the upper limit of the range, turn off the air source. The output voltage and reading value should be stable. If the output voltage drops, it means that the transmitter is leaking. You can use soapy water to check the leak.

Inspection of the absolute pressure transmitter circuit

After switching on the power supply, after a given input pressure signal, check the output voltage of the transmitter

The state of the signal. If there is no output voltage, first check whether the power supply voltage is normal and meets the power supply requirements for wiring errors between the power supply, the transmitter and the load equipment. If there is no voltage on the transmitter wiring terminal or the polarity is reversed, it can cause the transmitter to have no voltage signal output. To eliminate the above reasons, you should further check whether the components in the amplifier board circuit are damaged or not. The circuit board connectors have poor contact. You can compare the measured voltage of the normal instrument with the measured voltage corresponding to the faulty instrument to determine the necessary situation of the fault point. A faulty amplifier board can be replaced by the following. Special attention should be paid to anti-static measures for the J-type amplifier board when inspecting the flow-type transmitter.