1. No total flow output

2. The data signal becomes smaller and smaller or suddenly decreases. Check whether the insulating layer between the two electrical stages is damaged or short circuited. The resistance between the two electrical stages of the plug-in ultrasonic flowmeter is normal in the middle of (70-100) Ω; the inner cavity of the measuring pipe will be stained, and the electrical stage shall be cleaned and scrubbed to avoid scratching the lining. Check whether the inner lining of the measuring pipe is damaged. If it is damaged, it should be replaced. Check if there is any fault in one part of the switching power supply, check if the power supply voltage is normal; check if the fuse is connected; check if the arrow symbol of the controller is consistent with the inflow of fluid mechanics, if not, replace the installation position of the controller; check if the controller is filled with fluid mechanics, if not, dismantle and replace the pipeline or install vertically.

3. If the zero point is not stable, check whether the substance is filled with the measuring tube and whether there are bubbles in the substance. If there are bubbles, the degasser can be modified upstream and downstream. If the level installation can be changed to vertical installation. Check whether the instrument grounding device is intact. If it is not good, carry out three-level grounding device (grounding resistance ≤ 100 Ω). Check whether the conductivity of the substance is not less than 5 μ s / cm. Check the substance If it is deposited in the measuring pipe, pay attention not to scratch the lining when eliminating it.

4. The marked value of total flow does not conform to the specific value. Check whether the hydrodynamics in the controller fills the pipe and whether there are bubbles. If there are bubbles, the degasser can be modified upstream and downstream. Check whether the grounding devices are in good condition. Check whether there are valves upstream and downstream of the steam flowmeter. If there are any, move them to the middle and downstream or make them fully open. Check whether the measurement range of the converter is set properly. If not, set the appropriate measurement range again.

5. The range fluctuates in a certain section. Check whether there is any change in the natural environment standard, such as new interference signal and other magnetic source or vibration endangering the normal operation of the instrument, immediately eliminate the influence or move the steam flowmeter; check and test the communication cable, and use the insulating tape to carry out the top solution, so that the transmission line, the inner shield, the outer shield and the middle of the cover do not touch each other.

The hydrodynamics of measuring the total flow with electromagnetic flowmeter must be conductive. Therefore, the manufacturer of flowmeter cannot use electromagnetic flowmeter to measure the total flow with non-conductive chemical substances such as steam, steam, raw oil and copper.

Operational failure

1. The common reasons for the failure of the inner cavity adhesion layer after the initial adjustment and normal operation for a period of time are: the inner cavity adhesion layer of the air flow meter, lightning strike, and the change of the natural environment standard.

2. Because electromagnetic flowmeter has more opportunities to measure floating solid or dirty body than other total flowmeter, the failure probability caused by inner cavity adhesion layer is relatively high. If the conductivity of the adhesion layer is similar to that of the liquid, the instrument can output all normal data signals, only changing the total flow area of the V-cone Flowmeter, resulting in potential fault of measurement deviation; if the adhesion layer is high conductivity, the electric potential between stages will be short circuited; if the dielectric strength adhesion layer, the electric surface layer will be insulated and the measuring power circuit will be cut off. The latter two conditions will make the instrument unable to work.

When lightning strikes the line, the magnetic induction instantaneous high voltage and surge current will destroy the instrument as soon as it enters the instrument. There are three ways to import lightning strike instrument: power plug, total flow power line between converter and excitation current line. It is not surprising that the analysis of the parts damaged in the lightning fault causes that the magnetic induction high voltage and surge current are mostly imported from the switch power line in the main control room, and the other two methods are less. It is also learned from the occurrence of major lightning accidents that not only the electromagnetic flowmeter fails, but also other instruments in the main control room often suffer from lightning accidents. Therefore, the application enterprise should understand the necessity of setting the lightning protection equipment of the instrument power plug in the main control room.

3. Transformation of natural environment standards

The key reason is the same as above in the aspect of fault natural environment during the regulation period, only the interference signal does not appear in the regulation period, but intervenes again during the operation period. For example, for an electromagnetic flowmeter whose protective grounding is not ideal, because there is no plant disturbance source during the regulation period, the operation of the instrument is normal. However, during the operation period, there are new interference signals (such as the pipeline around the measuring point or the pipeline arc welding performed remotely) that affect the normal operation of the instrument, and the output data signal fluctuates greatly.