The electrode liquid connection resistor of the target flowmeter manufacturer shall be measured immediately after the instrument panel is just installed and adjusted, and recorded. In the future, every maintenance will be measured once, and the analysis and analogy of such data information will help to identify the causes of the instrument cluster problems.

The contact resistance between the electrode and the liquid lies in the conductivity of the liquid to be measured on the contact surface. There are clear differences in the measured resistance values of contradictory substances. The electrode liquid connecting resistor can identify and measure the resistor between each electrode terminal and the ground when measuring the liquid contained in the tube with the pointer type digital multimeter. The difference of touch resistance between two electrodes should be less than 10% - 20%, otherwise the mark is faulty.

If there is any difference between the measured electrode wetted resistor and the original measured value, the reasons are: a. the covering of the two electrode dielectric strength adhesive layer is different or the insulation resistance of a certain electrode signal control circuit is reduced; B. when the resistance value is added, the electrode surface is covered by the cable sheath; C. when the resistance value is reduced, the conductive stacking layer or the electrode assembly line (such as the insulating layer sheath) is adhered to the adjacent inner lining surface of the electrode Coil) insulation reduced. Sometimes it does not constitute a problem, but it should be accepted as a precursor to the problem.

(4) Measure the working voltage of electrode / liquid inter electrode

(5) Reflecting on the insulation of signal circuit and the middle insulation layer of excitation circuit / signal power supply circuit, measuring the working voltage will be helpful to distinguish whether the electrode can be polluted or covered, so as to form the problem of unstable zero point or output shaking.

The overall goal of this reflection is to comment on whether intrusion can be introduced due to the reduction of insulation. The working principle of the target flowmeter is to reflect on the signal power supply circuit, the signal line and the electrode should be temporarily loosened. The reasons for the decrease of the insulation layer are that the terminal is not sealed into the moisture, the cable of the safety protection controller is cut off and then continues without proper waterproof treatment, etc.

(6) Introspection of electrode insulation resistance and lining condition

Generally, the electrode insulation resistance is more than 100m Ω, and the reduction of the insulation layer of the target flowmeter is mainly caused by the electrode and shaft sleeve being soaked outside and damp back (it is OK to use a heat blower to clean the moisture); if the insulation layer is damaged (such as the corrosion liquid invading from the sealing part), the controller shall be exchanged or returned to the manufacturer for repair. This introspection requires that the instrument panel of caliber should be removed from the pipeline, and the large-diameter instrument panel should be emptied of its own liquid and then put into the pipeline from the inlet hole for inspection: wipe the inner surface of the inner lining and use a megger to identify and detect the insulation resistance of two electrodes to the ground; if there is an adhesive layer in the inner lining, the flow poison should be removed and the cleaning cycle time should be determined according to the thickness of the layer; if the adhesive layer is not enough and the conductivity is the same as that of the liquid, it can be careless If the conductivity of the adhesive layer is lower than that of the liquid, there will be additional deviation in the forward direction, on the contrary, there will be additional deviation in the negative direction.

For the reflection pressure transmitter, in addition to zero point reflection, the air flow meter, converter and butt cable are also separated.

1. Zero reflection of the whole equipment

The professional skills of zero reflection of the whole equipment are as follows: the measuring pipe of air flow meter contains liquid and has no theme activity. Many companies do not have preconditions on the spot and leave the zero reflection and regulation of the whole equipment, but they can then make zero reflection and regulation of the converter by themselves. In terms of professional skills, it is necessary to measure the electrode liquid resistance of the air flow meter immediately after the completion of the controller's introspection and on the premise that the insulation resistance of the excitation regulator control circuit and the signal control circuit of the maintenance port controller is all normal (including the cable), and record it. In the future, every maintenance will be measured once, and the analysis and analogy of such data information will help to identify the causes of the instrument cluster problems.

The contact resistance between the electrode and the liquid lies in the conductivity of the liquid to be measured on the contact surface. There are clear differences in the measured resistance values of contradictory substances. The electrode liquid connecting resistor can identify and measure the resistor between each electrode terminal and the ground when measuring the liquid contained in the tube with the pointer type digital multimeter. The difference between the touch resistance of two electrodes should be less than 10% - 20%, otherwise the mark is faulty.

If there is any difference between the measured electrode wetted resistor and the original measured value, the reasons are: a. the covering of the two electrode dielectric strength adhesive layer is different or the insulation resistance of a certain electrode signal control circuit is reduced; B. when the resistance value is added, the electrode surface is covered by the cable sheath; C. when the resistance value is reduced, the conductive stacking layer or the electrode assembly line (such as the insulating layer sheath) is adhered to the adjacent inner lining surface of the electrode Coil) insulation reduced. Sometimes it does not constitute a problem, but it should be accepted as a precursor to the problem.

(4) Measure the working voltage of electrode / liquid inter electrode

Measuring the working voltage will help to distinguish whether the electrode is dirty or covered, so as to form the problem of unstable zero point or output shaking.

(5) Reflection on the insulation of signal circuit and excitation circuit / intermediate insulation of signal power circuit

The overall goal of this reflection is to comment on whether intrusion can be introduced due to the reduction of insulation. When reviewing the signal power circuit, the signal wire and electrode should be temporarily loosened. The reasons for the decrease of the insulation layer are that the terminal is not sealed into the moisture, the cable of the safety protection controller is cut off and then continues without proper waterproof treatment, etc.

(6) Introspection of electrode insulation resistance and lining condition

This introspection requires that the instrument panel of caliber should be removed from the pipeline, and the large-diameter instrument panel should be emptied of its own liquid and then put into the pipeline from the inlet hole for inspection: wipe the inner surface of the inner lining and use a megameter to identify and detect the insulation resistance of two electrodes to the ground; if there is an adhesive layer in the inner lining, it is necessary to eliminate the liquid poison and make it thin and thick according to the layer thickness