Third quarter no flow signal output check and take measures, the cause of the problem without traffic signal output in general can be summarized as five aspects of the cause of the problem, they are (
The power not tong power aspects, such as fault;
Connect cable (
Excitation circuit, signal circuit)
Liquid flow status of the fault;
Sensor components damaged or measuring wall adhesion layer cause the failure of;
Converter fault components damage.
Second, check the program shown in figure 2 foot check electromagnetic flowmeter
no flow signal output of the process.
Press process fully consider first makes a preliminary research and judgment, and then detailed item by item check and test troubleshooting.
Check order successively listed process principles: (1) by observation or ask understanding shall not be obliged to large operations in the former, namely after the first difficult;
(2) the frequency on the same site maintenance experience and after-sales may appear higher probability;
(3) check itself has required the higher in the former.
If confirmed by the preliminary investigation is several fault reason, after a detailed check in advance.
1. Analog signal is sufficient to debug and check the electromagnetic flowmeter specially designed equipment, simulation of the flow sensor output signal, such as Shanghai guanghua instrument and meter plant LDZM type, Shanghai guanghua & middot;
Love is getting GS7, GS8 and GS9 type of instruments.
Figure 2 electromagnetic flowmeter no flow signal output check process three, fault inspection and take measures to this section discuss respectively 1: check of five aspects of the cause of the problem, the measures of 1, 1, check the power supply fault inspection flow chart 2 items.
* make sure has plugged into a power supply, check the power supply parts again.
Check the main power and excitation current fuse, if access to conform to the provisions of current value a new fuse again electrify and fuse, must find out the fault point.
Check the power supply circuit board output various voltage is normal, or try the replacement power circuit board.
2, check the connection cable system flow chart of fault check item 3.
Check respectively connected to the excitation system and signal system, whether or not it is connected correctly.
3, check the direction of liquid flow fluid and tube filled with sexual check the flow chart of 4, 5 items.
Liquid flow direction must be in accordance with the direction arrow on the sensor shell.
To be positive and negative to the measurement of the electromagnetic flowmeter, if the direction is not consistent, though still can be measured, but not yet show flow of positive and negative direction, must be correct.
If the sensor workload big, can also change the direction arrow on the sensor and reset display instrument symbols.
Pipe if not filled with liquid work in pipeline engineering design or sensor installation location wrong, make the sensor tube not filled with liquid.
Should take measures to avoid the installation as shown in figure 3 a, e and pipe emissions to the dotted line b location, converted to the c, d.
Figure 3 sensor installation position 4, integrity check sensor and measuring tube wall condition inspection flow chart 6, 7, 8, 9, 10 items.
Mainly check the terminal on the integrity and excitation coil, and measure the tube wall.
Excitation coil and the system fault often: (1) coil disconnection, (2) coil or its insulation terminal decline (3) the turn-to-turn short circuit.
Three kinds of fault in insulation reduction in frequency is relatively high.
Coil disconnection and insulation can easily multimeter and megohmmeter inspection.
Interturn short circuit inspection is relatively complicated, * first before new electromagnetic flowmeter with hui stearns electrode measuring the dc resistance and temperature measurement, and recorded as a reference value.
Check failure if a person of turn-to-turn short circuit, resistance is measured with a multimeter can be a judgment;
If a handful of turn-to-turn short circuit or to prove that no short circuit happens.
Must also use a bridge to measure and necessary copper resistance temperature coefficient of correction.
Sensor field coil circuit insulation down the cause of the relatively high failure frequency of the foot, electric IP65 protection grade (
Sensors are often flooded (short time
Such as sensors in a lower position around the accident of flooding)
, according to IP65 is dust-proof and water spray, only very easily immersed in water or moisture.
Even if is IP67 (
Dust-proof and short time immersed)
Or IP68 (
Dust-proof and progressive flooding)
Level, also occurs when the connection is completed, the introduction of cable seal or terminal lifted the lid sealing gasket does not meet the sealing requirements and form the accident.
Due to careless operation seal cushion part failure caused by feet are common.
Terminal blocks the insulation of the decline of be affected with damp be affected with damp, generally, the hot blow blow drying, can be used to restore insulation.
Coil sensor for two and a half fold protection shell of be affected with damp be affected with damp, can remove the shell cover in the oven, with appropriate temperature of drying.
For airtight type (
The welding structure of the enclosure)
Although the structure of magnetic sensor on guarantee will not be affected with damp be affected with damp, but also has a cable from the chariot and sealant interface into the case.
Sounding pipe wall condition attached insulation or conductive layer of reliable inspection determine foot sensor offline direct observation, but larger workload.
Can also use online indirect inspection method, namely the measuring electrode contact resistance and electrode polarization voltage estimate adhesion layer.
Indirect method of specific operations, see section 9 of this chapter.
5, check the flow chart of converter fault inspection item 11.
Methods to examine contemporary electromagnetic flow meter transducer to PCB spare parts and replacement method is often used to try to troubleshoot.
In this paper, published by the embellish of instrument science and technology co. , LTD. )
The previous: intelligent electromagnetic flowmeter under different fault types and check the flow chart of an article: electromagnetic flowmeter output signal flow chart of shaking when check and response
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