KR101181008B1 - Method for diagnosing of real-time performance of motor-operated valve and diagnosing system using the same - Google Patents

Abstract

The present invention discloses a real-time performance diagnosis method of a motor drive valve and a diagnosis system using the same that can monitor in real time the operating state of the motor drive valve and the damage state of the valve and the driver component using the stem friction coefficient of the driver. The real-time performance diagnosis method of the motor drive valve according to the present invention is to determine the stem friction coefficient average value from the torque and thrust value acting on the stem 7 of the valve 1 when the motor drive valve 1 is first installed. Performing a preliminary test for the subject; Setting a stem friction coefficient diagram, an upper limit value and a lower limit value based on the average value of the stem friction coefficient obtained in this preliminary test; Calculating the torque and thrust value acting on the stem 7 at each operation of the valve 1 to obtain a stem friction coefficient value for each stroke length of the valve; Determining whether the stem friction coefficient value is within an upper limit value and a lower limit value range of the stem friction coefficient diagram; And when the stem friction coefficient value is within the upper limit value and the lower limit value range of the stem friction coefficient diagram, determining that the valve is in a normal state, and generating an alarm when the stem friction coefficient value is outside the range.

Description

Method for diagnosing of real-time performance of motor-operated valve and diagnosing system using the same

The present invention relates to a motor drive valve, and in particular, a real-time performance diagnostic method of the motor drive valve that can monitor in real time the operating state of the motor drive valve and the damage state of the valve and the actuator parts using the stem friction coefficient of the driver and It relates to the diagnostic system used.

In general, various types of valves are installed in a power plant or various industrial plants to block or regulate the flow of fluid such as water and air, and these valves play an important role in the operation and safety of the system.

In particular, a valve using an electric motor as a power source for driving the valve is called a motor-operated valve (MOV), and the force generated from the motor is a valve stem of an actuator through various types of gear connections. And to the disk to perform the opening or closing of the valve.

In the case of the conventional motor drive valve, it is possible to detect only whether the opening or closing of the valve is completed by the operation of the limit switch or the torque switch installed in the valve. In this case, it is possible to know whether the valve is open or closed, but whether there is no problem in the opening and closing operation process or whether there is no abnormality or damage to the parts. In other words, it can be seen that the valve is in an abnormal state only when a serious failure or breakage of the valve occurs. In severe cases, it may cause a serious safety and economic loss by causing the power plant to shut down or cause a safety accident. have.

In order to solve this problem, recently, valve performance diagnostic equipment has been developed, and a method of diagnosing an operation state of a valve and an abnormality of a component has been applied. However, this means that diagnostic equipment is very expensive, and diagnostic test methods and signal analysis methods are complicated.

In addition, it is possible to test only during shutdown for maintenance of the power plant, so it is impossible to monitor the operation performance in real time every time the valve is operated.

Currently, there is no method to detect the abnormal state of the valve and the abnormal state of the component in real time every time the valve is operated while the motor driving valve is operating. Especially, the method of evaluating the valve performance by the stem friction coefficient only. No algorithm has been developed.

A schematic configuration of a conventional motor drive valve (hereinafter simply referred to as a 'valve') and an actuator, which is typically installed in a piping system of a power plant, is shown in FIGS. 1 and 2.

As shown in FIG. 1, the valve 1 is opened and closed by receiving the power of the motor 3 through the driver 2. FIG. 2 schematically shows the internal configuration of FIG. 1, referring briefly to the operation of the valve 1.

When the valve operation signal is input and the motor 3 rotates, the stem nut 6 rotates via the pinion gear 4 and the worm gear 5. Accordingly, as the stem 7 engaged with the stem nut 6 in a threaded manner is raised or lowered, the valve disc 8 provided at the lower end of the stem 7 is separated from the valve sheet 9 or adhered to the pipe ( 10) to open and close the fluid flow to open or block.

That is, the rotational torque generated by the motor 3 is transmitted to the stem nut 6 through the gears 4 and 5, and the torque of the stem nut 6 is converted into the thrust of the stem 7. Here, if it is possible to derive and monitor a variable that can define the transformation and correlation of the force generated between the torque of the stem nut (6) and the thrust of the stem (7), which is a key element of the power transmission process required for valve operation, Normal and abnormal conditions during opening and closing of the valve may be accurately identified in a relatively simple manner.

However, the torque is converted into the thrust while the stem nut 6 and the stem 7 are engaged.

Since friction occurs between the threaded portion of the stem nut 6 and the threaded portion of the stem 7 in the process, in the present invention, a constant representing the magnitude of the friction is defined as a stem friction coefficient. Experimental results for various valves show that each valve has a specific stem friction coefficient depending on the design and operating environment of the stem nut (6) and stem (7). In the normal operating state, the stem friction coefficient is continuously maintained within a certain range, and in abnormal conditions, the characteristic stem friction coefficient appears depending on the cause, and eventually, the stem friction coefficient is the operating state of the valve 1 and the actuator 2. It turns out that can be a variable that represents.

In other words, by analyzing the stem friction coefficient, it is possible to grasp the transmission state of the force from the motor 3 to the stem nut 6, so that the operating state of the driver 2 can be known. In addition, the transfer state of the load from the valve disc 8 to the stem 7 can be grasped so that the operation state of the valve 3 can also be known. Therefore, when the stem friction coefficient is derived and analyzed over the entire stroke in which the valve 1 operates, it is a technical background of the present invention that the normal operation and abnormal operation of the valve 1 and the abnormal state of the main parts can be grasped.

In the conventional diagnostic test method of the motor drive valve, the torque, thrust, voltage, current, etc. should be measured, and each measured signal value must be comprehensively analyzed to find out whether the valve and / or actuator are in an abnormal state. In addition, there was a disadvantage that a professional manpower should be input for test and signal analysis.

The present invention provides a real-time performance diagnostic method of the motor drive valve and a diagnostic system using the same, which can grasp the normal and abnormal state of the operation in real time during operation of the motor drive valve, and can check the abnormal state of the valve and the actuator parts. For the purpose of

According to one aspect of the present invention for achieving the above object, when the motor drive valve is first installed, performing a preliminary test for determining the stem friction coefficient average value from the torque and thrust value acting on the stem of the valve Wow; Setting a stem friction coefficient diagram, an upper limit value and a lower limit value based on the average value of the stem friction coefficient obtained in this preliminary test; Calculating a torque and a thrust value acting on the stem at each operation of the valve to obtain a stem friction coefficient value for each stroke length of the valve; Determining whether the stem friction coefficient value is within an upper limit value and a lower limit value range of the stem friction coefficient diagram; And determining that the valve is in a normal state when the stem friction coefficient value is within the upper and lower limits of the stem friction coefficient diagram, and generating an alarm when out of the range. do.

In the preliminary test step of the present invention, a strain gauge sensor is installed on the stem of the valve, the valve operation test is performed to measure the torque and the thrust value, and the measured torque and the thrust value are calculated by the following equation,

Calculate the stem friction coefficient (μ _s ) by Where μ _s is the stem friction coefficient, torque and thrust are the torque and thrust values measured by the strain gauge sensor, α is the half angle of the stem thread, θ is the stem screw lead angle, and d is [Stem Outer Diameter-Stem Pitch / 2]. Indicates.

In the preliminary test step, at least three repetition tests are performed to obtain an average value of the stem friction coefficient for each section of the operation stroke of the valve, and to obtain the stem friction coefficient diagram as a reference by using the average value as a reference value. ,

,

,

It is characterized by setting the upper limit value and the lower limit value, respectively. Where μ _s , _{upper limit} is _{upper limit} of stem friction coefficient, μ _s , _{lower limit} is _lower stem friction coefficient, SPR is spring loaded, SLD is lower stem lubrication, Serr is strain gauge sensor measurement error, and TSR is torque switch repeatability. .

In the present invention, the step of determining whether the measured value of the stem friction coefficient is within the upper and lower limits of the stem friction coefficient diagram determines whether the current value is greater than the value of the reference value X 1.5, and if the value is high-high stem Generating a coefficient of friction alarm and, if small, generating a high-stem friction coefficient alarm.

Further, in the present invention, the step of determining whether the measured value of the stem friction coefficient is within the upper and lower limits of the stem friction coefficient diagram may be determined whether the current value is smaller than the reference value × 0.5, Generating a low stem friction coefficient alarm and, if greater, generating a low stem friction coefficient alarm.

On the other hand, according to another aspect of the present invention, a plurality of valves for opening and closing the fluid flow in the pipe while operating by a motor via a driver: a strain gauge sensor provided in the stem of the driver to measure torque and thrust value; A smart card having a calculation and storage device connected to the strain gauge sensor via a cable to calculate a stem friction coefficient value from the measured torque and thrust value to determine whether the valve is in a normal state; And a display device configured to receive and display information from the smart card by wire or wirelessly.

The smart card is configured to determine whether the valve is in a normal state by using the diagnostic method according to the present invention, and to store data measured in real time.

The present invention utilizes a stem friction coefficient analysis to diagnose the current operation state of the valve by the algorithm embedded in the smart card during valve operation, and to notify the administrator in real time of the result, and also the operation state information of the valve is maintained at every valve operation. As a result, it can accumulate in smart cards and analyze performance degradation trends of valve and actuator parts. Therefore, real-time monitoring of the valve is possible at a low cost in power plants, which prevents the operation of the power plant due to valve malfunction or accident, improves the safety of operation, and reduces the cost of valve breakage and replacement by performing maintenance in advance when abnormal symptoms are detected. And life extension effect can be expected.

1 is a schematic perspective view of a conventional motor drive valve.
FIG. 2 is a schematic cross-sectional view of the motor drive valve of FIG. 1.
3 is a representative diagram of the stem friction coefficient at the opening stroke of the valve.
4 is a representative diagram of the stem friction coefficient seen in the closing stroke of the valve.
5 is an illustration of a stem friction coefficient diagram that appears when the valve is in an abnormal state in the opening stroke.
6 is an illustration of a stem friction coefficient diagram that appears when the valve is in an abnormal state in the closed stroke.
7 is a schematic configuration diagram of a diagnostic system for controlling and operating a plurality of motor drive valves according to the present invention.
8 is a flowchart according to the algorithm for diagnosis and determination of the motor drive valve in the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same parts as the prior art.

The present invention provides a technical algorithm that can check the operating state of valves and actuators through the analysis of stem friction coefficients, thereby minimizing the analysis parameters, determining the analysis process and the presence of abnormalities, and minimizing the measuring device. The data accumulated in the smart card is also minimized so that the motor driving valve can be monitored in real time at the lowest possible cost.

In general, the operation of the motor drive valve can be divided into an unseating section, a running section, a limit switch trip section, and an open completion section in the case of an open stroke, and a closing start section, a running section, and a closed stroke. It can be divided into seating section, torque switch trip section and closing completion section. In the case of normal operation of the valve, the stem friction coefficient generated in each of the above sections maintains a certain range of values suitable for the characteristics of each section.However, in the case of abnormal operation of the valve, the stem friction coefficient is out of a certain range. Will be displayed.

For example, when the packing force is excessively fastened, the stem friction coefficient is very large in the running section, and when the stem 7 is stopped, the stem friction coefficient suddenly increases in a certain section of the stem. Therefore, the stem friction coefficient in the normal operation state is analyzed as the reference value for the entire stroke section of the valve, and the stem friction coefficient is derived every time the valve is operated. It can be.

Here, the stem friction coefficient represents the friction generated between the actuator stem nut 6 and the valve stem 7 as a dimensionless constant value in the process of transferring power from the actuator 2 to the valve. The present invention proposes a method for identifying the operating state of the valve and the abnormal state of the valve and the actuator parts by monitoring the change of the stem friction coefficient during the entire stroke of the valve operation.

Referring to FIG. 2, a strain gauge sensor 11 is installed on the valve stem 7 to derive a stem friction coefficient, and torque and thrust are measured at each valve operation. The strain gauge sensor 11 preferably uses a strain gauge sensor capable of simultaneously measuring torque, which is a rotational force transmitted from the stem nut 6 to the stem 7, and a thrust, which is a vertical force, during valve operation. In addition, in order to increase the accuracy of the measured value, the strain gauge sensor 11 must be installed at the same diameter of the stem 7 and the smooth surface thereof.

The strain gage sensor 11 has a small deformation in the stem 7 due to the compressive force and the tensile force transmitted to the valve operating system 7, which is converted into a resistance and converted into a torque or thrust value. At this time, the stroke distance of the valve is set to the limit switch 12 built in the driver 2 and the stroke start point and the end point are respectively set so as to receive the operation signal of the limit switch 12 every time the valve is operated. When the torque value and thrust value are measured for the entire stroke and closed stroke, the stem friction coefficient can be obtained by applying these values to Equation (1) below, and the stem friction coefficient diagram for the entire stroke of the valve operation can be prepared.

.....(1)

.....(One)

Where μ _s is the stem friction coefficient, torque and thrust are the torque and thrust values measured by the strain gauge sensor, α is the half angle of the stem thread, θ is the stem screw lead angle, and d is [Stem Outer Diameter-Stem Pitch / 2]. Indicates.

When the stem friction coefficient diagram for the entire stroke is drawn, the upper and lower limits of the stem friction coefficient corresponding to the normal operating range are determined based on the values. Here, the upper and lower limits of the normal operating range mean that the natural performance of parts and sensor and control switch errors may occur due to continuous repetitive operation for a long time after the valve is first installed. Will change within.

Here, it is possible to set a specific range where the degree of change of the stem friction coefficient can be regarded as a normal section where there is no problem in the normal operation of the valve and the integrity of the component. That is, if the change in the stem friction coefficient is within the above specific range, it can be determined that there is no problem in valve operation. However, if it exceeds the range, it may be determined that there is a problem in the valve operation, and the criteria of the upper limit value and the lower limit value of the stem friction coefficient that can allow such valve operation should be set.

Equations (2) and (3) below are formulas for calculating the upper and lower limits of the stem friction coefficient, respectively, taking into account the deterioration in valve components and variables as the valve continues to operate repeatedly.

.....(2)

.....(2)

.....(3)

..... (3)

Where μ _s , _{upper limit} is stem friction coefficient upper limit, μ _s , _{lower limit} is stem friction coefficient lower limit, SPR is Spring Pack Relaxation, SLD is Stem Lubricant Degradation, and Serr is strain gauge The measurement error, TSR, represents Torque Switch Repetability.

3 is a representative diagram of the stem friction coefficient seen in the open stroke of the valve. The dotted line 3a is a stem friction coefficient diagram when the valve is operated in the absence of the fluid pressure during valve operation, and the solid line 3b is a stem friction coefficient diagram when the valve is operated under the pressure of the fluid during valve operation. The stem friction coefficient is divided into unsitting section (A-B), running section (B-C), limit switch trip section (D-E), and open completion section (E-F).

The unsitting section A-B is a state in which the valve disc 8 first comes out of the valve seat 9. At this time, a large thrust is required to overcome the mutual friction force between the valve disc 8 and the valve seat 9, and the friction between the stem nut 6 and the stem 7 also occurs the greatest.

In the running section B-C, the valve disc 8 has come out of the valve seat 9. At this time, since only the friction force with the packing installed to prevent the leakage of the stem portion, the friction between the stem nut (6) and the stem (7) is relatively low and acts constantly, and occupies most of the opening stroke.

The limit switch trip section D-E is a section in which the stem 7 moves to a preset opening distance and the limit switch 12 is operated, and the valve movement is stopped.

The opening completion section E-F is a section in which the motor 3 is stopped and the stem nuts 6 and the stem 7 are completely stopped while being in close contact with each other. At this time, the stem friction coefficient is slightly increased.

4 is a representative diagram of the stem friction coefficient shown in the closing stroke. The dotted line 4a is a state where there is no pressure of the fluid during valve operation, and the solid line 4b is a state where there is a pressure of the fluid, and the stem friction coefficient is a closing start section (AB), a running section (BC), and a seating section (CD). It is divided into limit switch trip section (DE) and closed completion section (EF).

The closing start section (A-B) is the section where the closing first starts.

There is a tendency for the stem nut 6 and the stem 7 which are in close contact by the opening stroke to be slightly loosened and the stem friction coefficient to be slightly lower. When the pressure of the fluid is present, the pressure of the fluid acts as a force to block the closing of the valve, and the stem nut 6 and the stem 7 are applied, so that the stem friction coefficient starts and continues at a slightly higher value. Shows.

The running section (B-C), like the opening stroke, has only the packing frictional force, and moves while maintaining a constant stem friction coefficient value.

The seating section C-D is a section in which the valve disc 8 and the valve seat 9 first contact each other, and the stem friction coefficient after seating exhibits a constant value which is almost straight. If the fluid pressure is present, the stem friction coefficient after seating is slightly lowered to a constant value.

The limit switch trip section D-E is a section in which the limit switch operates and the movement of the valve is stopped by reaching a preset closing distance.

The closing completion section (EF) is a section in which the motor 3 is completely stopped and the closing stroke is completed. The stem friction coefficient is constant in two sections, namely, the limit switch trip section DE and the closing completion section EF. Will continue.

5 and 6 show examples of stem friction coefficient diagrams that appear when the valve is in an abnormal state in the opening and closing strokes, respectively.

5 and 6, the dotted lines 5a and 6a represent the stem friction coefficient diagrams in the normal state, and the solid lines 5b and 6b represent the abnormal state. The boxes indicated by the dashed dashed line for each section represent the upper limit values 5c and 6c and the lower limit values 5d and 6d in consideration of the natural performance degradation of the part and the error of the sensor based on the steady state stem friction coefficient distribution. If the stem friction coefficient is within the upper limit value and the lower limit value, it is judged to be a natural deterioration phenomenon due to repeated operation or a slight abnormal condition requiring no further action.

However, in FIG. 5, it can be seen that the stem friction coefficient diagram of the solid line 5b springs up at a predetermined interval in the running section as indicated by the reference numeral 5e. This can be determined as a case where a part of the thread of the stem nut 6 or the stem 7 is broken.

As shown in FIG. 6, it can be seen that the stem friction coefficient indicated by the solid line 6b exceeds the reference upper limit 6c in all sections. This indicates that the friction between the stem nut 6 and the stem 7 is abnormally large, which may be determined by the solidification of the stem lubricant or excessive load (excessive tightening of the packing, etc.). As in the analysis example of the abnormal stem friction coefficient diagram, the stem friction coefficient analysis can find most of the abnormal operation states and damages of parts generated in the valve and the actuator.

7 shows a conceptual diagram of controlling and operating a plurality of smart motor drive valves according to the present invention. Reference numeral 13 is a smart card attached to the driver 2, and a probe for detecting the operation of the strain gauge sensor 11 and the limit switch 12 via a cable 14 to the smart card input terminal (not shown). ) Is connected. The input measured values calculate the stem friction coefficient value for each stroke by the calculation and processing device 15 provided in the smart card 13, and the calculated values are the normal stem friction coefficient values of the corresponding valves which are previously inputted for each section. The results are compared with each other to finally determine a normal or abnormal state.

That is, when it is determined that the stem friction coefficient value is in an abnormal state, the estimated cause is analyzed. Data measured and collected every time valve operation, analysis, and judgment information are all stored in the memory (not shown) of the smart card 13, and transmitted to the display device 16 of the remote control room by wire or wireless Is designed to see all the information. Furthermore, in the above manner, it can be designed to monitor several valves at the same time in real time.

8 is a flowchart according to an algorithm of diagnosis and determination of a smart motor drive valve capable of self-diagnosis of valve performance using the stem friction coefficient measurement and analysis technique described above. First, when the valve 1 is first installed, a preliminary test is performed to determine the stem friction coefficient reference value of the valve. The strain gauge sensor 11 is installed on the stem 7 of the valve 1 to perform a valve operation test (S1), and the torque and thrust value are measured (S2).

The measured torque and thrust value calculate the stem friction coefficient by the stem friction coefficient calculation formula (1), and display a value for each section for the whole stroke (S3). At least three repetition tests (S4) are performed from steps (S1) to (S3) and the average value of the stem friction coefficient for each section is obtained (S5). Using this average value as a reference value, the stem friction coefficient chart and the upper limit value / lower limit value as reference values are set (S6). All the above calculations are calculated by the calculation and processing device 15 in the smart card 13, and stored as a reference value diagram to be compared with the stem friction coefficient collected at every valve operation.

When the stem friction coefficient reference value diagram is completed (S6), the torque and thrust value are automatically measured (S2 ') every time the valve 1 is operated for the lifetime of the valve (S1'), and the stem friction coefficient for each section is calculated. Is calculated (S3 '), the stem friction coefficient diagram is prepared (S6'), and the obtained stem friction coefficient is compared with the stem friction coefficient reference value inputted by the control logic set in the smart card (13). It is determined whether there is a section deviating from (S7).

That is, when the currently calculated stem friction coefficient value is larger than the reference upper limit value (S8), it is determined whether the current stem friction coefficient value is larger than [reference value x 1.5] (S9), and when it is large, it is high-high ( high)-activates the system friction coefficient alarm (S10), otherwise operates the high-stem friction coefficient alarm (S11).

If the present value is smaller than the reference upper limit in step S8, it is determined whether the present value is smaller than the reference lower limit (S12).

X 0.5] or less (S13). If the present value is small, the low-low-stem friction coefficient alarm is activated (S14), otherwise the low-stem friction coefficient is activated. Operate the alarm (S15).

On the other hand, when the present value is inside the reference upper limit value and the reference lower limit value box, it is determined as a normal state (S16).

In the step S10 or S14, when the high-high-stem friction coefficient (or low-low-stem friction coefficient) alarm is operated, it means that the operation state of the valve 1 is a serious abnormal state. Therefore, the administrator should immediately stop the valve operation when such an alarm occurs, check the valve status and eliminate the cause. By the way, when the high-stem friction coefficient (or low-stem friction coefficient) alarm is activated in step S11 or S15, although the operating state of the valve 1 is abnormal, it is not an emergency enough to take immediate action. Therefore, watch the trend more closely and check the valve when it is not working or during regular maintenance and eliminate the cause.

The above description describes a preferred embodiment of the present invention, but the present invention is not limited thereto. Those skilled in the art should understand that various changes and modifications can be made within the scope of the present invention.

As described above, the present invention is equipped with a hardware device (including a sensor and a smart card) to which the stem friction coefficient analysis technique and algorithm proposed in the present invention is applied to an existing motor driving valve installed in a power plant. Type motor drive valve. In addition, many smart motor drive valves can be monitored at one place through the display device of the main control room, thereby reducing installation costs and configuring an efficient monitoring system. In particular, many of the accident prevention and safety function valves of nuclear power plants are motor-driven valves, and when the present invention is applied, the abnormal state of the valves can be detected in advance, thereby improving the safety and operation of the power plant, and greatly improving the life of the valve. It is expected to be reaped.

1: motor drive valve 2: actuator
3: motor 6: stem nut
7: stem 8: valve disc
9: valve seat 11: strain gauge sensor
12: limit switch 13: smart card
14: Cable 15: Computing and Processing Unit
16: display device

Claims (7)

delete Performing a preliminary test for determining the stem friction coefficient average value from the torque and thrust value acting on the stem 7 of the valve 1 when the motor drive valve 1 is first installed;
Setting a stem friction coefficient diagram, an upper limit value and a lower limit value based on the average value of the stem friction coefficient obtained in this preliminary test;
Calculating the torque and thrust value acting on the stem 7 at each operation of the valve 1 to obtain a stem friction coefficient value for each stroke length of the valve;
Determining whether the stem friction coefficient value is within an upper limit value and a lower limit value range of the stem friction coefficient diagram; And
If the stem friction coefficient value is within the upper and lower limits of the stem friction coefficient diagram, it is determined that the valve operation is in a normal state, and if the stem friction coefficient value is out of range, an alarm is generated.
In the preliminary test step, the strain gauge sensor 11 is installed on the stem 7 of the valve 1, the valve operation test is performed to measure the torque and the thrust value, and the measured torque and the thrust value are as follows. A real-time performance diagnostic method of a motor drive valve, characterized in that for calculating the stem friction coefficient (μ _s ) by the calculation formula.

Where μ _s is the stem friction coefficient, torque and thrust are the torque and thrust values measured by the strain gauge sensor, α is the half angle of the stem thread, θ is the stem screw lead angle, and d is [Stem Outer Diameter-Stem Pitch / 2]. Indicates. The method of claim 2, wherein in the preliminary test step, at least three repetition tests are performed to obtain an average value of the stem friction coefficient for each section of the operation of the valve, and to obtain a stem friction coefficient chart as a reference using the average value as a reference value. Real-time performance diagnostic method of the motor drive valve, characterized in that for setting the upper limit value and the lower limit value of the stem friction coefficient using the following equations.

,

Where μ _s , _{upper limit} is _{upper limit} of stem friction coefficient, μ _s , _{lower limit} is _lower coefficient of stem friction, SPR is spring loaded, SLD is lower stem lubrication, Serr is strain gauge sensor measurement error, and TSR is torque switch repeatability. . The method of claim 2, wherein the determining whether the measured value of the stem friction coefficient is within the upper and lower limits of the stem friction coefficient line is determined by determining whether the current value is greater than the value of the reference value × 1.5, and Generating a high stem friction coefficient alarm and, if small, generating a high stem friction coefficient alarm. The method of claim 2, wherein the determining whether the measured value of the stem friction coefficient is within the upper and lower limits of the stem friction coefficient line comprises: determining whether the current value is smaller than a reference value × 0.5, and if the value is low, Generating a low stem friction coefficient alarm, and generating a low stem friction coefficient alarm if it is large. A plurality of valves (1) for opening and closing the fluid flow in the pipe (10) while operating by the motor (3) via the driver (2):
A strain gauge sensor 11 mounted on the stem 7 of the actuator to measure torque and thrust values;
Computation and storage device 15 connected to the strain gauge sensor 11 via a cable 14 to calculate the stem friction coefficient value from the measured torque and thrust value to determine whether the valve 1 is in a steady state. Smart card 13; and
Including a display device 16 to receive and display the information from the smart card 13 by wire or wireless,
The smart card 13 determines whether the valve 1 is in a steady state by using the method according to any one of claims 2 to 5, and stores the data measured in real time. Valve real-time performance diagnosis system.

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