KR100336210B1 - Diagnostic circuit for power plant valves in operating - Google Patents

Abstract

The present invention compares the compression force and the tension applied to the limit / torque switch and stem applied when the valve is driven to detect the optimum operating point of the valve, and detects the signal of the resistance of the strain gauge for the accuracy of the measurement. The present invention relates to an apparatus for diagnosing the performance of a valve in operation to relieve an unsafe element of a valve system and to prevent burnout of a component of a valve by readjusting a torque switch set value in terms of force.

To this end, the present invention provides a strain gauge for measuring the amount of change in strain, such as mechanical stress, pressure, force, displacement, etc. applied to a valve in operation, and the balancing and signal amplification of the amount of change in electrical resistance measured by the strain gauge. A strain gage processing unit to perform the operation, a linear variable differential transformer (LVDT) that detects the position of the valve stem and converts an electrical signal into a displacement amount according to the change in electrical resistance measured by the strain gauge, and the valve in an open / closed state of the valve. The load cell outputs a force sensing signal for detecting the valve operating state through the change of the stress and tension of the stem according to the operating state of the stem, and the opening and closing operation of the driving valve driving motor (MOV) is detected to drive the M0V or Limit switch which stops driving and outputs electric signal accordingly, and on / off of this limit switch Torque switch that mechanically stops valve operation when operation stops, and current sensing unit that detects operation current of valve drive motor to detect various defects such as valve disc stuck, stem physical damage, and abnormal operation of actuator. And a motor applied voltage detector for detecting a voltage applied to the valve driving motor to obtain a line voltage without phase change, and detecting an on / off state of a limit / torque switch and converting it into a low AC voltage of an insulated state. A switch signal processing unit for outputting to the signal interface unit, a transducer for firstly amplifying the driving voltage signal and the driving current signal of the MOV, multiplying them by phase, synthesizing and secondly amplifying the power signal, and outputting to the signal interface unit; Voltage, current and power signals and other strain gauges output from the motor-voltage sensing unit, current sensing unit and transducer It receives the operation signals output from the processing unit, the LVDT, the load cell, and the limit switch, respectively, and converts them into analog signals suitable for the input level of the processing control interface card. ) Is configured to include a signal interface for interfacing the data with the sensor, and measure the mechanical stress applied to the valve in operation using a strain gauge, convert the displacement according to the electrical signal as an LVDT, and detect the drive through a valve performance diagnosis device. The signal is determined by PC through the signal interface along with the voltage, current, and power of the motor, and the collected various signal data are collected and processed to ensure the safety of the valve in operation and to check the soundness during operation. There is an effect that can contribute to improving the reliability of operation.

Description

Diagnostic circuit for power plant valves in operating

The present invention relates to an apparatus for diagnosing performance of a valve in operation, and in particular, compares a compression force and a tension force applied to a limit / torque switch and a stem generated during valve operation to detect an optimum operating point of a valve, and to improve accuracy of measurement. By adjusting the torque switch's setting value by converting the resistance signal of the strain gauge into force using a PC, it is possible to remove the unsafe element of the valve system and prevent the burnout of the valve components. A performance diagnostic device.

At present, the diagnostic test on the safety of MOV (Motor Operated Valve) related to nuclear power plant safety in Korea is subject to regulation by KINS (Korea Institute of Nuclear Safety). However, no diagnostic tests have been considered for energized MOVs, which have much more frequent shutdowns and start-ups than nuclear power plants.

In order to improve this, a diagnostic system based on a computer system using various sensors has been proposed. However, this is accompanied by the inconvenience of frequent inspection and calibration. This problem is caused.

Therefore, the present invention has been proposed to solve the above problems of the prior art, and detects the optimum operating point of the valve by comparing the compression force and the tension force applied to the limit switch and the stem when the valve is driven, and for the accuracy of the measurement The present invention provides a valve performance diagnosis apparatus to convert the signal of the strain gauge resistance into a force using a computer to readjust the set value of the torque switch to remove the unsafe element of the valve system and to prevent the burnout of the valve component.

In order to achieve the above object, the present invention provides a strain gauge for measuring strain variation of mechanical stress, pressure, force, displacement, etc. applied to a valve in operation as an electrical resistance variation, and balancing of electrical resistance variation measured in a strain gauge. Strain gage processing unit that performs signal amplification, linear variable difference transformer (LVDT) that detects the position of valve stem and converts the displacement according to the change in electrical resistance measured by the strain gage, and the valve open / closed state. The load cell outputs a force sensing signal for detecting the operating state of the valve by changing the stress and tension of the stem according to the operating state of the valve stem, and the opening and closing operation of the operating valve driving motor (MOV) is detected. Limit switch and limit switch which drive or stop and output electric signal accordingly Operation of the valve drive motor to identify various faults such as a torque switch that mechanically stops the valve drive when the on and off operation of the motor is stopped, and the stem of the valve disc, the physical damage of the stem, and the abnormal operation of the actuator. Current sensing unit for detecting current, motor applied voltage sensing unit for detecting voltage applied to valve driving motor to obtain line voltage without phase change, and insulation state by sensing on / off state of limit / torque switch The switch signal processing unit converts the low AC voltage into the signal interface and outputs the signal signal to the signal interface. An output transducer, and voltage, current, and power signals outputted from the motor-voltage sensing unit, current sensing unit, and transducer, respectively. It receives the operation signals output from the strain gauge processor, LVDT, load cell and limit switch, and converts them into analog signals suitable for the input level of the card for processing control interface, and converts them into digital signals through the card for processing control interface. Is configured to include a signal interface for interfacing data with < RTI ID = 0.0 >

1 is an overall block diagram of a valve performance diagnostic apparatus according to the present invention.

Figure 2 is a detailed block diagram of a valve performance diagnostic apparatus according to the present invention.

Figure 3 is a connection state between the voltage / current detection unit and the transducer according to the present invention.

4 is a detailed block diagram of a transducer according to the present invention;

* Explanation of symbols for main parts of drawings *

1: strain gage 1A: strain gage treatment

2: Linear Variable Difference Transformer (LVDT) 3: Load Cell

4: Limit / Torque Switch 4A: Limit / Torque Switch Indicator

5: current sensing unit 6: motor applied voltage sensing unit

10: valve performance diagnostic device 11: switch signal processing unit

12: Transducer 13: Signal Interface

20: Card for Process Control Interface (PCI) 30: Fish (PC)

121: first signal amplifier 122: second signal amplifier

123: multiplier 124: synthesizer

125: third signal amplifier

Hereinafter, the present invention will be described with reference to the accompanying drawings.

1 is a block diagram showing the overall configuration of the valve performance diagnostic apparatus according to the present invention, which measures the amount of strain change in mechanical stress, pressure, force, displacement, etc. applied to a valve in operation (not shown) as an electrical resistance change amount. The strain gauge 1, the strain gauge processing unit 1A which performs balancing and signal amplification of the electrical resistance change measured by the strain gauge 1, and the position of the valve stem (not shown) are detected. And a linear variable differential transformer (LVDT) 2 for converting an electrical signal into a displacement amount according to the electrical resistance change measured by the strain gauge 1, and the operation of the valve stem in an open / closed state of the valve. Load cell (3) which outputs a force sensing signal for detecting the operating state of the valve by changing the stress and tension of the stem according to the state, and the valve driving in operation Limit switch (4) for detecting the opening and closing operation of the motor (MOV) to drive or stop the MOV, and outputting an electrical signal, and a torque switch (4) for mechanically stopping the valve driving when the on / off operation of the limit switch is stopped. And a current sensing unit 5 which detects starting and operating current of the valve driving motor MOV in order to identify various defects such as sticking of the valve disc, physical damage of the stem, and abnormal operation of the actuator. And a motor applied voltage detection unit 6 for detecting a voltage applied to the valve driving motor MOV to obtain a line voltage without phase change, and a valve performance diagnosis device for comprehensively diagnosing valve performance in operation. 10).

FIG. 2 is a detailed block diagram of the valve performance diagnosis apparatus 10 shown in FIG. 1.

A switch signal processing unit 11 for detecting the on / off state of the limit / torque switch 4 and converting it into a low AC voltage in an insulated state and outputting the signal to the signal interface unit 13, a drive voltage signal and a drive current of the MOV. A transducer 12 for outputting a power signal obtained by first amplifying the signal, multiplying it by phase, and synthesizing the second amplified signal to the signal interface unit 13, the motor applied voltage sensing unit 6, and a current sensing unit ( 5) and voltage, current, and power signals output from the transducer 12 and other strain gauge processing units 1A, LVDT 2, load cell 3, and limit / torque signal processing units 11, respectively. Signal interface that receives an operation signal and converts it into an analog signal suitable for the input level of the processing control interface card 20, and converts it into a digital signal via the processing control interface card 20 to perform data interfacing with the PC. It is configured to include a 13.

Reference numeral 4A in FIG. 2 denotes a limit / torque switch indicator.

FIG. 3 is a circuit diagram showing in detail the connection relationship between the transducer 12, the motor-applied voltage detector 6, and the current detector 5 shown in FIG. 2. FIG. The first to third current sensors (CM1 to CM3) for detecting the current flowing in each phase (R, S, T) of the MOV, and the motor applied voltage detection unit 6 is applied to the primary side It consists of a three-phase lottery transformer (T) for converting the motor applied voltage (AC 220V or 480V) to the predetermined voltage (AC 110V) on the secondary side and outputting the line voltage without phase change in the YY connection.

In addition, the voltage induced on the secondary side of the three-phase lottery transformer T is preferably converted to AC 110V for signal isolation.

FIG. 4 is a detailed block diagram of the transducer 12 shown in FIGS. 2 and 3, wherein the first and second amplifiers 121 and 122 first amplify signals for voltage and current, respectively. ), A multiplier 123 multiplying the output signals of the first and second amplifiers 121 and 122 by phase, and a three-phase output signal of the multiplier 123 according to a control input signal (Z Input) state. A synthesizer 124 for synthesizing and a third amplifier 125 for amplifying the output signal of the synthesizer 124 secondly and outputting a power signal (W Output).

The operation of the present invention configured as described above will be described with reference to FIGS.

As is well known, in order to accurately diagnose the operating characteristics of the operating valve, measurement of operating parameters must be preceded.

The above operating parameters are largely divided into powers according to motor applied voltages, starting and operating current load conditions. In addition, the limit switch operation signal must also be detected in order to detect the characteristics of the control circuit.

As described above, the operating parameters can be displayed by a characteristic containing a time element by detecting abnormal operation of the valve as an electric signal, and can also check whether the control circuit is normal according to the limit switch setting.

Under this background, the present invention proposes a characteristic detection circuit of a motor which is a main driving source of a valve in operation, and determines various sensing data detected by the characteristic detection circuit using a general-purpose PC, thereby ensuring safety of the valve. This is to secure the reliability and improve the operation of nuclear power plants.

First, the strain change amount according to the mechanical stress, pressure, force, displacement, etc. applied to the valve in operation as the strain gauge 1 is measured, converted into an electric resistance change amount, and output to the strain gauge processing unit 1A.

In the strain gauge part 1A, since the change value of the electrical resistance output from the strain gauge 1 is very weak, the signal amplification is performed at an appropriate level and the change in the electrical resistance is unstable. It is applied to the input terminal INPUT of the device 10.

On the other hand, the LVDT (2) detects the position of the valve stem, not shown, and converts the displacement amount according to the electrical resistance change measured by the strain gauge (1) into an electrical signal to the input end of the valve performance diagnostic apparatus (10) ( INPUT).

In addition, the load cell 3 applies a force detection signal to the input terminal INPUT obtained by detecting an operation state of the valve through a change in stress and tension of the valve stem in an open or closed state of the valve.

On the other hand, the limit switch of the limit / torque switch 4 detects the opening and closing operation of the valve driving motor (MOV) in operation to drive or stop the MOV, and applies the electrical signal to the input terminal (INPUT), In this case, the torque switch forcibly stops the valve drive by mechanical operation when the limit switch stops the on and off operation.

In addition, the current sensing unit 5 detects starting and operating currents of the valve driving motor MOV in order to identify various defects such as a stud of the valve disk, a physical damage of the stem, or abnormal operation of the actuator, which are not shown. The motor applied voltage detector 6 detects a voltage applied to the valve driving motor MOV, detects a line voltage without a phase change, and outputs the voltage to the valve performance diagnosis apparatus 10 shown in FIG. 1.

2, an operation of the valve performance diagnosis apparatus 10 including the switch signal processing unit 11, the transducer 12, and the signal interface unit 13 will be described.

The switch signal processor 11 detects the on / off state of the limit / torque switch 4 and outputs the switch signal SWITCH SIGNAL converted to a low AC voltage in an insulated state to the signal interface unit 13.

On the other hand, in the transducer 12, since the driving voltage signal of the MOV output from the motor application voltage sensing unit 6 and the driving current signal output from the current sensing unit 5 are input as weak DC low voltage signals, After amplifying, multiplying each of the output signals by phase and synthesizing them again, and outputting the power signal WATTSOUTPUT obtained by second amplifying the synthesized output signal to the signal interface unit 13.

The related operation of the current sensing unit 5, the motor applied voltage sensing unit 6, and the transducer 12 will be described in detail with reference to FIGS.

First, the current detecting unit 5 detects each operating current flowing in the three phases R, S, and T of the MOV using the first to third current sensors CM1 to CM3, and detects a corresponding current. The signal rule transducer 12 and the signal interface unit 13 are outputted.

For example, the first to third current sensors CM1 to CM3 may select and measure an alternating current in units of 20 A / 200 A, and output 2 V AC at 20 A current input.

The reason for detecting the driving current as described above is that the operating current of the valve is different because the load characteristics of the valve in operation change with the change of the flow rate. If the valve in operation has any defect, it has a direct influence on the motor which is the main driving source, which requires a current detection since it involves a sudden change in the motor operating current.

By detecting and analyzing the current in this way, it is easy to find faults such as sticking of the valve disc, physical damage of the stem, and abnormal operation of the actuator part.

On the other hand, the motor applied voltage detection unit YY connection the predetermined AC voltage AC110V induced on the secondary side according to the motor applied voltage (AC 220V or AC 480V) applied to the primary side of the three-phase lottery transformer T It converts into a line voltage (Line to Line) does not change the phase is output to the transducer 12 and the signal interface unit (13).

Accordingly, the transducer 12 primarily amplifies the signal X1 (X2) for the voltage output from the motor application voltage detector 6 through the first amplifier 121 as shown in FIG. The signal Y1 (Y2) with respect to the current output from the current sensing unit 5 is primarily amplified through the second amplifier 122.

Thereafter, the output signals X and Y of the first and second amplifiers 121 and 122 are multiplied by the multiplier 123.

By multiplying phase by phase, an output signal XY + Z obtained by combining the output signal of the multiplier 123 with the control input signal Z Input from the outside through the synthesizer 124 is obtained.

That is, since the voltage signal and the current signal related to the operation of the motor are input as the low voltage signal, it is necessary to synthesize these two signals.

Subsequently, the output signal XY + Z again outputs the power output signal WATTS OUTPUT generated by second amplification through the third amplifier 125 to the signal interface unit 13 as shown in FIG. . In this case, assuming that the control input signal Z input is '0', the power output signal WATTS OUTPUT becomes W = XY.

In the signal interface unit 13, current, voltage, and power signals output from the current sensing unit 5, the motor applied voltage sensing unit 6, and the transducer 12, and the other strain gauge processing unit 1A, respectively. , An operation signal output from the LVDT 2, the load cell 3, and the limit / torque switch signal processing unit 11 is input, and converted into an analog signal suitable for the input level of the card 20 for a process control interface, and process control The digital card is converted into a digital signal via the interface card 20 to perform data interfacing with the PC.

Thus, between the valve performance diagnosis device 10 and the PC (PC) through the signal interface unit 13

By interfacing various sensed signal data, the PC collects signals by storing, calculating and graphing these various data, so that the user can easily and precisely diagnose the performance of the valve in operation.

As described above, the present invention measures the mechanical stress applied to the valve in operation by strain gauge, converts the displacement according to the LVDT into an electrical signal, and detects the voltage, current and By discriminating the signal with the PC through the signal interface along with the power value, and collecting and processing the various signal data, it contributes to securing the safety of the valve in operation, checking the soundness during operation, and improving the reliability of nuclear power plant operation. It can work.

Claims (5)

Strain gauges that measure the amount of change in strain, such as mechanical stress, pressure, force, displacement, etc., applied to the valve in operation as a change in electrical resistance; A strain gauge processing unit for balancing an electrical resistance variation measured by the strain gauge and amplifying a signal; A linear variable difference transformer (LVDT) for detecting the position of the valve stem and converting an electrical signal into a displacement amount according to the electrical resistance change measured by the strain gauge; A load cell for outputting a force sensing signal for detecting an operating state of the valve by changing the stress and tension of the stem according to the operating state of the valve stem in the open / closed state of the valve; A limit switch that detects the opening / closing operation of the valve driving motor (MOV) in operation to drive or stop driving M0V, and a torque that mechanically stops valve driving when the limit switch is turned on or off. With switch, The current sensing unit detects the operating current of the valve drive motor and detects the voltage applied to the valve drive motor in order to identify various defects such as stub of the valve disc, physical damage of the stem and abnormal operation of the actuator. A motor applied voltage sensing unit for obtaining line voltage without phase change; A switch signal processing unit which senses the on / off state of the limit / torque switch and converts it into a low AC voltage of an insulated state and outputs the signal to the signal interface unit; A transducer for firstly amplifying the driving voltage signal and the driving current signal of the MOV, multiplying the phase-by-phase, synthesizing and secondly amplifying the power signal, and outputting a power signal to a signal interface unit; The card for the process control interface receives the voltage, current, and power signals output from the motor-applied voltage sensing unit, the current sensing unit, and the transducer, and the operation signals output from the other strain gauge processing unit, the LVDT, the load cell, and the limit switch, respectively. And a signal interface unit for converting an analog signal suitable for the input level of the signal, and converting the signal into a digital signal via the processing control interface card to perform data interfacing with the PC. The method according to claim 1, The current sensing unit is a performance diagnostic device of the valve in operation, characterized in that composed of first to third current sensors for sensing the current flowing in each phase (R, S, T) of the MOV. The method according to claim 1, The motor-applied voltage sensing unit is configured to convert a motor applied voltage applied to the primary side to a predetermined voltage on the secondary side to output a line voltage without a phase change in the YY connection. Device. The method according to claim 2, And a predetermined voltage at the secondary side of the transformer is converted to AC 110V for signal isolation. The method according to claim 1, The transducer may include first and second amplifiers for first amplifying signals for voltage and current, a multiplier for multiplying output signals of the first and second amplifiers phase by phase, and a three-phase output signal of the multiplier. And a third amplifier for amplifying the output signal of the synthesizer and outputting a power signal.