CN203132763U - Pressure releasing valve verifying device - Google Patents

Abstract

The utility model relates to a calibration device for a pressure release valve, which includes a mechanical part and a control system, and is characterized in that the mechanical part includes an air pump, a pre-compressed air intake electromagnetic valve, an air capacity at a pre-compressed end and a pressure control electromagnetic valve , connect the pressure release valve to be verified with the pressure control solenoid valve, the pressure control solenoid valve is connected with the pre-compression intake solenoid valve through the pre-compression end gas capacity, and the pre-compression intake solenoid valve is connected with the air pump. The utility model can easily realize on-site verification (the mass of the whole set of devices is less than 10kg), and has a good effect on the rapid diagnosis of the pressure release valve failure and the determination of the action performance.

Description

A pressure relief valve calibration device

【Technical field】

The utility model relates to the technical field of pressure relief valves, in particular to a calibration device for pressure relief valves.

【Background technique】

The pressure relief valve is one of the important means for the internal fault protection of the transformer. With the increase of years, the aging of the components of the pressure relief valve, especially the spring, will affect the accuracy of the action of the pressure relief valve. However, after all the pressure relief valves are installed, they cannot be effectively repaired and calibrated due to the limitation of site conditions. At present, the calibration method of the pressure relief valve mainly adopts the method of suddenly releasing the impact after the gas pressure is stored. This method has a bulky calibration device (the mass of the entire device is greater than 300kg), and the calibration can only be completed in the laboratory. The calibration process is noisy and The energy consumption is high, and there are safety hazards due to high-pressure gas storage, and it is impossible to realize the on-site verification of the pressure relief valve.

【Content of utility model】

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a pressure relief valve calibration device.

The purpose of this utility model is achieved through the following technical solutions:

A pressure relief valve calibration device, which includes a mechanical part and a control system, is characterized in that the mechanical part includes an air pump, a pre-compressed air intake solenoid valve, a pre-compressed end gas capacity and a pressure control solenoid valve, and the The tested pressure relief valve is connected with the pressure control solenoid valve, the pressure control solenoid valve is connected with the pre-compression intake solenoid valve through the pre-compression terminal gas capacity, and the pre-compression intake solenoid valve is connected with the air pump.

The air volume at the preloading end is connected with the pressure sensor at the preloading end.

The gas capacity at the pre-compression end is connected with the pre-compression exhaust solenoid valve.

The pressure release valve to be checked is connected with the checked exhaust solenoid valve.

The components of the mechanical part are connected through a common interface.

The control system is composed of four parts, the first part is a calibration module, the second part is a pressure relief valve detection module, the third part is an air tightness detection module, the fourth part is a communication module, and the four modules communicate with the lower computer respectively. The program is connected.

The calibration modules are pre-pressure calibration and digital module calibration.

The pressure relief valve detection module is divided into three parts: pre-pressure control, pressure control, and reading action pressure value.

The air tightness detection module is divided into two parts: pressure control and pressure value upload.

The communication module is divided into two parts: 232 communication and SPI communication.

The modules of the control system are all mature technologies and can be purchased directly in the market.

Compared with prior art, the positive effect of the utility model is:

This calibration device, through quasi-static pressure process test verification and gas controllable pressure rate output, so as to achieve the same calibration purpose as the laboratory calibration device, and at the same time the gas storage pressure is small (gas storage pressure is less than 300kPa), passed The miniature pressure pump produces pressurized gas storage and the fast solenoid valve controls the output, making the power much smaller than that of the laboratory calibration device. Moreover, on-site verification can be easily realized (the mass of the whole set of devices is less than 10kg), and it has a good effect on the rapid diagnosis of pressure relief valve failure and the judgment of action performance.

【Description of drawings】

Fig. 1 is the principle structural diagram of the utility model.

Fig. 2 is a structural diagram of the control system of the utility model.

Figure 3 Schematic diagram of preload calibration;

Figure 4 digital module calibration block diagram;

Figure 5 Air tightness detection structure block diagram

Figure 6 Communication function structure block diagram

Figure 7 Rate Control Communication Event Driven Process

Figure 8 Functional flow of the rate control main program

Figure 9 Receive the detected pre-pressure value and set the communication event drive process

Figure 10 Receive the checked pre-pressure value and set the main program function operation flow

【Detailed ways】

The following provides a specific implementation of a pressure relief valve calibration device of the present invention.

Example 1

Please refer to attached drawings 1 and 2, a pressure relief valve calibration device, which includes an air pump, a preload intake solenoid valve, a preload end air capacity, a preload exhaust solenoid valve, a preload end pressure sensor, and a preload control Solenoid valve, PC, connect the pressure release valve to be calibrated with the pressure control solenoid valve through the universal interface, the pressure control solenoid valve is connected with the pre-compression intake solenoid valve through the gas capacity of the pre-compression end, and the pre-compression intake solenoid valve passes through The air pump is connected with the control unit of the PC.

The air volume at the preloading end is connected with the pressure sensor at the preloading end.

The gas capacity at the pre-compression end is connected with the pre-compression exhaust solenoid valve.

The pressure release valve to be checked is connected with the checked exhaust solenoid valve.

The pressure relief valve to be verified is connected with the control unit of the PC through a digital module.

A calibration method for a pressure release valve, the specific steps are:

(a) calibration,

Calibration is preload calibration and digital module calibration:

The pre-pressure calibration function measures the pressure value through the pressure sensor at the pre-pressure end. Before measuring the pressure value, in order to ensure the accuracy of the measured value, the pressure value needs to be calibrated. The process block diagram is shown in Figure 3 below; first open the tested The exhaust solenoid valve, the pressure control solenoid valve and the preload exhaust solenoid valve make the pressure sensor at the preload end directly communicate with the outside atmosphere. After stabilizing for a period of time, record the AD code of the sensor at the preload end as the AD code for zero point calibration. Then perform a full-scale calibration. Turn on the air pump, pre-press the intake solenoid valve, close the pre-press exhaust solenoid valve, open the pressure control solenoid valve, and close the checked exhaust solenoid valve. Measure the pressure value through the digital module. When the pressure value reaches 110kPa, close the air pump and the pre-compression intake solenoid valve; adjust the pressure value through the pre-compression exhaust solenoid valve. When the pressure value is stable at 100kPa, turn off the AD of the pre-compression end sensor The code is recorded as the AD code during full-scale calibration. Calculate the pressure value according to the current AD code, the zero point AD code and the AD code at 100kPa. Get the current pressure value.

Digital module calibration:

Digital module calibration includes zero point calibration and full scale calibration, as shown in Figure 4. The digital modules have been calibrated at the factory with a standard pressure source. During use, if the pressure value needs to be recalibrated, the digital module can be directly connected to a standard pressure source for calibration. When calibrating, connect the digital module to the atmosphere first, and send a zero point calibration command to the digital module after stabilization. After the digital module finishes processing the zero point calibration command, the single-chip microcomputer automatically sends a read pressure value command to the digital module, and the digital module returns the current pressure value. Adjust the pressure value of the standard pressure source to 0.25MPa, and send a full-scale calibration command to the digital module after it is stable. After the digital module processes the full-scale calibration command, the single-chip microcomputer automatically sends a read pressure value command to the digital module, and the digital module returns the current pressure. value. The digital module can restore the calibration parameters to the state at the time of delivery by restoring the factory setting command. The pressure value will be automatically uploaded about 10 seconds after the factory reset command is executed.

The microcontroller communicates with the digital module and ARM through the RS232 interface. Receive ARM's zero point calibration command and full scale calibration command according to the communication protocol, and transmit the command to the digital module according to the communication protocol of the digital module. After the digital module has processed the zero point calibration and full scale calibration commands, it will send a response frame to the single chip microcomputer for the completion of zero point calibration and full scale calibration. The pressure value read by the digital module is transmitted to the host computer through the single-chip microcomputer.

(2) Detection of pressure relief valve

Preload control:

The pressure measurement at the pre-compression end converts the pressure signal into an mv signal through the pre-compression pressure sensor, and sends it to the AD7714 chip in the form of a differential signal for AD conversion, converting the analog signal into a 24-bit digital signal. The sensor signal is amplified inside the AD chip by configuring the control word, and the magnification factor is 32. Then the AD value is converted into a pressure value through calculation. The measurement of the AD signal adopts the interrupt method. After the AD conversion is completed, an interrupt is applied to the single-chip microcomputer every 20ms, and the single-chip microcomputer responds to the interrupt and reads the AD code of the pressure value. The AD chip and the microcontroller use the same clock source.

In the process of pressure control, the rapid depressurization and slow depressurization of the pressure value are realized by controlling the duty ratio of the solenoid valve, and the pressure value is increased by the air pump. The duty cycle of the solenoid valve is adjusted according to the requirements of the pressure setting value to maintain the stability of the pressure value. In the step-down control process, when the difference between the pressure setting value and the pressure measurement value is large, the duty ratio of the solenoid valve is large. As the pressure measurement value is getting closer to the set value, the duty ratio of the solenoid valve becomes smaller. come smaller. When the pressure setpoint and pressure measurement are equal, the solenoid valve closes. In the boosting process, the pressure value is increased by controlling the air pump. In order to avoid the fluctuation of pressure value caused by the large flow rate of the air pump, the pre-pressure value is firstly set to be 10kPa higher than the set value during the boosting stage, and then the pressure value is fine-tuned during the depressurization process by adjusting the duty cycle of the solenoid valve.

Pressure control:

The speed is controlled by adjusting the duty cycle of the solenoid valve. In the process of pressure control, the single-chip microcomputer records the pressure value in real time with 10ms as the control cycle and measurement cycle, and in the way of data recursion, every time a new data is added, an old data is removed, and the data record of the array is updated, so that The pressure data value in the array is always the pressure value of the last 6 points. After the pressure relief valve operates, the pressure continues to decrease, and at this time the pressure is output slowly. If the pressure of the monitoring pressure relief valve increases, a detection process is completed, and the solenoid valve at the tested end is opened. The gas path of the pressure relief valve is directly connected to the atmosphere. Upload the opening pressure value and return pressure value at the same time.

(3) Air tightness testing:

In the process of air tightness testing, pre-pressure control is performed first. After the pressure value reaches the set value, the pre-pressure control is stopped. After the set time, record the initial pressure value, and then record the end pressure value after a period of time, and measure the air tightness of the tested end through the pressure leakage rate.

The air tightness testing process of the pressure relief valve is shown in Figure 5 above. Turn on the air pump, pre-press the intake solenoid valve, close the pre-press exhaust solenoid valve, open the pressure control solenoid valve, close the checked exhaust solenoid valve, and measure the pressure values of the pre-pressed end and the tested end through the digital module. When the pressure value is 10kPa higher than the pressure setting value, close the air pump and the pre-compression intake solenoid valve. The pressure is adjusted through the pre-compressed exhaust solenoid valve, so that the pressure value is close to the pressure setting value. After receiving the stop control instruction, stop controlling the pressure. The change of the pressure value of the digital module reflects the tightness of the air circuit.

(4) Realization of communication function

As shown in Figure 6 below, the communication function includes the communication between the lower computer and the upper computer, the communication between the lower computer and FPGA, the communication between the lower computer and the digital module; the communication between the lower computer and the upper computer is realized through the RS232 interface, and the communication between the lower computer and FPGA It is realized through SPI interface, and the communication between lower computer and digital module is realized through RS232 interface.

Pressure relief valve verification verification control procedure:

See Figure 7 for the rate control communication event-driven process.

The operating flow of the rate control main program function is shown in Figure 8.

See Figure 9 for the drive process of receiving the checked pre-pressure value and setting the communication event.

See Figure 10 for the operation flow of the main program for receiving the checked pre-pressure value and setting the main program.

Debugging and Verification of Calibration Device for Pressure Relief Valve

After the factory commissioning and acceptance of the pressure relief valve calibration device, the project team also conducted a large number of tests and researches in the laboratory to fully understand the characteristics of the device and the characteristics of the pressure relief valve, and also verified the reliability of the device. The specific methods and data are as follows:

Repeatability test:

The repeatability test of the device is to verify the consistency of the multiple measurement results of the device, which is the basic metrological characteristic of the device. The measurement method is to conduct multiple measurements on the same stable measured object, and the results meet the design technical indicators. This device has carried out 15 separate measurements on 2 pressure relief valves with different fixed values, and the results are shown in Tables 8 and 9 below (unit: kPa). After testing, it is verified that the repeatability of the device meets the design requirements.

Table 8 Repeatability Test-1

Standard deviation 0.616; mean 57.06

Table 9 Repeatability Test-2

Standard deviation 0.52; mean 81.9

Stability test:

The device stability test is to verify the long-term consistency of the device's measurement results and is also the basic metrological characteristic of the device. The measurement method is to perform multiple measurements on the same stable measured object within a period of time, and the results meet the design technical indicators. This device has carried out 5 separate measurements on 2 pressure relief valves with different fixed values within 2 months, and the results are as follows. After testing, it is verified that the stability of the device meets the design requirements.

Table 10 Stability Test Data-1

Standard deviation 0.48; mean 58.9

Table 11 Stability Test Data-2

Standard deviation 0.68; mean 81.7

The above is only a preferred embodiment of the present utility model, and it should be pointed out that for those of ordinary skill in the art, some improvements and modifications can also be made without departing from the concept of the present utility model. Should be regarded as within the protection scope of the present utility model.

Claims (10)

1. pressure relief valve calibration equipment, it comprises mechanical part and control system, it is characterized in that, described mechanical part comprises air pump, precompressed air inlet solenoid valve, pre-pressure side air-capacitor and electromagnetic pressure control valve link to each other pressure relief valve to be verified with electromagnetic pressure control valve, electromagnetic pressure control valve links to each other with precompressed air inlet solenoid valve by pre-pressure side air-capacitor, and precompressed air inlet solenoid valve links to each other with air pump.

2. a kind of pressure relief valve calibration equipment as claimed in claim 1 is characterized in that, described pre-pressure side air-capacitor links to each other with precompressed end pressure sensor.

3. a kind of pressure relief valve calibration equipment as claimed in claim 1 is characterized in that, described pre-pressure side air-capacitor links to each other with the precompressed exhaust solenoid valve.

4. a kind of pressure relief valve calibration equipment as claimed in claim 1 is characterized in that, described pressure relief valve to be verified links to each other with tested exhaust solenoid valve.

5. a kind of pressure relief valve calibration equipment as claimed in claim 1 is characterized in that, connects by general-purpose interface between each parts of described mechanical part.

6. a kind of pressure relief valve calibration equipment as claimed in claim 1, it is characterized in that, described control system is that four parts are formed, first is calibration module, second portion is the pressure relief valve detection module, third part is the impermeability detection module, and the 4th part is communication module, and four modules link to each other with program of lower computer respectively.

7. a kind of pressure relief valve calibration equipment as claimed in claim 6 is characterized in that, described calibration module is precompressed calibration and digital module calibration.

8. a kind of pressure relief valve calibration equipment as claimed in claim 6 is characterized in that, described pressure relief valve detection module is divided into pre-pressure-controlled, and operating pressure value three parts are read in pressure control.

9. a kind of pressure relief valve calibration equipment as claimed in claim 6 is characterized in that, described impermeability detection module is divided into pressure control and force value is uploaded two parts.

10. a kind of pressure relief valve calibration equipment as claimed in claim 6 is characterized in that, described communication module is divided into 232 communications and SPI communication two parts.

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