Pro Blend 600 Wax,Paraffin Wax Blend,Paraffin Soy Wax,Pro Blend 600 Blend Wax SHEN YANG XINGSHENG Wax Co.,Ltd , https://www.xswaxsupply.com
The paper introduces the principle of the drive signal, which is an intelligent positioner of DVC6000 series produced by Fisher, and its application in the field valve fault diagnosis is also introduced.
[Keywords] drive signal; DVC6000; fault diagnosis [Keywords] drive signal; DVC6000; fault diagnosis
ã€ä¸å›¾åˆ†ç±»å·ã€‘TH134 ã€Document code】A ã€Article number】1673-1069(2018)10-0158-03
1 Introduction DVC6000 series positioner can be installed on the straight stroke and angular stroke valve body of fisher and other manufacturers. It can be automatically verified, easy to operate, high control precision, stable regulation, less failure, and obtained in nuclear power plants. A wide range of applications. When the valve is online, the drive signal is read by HART, and the relevant parameters can quickly locate the fault of the valve. During the overhaul offline check valve, the valve body and the inside of the positioner can be diagnosed by the drive signal curve combined with the FS software. The problem was discovered and processed in advance, which greatly improved the stability of the operation of the power station.
2 DVC6000 positioner structure and principle DVC6000 series intelligent positioner adopts modular design, including IP, pneumatic amplifier (relay), PWB, valve position sensor and other modules. Due to the modular design, it is faulty and convenient for the site. replace.
The positioner control principle is shown in Figure 1. The positioner receives the 4~20mA command signal and sends it to the PWB board. After the microprocessor reads and calculates the PWB board, it converts it into the I/P drive signal, which is the drive signal. When the input signal increases, the drive signal sent to the I/P increases, the air pressure of the I/P output increases, and the pressure sent to the relay increases. The relay sends the amplified output to the bellows of the valve to open the valve. Or closed, and the position sensor will feedback the valve position signal to the PWB board to form a closed loop adjustment, so that the opening of the valve can be consistent with the command signal.
3 drive signal signal introduction 3.1 drive signal signal principle drive signal signal is the PWB board to send I / P drive signal, is the internal calculation parameters of the intelligent positioner, shown as a percentage signal, is the percentage of the maximum drive signal. As shown in Figure 2, the position of the pneumatic amplifier, the valve stroke feedback signal, and the input control signal are sent to the PWB board. After the operation is performed according to the tuning parameter set by the positioner, a drive signal is generated, and the position signal of the pneumatic amplifier is generated. A cylindrical magnetic block located inside is fed back to the PWB board, and the valve stroke signal is fed back to the PWB board through the valve position sensor. The small loop feedback gain, speed feedback gain, and pre-gain are set in the tuning, such as As shown in Table 1, you can select the parameters in the table, or you can choose the manual setting by the Expert user.
Table 2 shows the normal range of the drive siganl signal under each input signal. If the drive signal is out of the theoretical range when the valve is verified in the field or online, the positioner is abnormal. If the drive signal is low, it may be I/P abnormal or the nozzle is blocked; if the drive signal is high, it may be abnormal or leaking of the pneumatic amplifier;
3.2 drive signal acquisition signal signal can be read by HART or valvelink software and locator communication, HART / valvelink and locator communication using the hart communication protocol, the communication protocol uses FSK (frequency shift keying), respectively The 1200Hz and 2200Hz signals represent the digital signals "1" and "0". The average value of the HART signal is 0, which does not affect the control signal. Therefore, the drive signal can be read online.
For the positioner above AD, the drive signal curve can be drawn. As shown in Figure 3, the horizontal axis is the control signal (percentage) and the vertical axis is the drive signal. The curve drawing needs to place the positioner in out of service mode and use valvelink. The full stroke test is performed and the valve action is required during the full stroke test, so the full stroke test can only be performed during the offline calibration of the valve. For the HC version of the positioner without permission to perform a full stroke test, the drive signal curve cannot be drawn, but the drive signal value under the current signal can be read in the in service mode, and can be checked against Table 2 during valve verification.
3.3 Influencing factors of the drive signal According to Figure 2, the schematic diagram of the drive signal, the factors affecting the drive signal are: I / P, valve position sensor, pneumatic amplifier, PWB board, the adjustment parameter tuning setting inside the positioner, In addition, valve body problems such as jamming and jitter can also affect the drive signal curve.
Understand the factors affecting the drive signal. When the drive signal curve is abnormal during the valve calibration process, firstly, it is necessary to confirm that the mechanical body has no abnormality, and then check the positioner. In the nuclear power plant, the Flowscanner software is used to judge the state of the mechanical body. The flowscanner uses an external valve position and a pressure sensor to measure the data. Of course, the valve body can also be used to check the valve body status. However, when using the valvelink, the data is passed. Sensor acquisition inside the positioner, if the internal sensor of the positioner fails, it may not be able to correctly determine whether the valve body is faulty. The FS software is used to judge the valve body failure, and the valvelink is used to judge the positioner failure, which ensures the accuracy of the valve verification.
4 drive signal in the field application 4.1 valve can not be fully opened in the start-up phase of the unit overhaul, found that the condensate pump in the circulation valve in the control signal is 100%, the on-site inspection valve only about 70% of the opening, can not be fully opened, found After the fault, the valve is connected to the valve using the valvelink, and the parameters are read: input signal 20.95 mA, stroke setting value 100%, actual stroke 71.63%, drive signal: 100%, output pressure 2.57 bar, the above information is obtained, the drive siganl signal Normally, the output pressure has reached the supply pressure of the positioner, so that it can be judged that the positioner is working normally, and the valve cannot be fully opened. The valve may be stuck or the supply pressure is insufficient. The field slightly adjusts the supply pressure and the valve responds immediately. Later, it was confirmed that during the overhaul, the pressure of the valve was 2.44 bar when the valve was fully opened. After the system was online, the pressure of 2.57 bar was not enough to allow the valve to open completely. Therefore, the valve could not be fully opened or the supply pressure was insufficient, and the air supply was adjusted online. Pressure, the valve reaches the fully open position.
4.2 The valve does not move during the overhaul. The DVC6200 positioner is modified. During the start-up phase, the valve cannot be opened. The relevant information is read online. The pressure of the air source is 3.3 bar, the output of the positioner is 0 bar, the control signal is 7.61 mA, travel: 0%. , drive signal: 100%, through the above information, the valve is single-acting, the control signal at 7.61mA, the normal range of the drive signal signal should be 60% to 85%, at this time the drive signal is 100%, indicating that the positioner is faulty On-site measurement of the resistance of the I/P coil, to meet the requirements, on-site disassembly of I / P, found that there are obvious impurities on the surface of the I / P gas source hole, the air source hole is blocked, resulting in a large drive signal signal, the judgment is the valve Unable to open, after confirming the cause of the fault, the air source pipeline is purged. In order to prevent impurities from remaining inside the positioner, the positioner is replaced, and the operation is normal after the verification is passed.
4.3 During the abnormal overhaul of the drive signal curve, the main water supply regulating valve is verified. The valve uses the DVC6010 positioner. When the FS calibration tool is used to draw the dynamic characteristic curve of the valve, the valve works well and there is no jam. 5 (horizontal axis is valve valve position, vertical axis is valve cylinder pressure). When using valvelink for full stroke test, it is found that the drive signal signal has a significant sudden drop at about 60%, instead of continuous change, as shown in Figure 4, normal. The drive signal curve is shown in Figure 3. Through the curve of Fig. 4, it is judged that the valve moves smoothly without jamming and shaking phenomenon. The fault point is in the positioner, and the IP and pneumatic amplifiers are inspected on site. No abnormality is found. The drive signal under each signal platform is about 69%. According to the above analysis, It is judged that the valve position sensor may be abnormal. The positioner is replaced in the field and verified, and the drive signal curve returns to normal.
5 Conclusion The drive signal signal plays a very important role in the fault diagnosis of the intelligent positioner. For important regulating valves, such as the main water supply regulating valve and the exhaust bypass regulating valve, the drive signal curve is required during the overhaul calibration. Inspection, through the curve can find some potential problems, timely processing and troubleshooting, confirm the root cause of the failure, develop maintenance strategies, which will help to further improve the stability of equipment operation.
ã€Abstract】 This paper introduces the principle of the DVC6000 series intelligent positioner drive signal of Fisher manufacturer and its application in on-site valve fault diagnosis.