像所有的电子产品一样。 Differential pressure transmitters are like all electronics. Electronic instruments are used for a certain period of time. Or due to improper maintenance and use. The internal components of the instrument, the electric deep transformer, etc. may appear aging, debt transformation, leakage, breakdown, open circuit or poor contact, etc. Im "will cause the performance of the instrument to decline and various failures. It must be repaired.
Overhauling the instrument is a technical task that requires the maintainer to have high theoretical and practical aspects. The inspector can neither rely on his face alone, nor can he rely on "talking on paper", let alone trying to get away with it by chance. Otherwise, you will gain nothing, even worse. We must do a good job of overhauling electronic instruments. Must have a certain theoretical knowledge of electrical and electronic circuits. And understand and master the structure, principle and correct use of the differential pressure transmitter instrument. In addition, # 8 certain facial repair procedures should be followed. Generally, the gun repair procedures for electronic instruments can be summarized as follows:
First, understand the situation
Repairing instruments is like a doctor seeing a patient. The first step is to understand the condition, that is, to understand the process and cause of the failure of the device before the manual maintenance of the instrument, and the performance of the failure. This is useful for analysis and troubleshooting. Second, observe the phenomenon, maintenance of electronic instruments must first start by observing the phenomenon of failure, the qualitative test and quantitative analysis of the differential pressure transmitter to be repaired, and then further observe and record the exact phenomenon and severity of the failure, which is to judge the nature of the failure It is very helpful and enlightening to the faulty part; for the fault phenomenon of burning fuses, flashovers, smoke, scorch, etc., you must be careful to prevent the fault from expanding and increase the difficulty of maintenance. 3. Surface inspection Surface inspection refers to Check without power on. Check method should be performed from the table and inside. First check the switches, knobs, dials, plugs, sockets, terminals, meters, and detectors of the panel of the instrument to be repaired for looseness, slippage, disconnection, and poor contact. If any abnormality is found, repair it immediately. Then open the cover of the instrument case, and check for abnormalities in the components of the internal circuit, whether the fuse is blown, and whether the internal connection screws have been loosened. Once abnormalities are found, they should be repaired before entering the surface. Power-on inspection procedures. 4. Understand and become familiar with the working principle After a preliminary surface inspection, you can further understand the overall working principle of the instrument; you should carefully read and study the technical information provided in the instrument manual—such as circuit structure, block diagram, and Electrical schematics, etc., in order to analyze the possible cause of the differential pressure transmitter failure, determine the circuit parts that need to be checked and the relevant data to be measured. This preparation work is done in a solid and meticulous manner, and it can play a more effective role in the maintenance work. 5. Test parameters. Based on the failure phenomenon of the electronic instrument and starting from the working principle of the instrument, the steps and methods for finding the cause of the failure and the tests that need to be tested are initially prepared. It is an important procedure in the maintenance work to make sure that the parameters are in mind. The test content mainly includes the waveforms, voltages, and overall indicators of the input and output points of each operating point. Remember to pay close attention to the abnormality of components when power is just applied. If abnormality is found, immediately turn off the power to avoid Expansion of the fault causes unnecessary losses. 6. Analyze the data, and further analyze the cause and location of the failure based on the test data, waveforms, and responses. Through repeated analysis and testing, determine the intact part and faulty part of the instrument, and then gradually narrow down the scope of the fault until the faulty components that are damaged, changed or soldered are found. This test and analysis procedure is the most critical and time-consuming part of the entire process of repairing electronic instruments, and it can reflect the theoretical level and practical ability of instrument maintenance personnel. 7. Implement repair. Based on the above analysis and reasoning, the fault location can be basically determined, and then the faulty component can be found, and the necessary selection, replacement, welding, adjustment, repair or repair of the component or fault point can be started. Copy and other repair work until the instrument returns to normal function. Because of the complexity of the failure, the above three procedures, Sections 5, 6, and 7, are sometimes successful in one go; but sometimes it may take multiple iterations, or even take detours, and experience multiple failures and setbacks to succeed. This is also a test of the will, ability, patience and care of maintenance personnel. In addition, pay attention to the rigorous process and firm welding when performing repairs to ensure that the instruments can work reliably for a long time and avoid adverse consequences such as recurrence of failures.
8. Verification after repair, qualitative test of the differential pressure transmitter after repair. First, roughly check whether the main function is restored and whether the function is complete. Under the premise of maintaining the main technical performance of the original instrument after trimming and updating, further quantitative testing should be performed in order to make necessary adjustments and calibrations, maintain the measurement accuracy that the instrument should have, and make the instrument recover the original performance index as much as possible .
研究GPS定位系统的设计背景和最初设计目的 Design background and original design purpose of GPS positioning system for differential pressure transmitter
Differential pressure transmitter research history found that during the 1991 Gulf War, the planes, tanks, and military vehicles of the Duochuan Army marched and attacked in the vast desert. Although there were no significant ground signs on the desert, the soldiers of the Multinational Force never Lost direction. This is because the multi-flash unit used the GPs system to enable the unit to accurately know its precise location, thus setting the foundation for the victory of the war. Students may also see Guan Guo's film "The Enemy of the Country". The black lawyers framed in the film can track him accurately regardless of where they fled. This is also the use of the GYPS system. The lawyer has a GPS micro receiver on him, which keeps him under satellite surveillance even when he is in motion.
The missing pilot who survived the crash of an airplane can rely on the GPS system and will be rescued soon. The differential pressure transmitter report shows that GPS has now been converted to civilian use, and taxis in Beijing and Shanghai have been equipped with GPS receivers. Once taxis are hijacked by drivers and the driver activates the alarm device, the public security agency can immediately The location and street of the hijacked taxi were found. From the thousands of cars driving on the street, the hijacked vehicle was quickly identified, rapid replacement forces were organized, gangsters were captured, and the driver was rescued.
In 1973, the U.S. Department of Defense organized the joint research, development, and establishment of a new generation of satellite navigation system plan. This is the so-called Navigation System Timing and Ranging / Global Positioning System (NAVRTAR / GPS). System (GPS) o
The GPS system is developed on the basis of a satellite meridian satellite navigation system, which is mainly composed of three parts: a space constellation part, a ground monitoring part, and a user receiving part.
According to the current differential pressure transmitter scheme, the space part of the global positioning system uses 18 satellites with a height of about 20200km to form a satellite constellation. The 18 satellites are distributed in six equally spaced orbits, and the angle between the orbital plane and the equatorial plane is 55 '(as shown in Figure 5-3). There are 3 satellites on each orbital plane, and the satellites are 120 'apart. The phase difference of the satellites on adjacent orbital planes is 40 ', that is, any satellite is northerly along its orbit by 40 * than the nearest satellite on its eastern orbiting plane. O The GPS satellite orbit is nearly circular, and the first phase is about 11h58mino.
Such a satellite distribution, except for a short time in individual regions, can guarantee that no less than 4 satellites are available for observation at any time in any region of the world. This provides continuous global navigation capabilities in time.
Since the launch of the first GPS experimental satellite in the United States in 1978, the system has been used for positioning research, development of experimental work, and rapid development. Due to the reasonable distribution of the number of GPS satellites (as listed in Table 5.1), which can cover any place in the world, at least 4 satellites can be continuously and simultaneously observed anywhere on the earth, thereby ensuring continuous three-dimensional global and global positioning. . The GPS global positioning system has multi-function and high accuracy to provide users with three-dimensional position, three-dimensional speed and time information.
车辆引行、导弹制导、精密定位、动态观测、设计安装、时间传递和速度测最等领域，而且对运动月标的监控和管理以及运动目标的报普、救援也获得了成功的应用。在测量方而，差压变送器推测这一定位技术在大地测及、工程测M、工程与地壳变形监测、地籍测_LS航空摄影测最、海洋测绘等领域发挥作用。 With the development of the PS system, GPS should be used for navigation of moving targets at sea, air, and land. Differential pressure transmitter vehicle guidance, missile guidance, precision positioning, dynamic observation, design and installation, time transmission. And speed measurement, etc., and the monitoring and management of moving moon targets, and reporting and rescue of moving targets have also been successfully applied. In terms of measurement, differential pressure transmitters speculate that this positioning technology is used in geodetic measurement, Engineering survey M, engineering and crustal deformation monitoring, cadastral survey_LS aerial photogrammetry, marine surveying and mapping play a role.