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压力变送器工作原理【详解】

作者: 来源: 日期:2018-9-21 10:52:45 人气:132

压力变送器作为工业生产中最重要的一种钱汇娱乐,压力变送器在石油行业得到了广泛的应用,而且随着技术的发展,压力变送器的应用领域也越来越广阔。压力变送器可以实现对气体、液体等压力信号的转换,将其转换为4一20 mA的电流信号,二次仪表就可以进行测量、指示和调节。目前我国压力变送器的发展比较成熟,在长期的进口压力变送器的市场竞争下,国产压力变送器已经在各项功能及质量上媲美进口产品,并且在工业中取得了良好的应用效果,当然,产品的使用过程中难免会遇到小问题,所以昆山丹瑞认为对压力变送器的诊断和维护是一项重要的工作,只有正确使用和维护压力变送器才能确保设备的长期稳定运行。

1、压力变送器的工作原理        

压力变送器测量系统的安装包括三个部分,即导压管的敷设、电气信号电缆的敷设以及压力变送器的安装。在压力变送器工作过程中,通过隔离膜片和硅油将介质的压力传送给中心的测量膜片,双侧隔离膜片上会受到来自于双侧导压管的压差,在这里测量膜片发挥弹性元件的功能,在压差的作用下发生变形。测量膜片的位移和压差之间存在正比例关系,而且在膜片位移的影响下,差动电容器的电容量也会随之变化,测量电路将其转换为4一20 mA的直流电流信号。

2、压力变送器常见的故障类型         

压力变送器故障通常是由现场使用和安装方法不当造成的,例如变送器接线错误,电源电压不符合要求、充液管内清洁度不够、一次元件堵塞、指示表头与仪表接线端子接触不良等。   

变送器无输出         

当压力变送器无输出时,首先检查变送器电源接线是否正确,如果电源接线没有问题,接下来测量变送器的供电电源,是否有24 V直流电压,要求变压器电源电压最小12 V。如果变送器是带表头的,则先将表头的两根线短路,如果故障消失,则说明表头存在故障。   信号输出不稳定       

如果在压力不变的情况下,变送器输出信号值出现跳动现象,首选排除压力源的不稳定,之后检查钱汇娱乐自身震动是否正常,钱汇娱乐抗干扰能力是否满足要求,变压器是否存在间歇性短路或开路现象;检查各个稳压二极管、电路板焊接是否牢固、测试振荡频率是否稳定。       

最后,压力变送器在石油化工、工业自控环境等领域得到了普遍的应用,压力变送器的正确使用维护和故障诊断是确保压力变送器正常稳定工作的关键,这也是使用和维修人员必备的技能。压力变送器安装或使用不当极易出现故障,而且变送器经过长时间的使用后,电子元件和其他器件的性能都会发生变化,引发各种问题,变送器测量精度下降,会导致很大的安全隐患,因此研究变送器的故障诊断和维护是十分有必要的。在实际的诊断维修中,应结合变送器的实际情况以及环境情况,综合分析,全面排查。

As the most important sensor in industrial production, pressure transmitter has been widely used in petroleum industry, and with the development of technology, the application of pressure transmitter is becoming more and more extensive. The pressure transmitter can convert the pressure signals such as gas and liquid into a current signal of 4120 mA, and the secondary instrument can be measured, indicated and adjusted. Pressure transmitters in our country are relatively mature at present. In the long-term market competition of imported pressure transmitters, domestic pressure transmitters have been comparable to imported products in various functions and qualities, and have achieved good results in industry. Of course, the use of products will inevitably encounter small problems, so Kunshan Than Shwe believes that the diagnosis and maintenance of pressure transmitters is an important work, only the correct use and maintenance of pressure transmitters to ensure the long-term stable operation of equipment.

1. The working principle of pressure transmitter.

The installation of the pressure transmitter measuring system consists of three parts: the laying of the pressure guide pipe, the laying of the electric signal cable and the installation of the pressure transmitter. During the working process of pressure transmitter, the pressure of medium is transmitted to the measuring diaphragm in the center by isolating diaphragm and silicone oil, and the pressure difference from the two side pressure guide pipe will occur on the two side isolating diaphragm, where the measuring diaphragm exerts the function of elastic element and deforms under the action of pressure difference. There is a positive proportional relationship between the diaphragm displacement and the voltage difference, and under the influence of the diaphragm displacement, the capacitance of the differential capacitor will change accordingly. The measuring circuit converts it into a DC current signal of 4120 mA.

2. Common fault types of pressure transmitter

Pressure transmitter faults are usually caused by improper field use and installation methods, such as incorrect transmitter wiring, power supply voltage does not meet the requirements, the cleanliness of the filling tube is not enough, primary component blockage, indicating meter head and instrument terminal contact is not good.

Transmitter no output

When the pressure transmitter has no output, first check the power connection of the transmitter is correct, if the power connection is not a problem, then measure the power supply of the transmitter, whether there is 24 V DC voltage, the minimum voltage of the transformer power supply 12 V. If the transmitter is with the head, the two lines of the head of the meter will be short-circuited first, if the fault disappears, indicating that there is a fault in the head of the meter. Signal output instability

If the output signal value of the transmitter runs out when the pressure is constant, the unstable pressure source should be eliminated first, then the vibration of the sensor itself should be checked, the anti-jamming ability of the sensor should be satisfied, and whether the transformer has intermittent short circuit or open circuit phenomenon. Whether the welding is firm and whether the oscillating frequency is stable.

Finally, pressure transmitter has been widely used in petrochemical industry, industrial automatic control environment and other fields. Correct use, maintenance and fault diagnosis of pressure transmitter is the key to ensure the normal and stable operation of pressure transmitter, which is also a necessary skill for use and maintenance personnel. Pressure transmitter installation or improper use is very easy to fail, and after a long time of use, the performance of electronic components and other devices will change, causing a variety of problems, transmitter measurement accuracy will decline, will lead to great security risks, so the study of transmitter fault diagnosis and maintenance is very important. It is necessary. In the actual diagnosis and maintenance, should be combined with the actual situation of the transmitter and environmental conditions, comprehensive analysis, comprehensive investigation.

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