文档介绍：流量计微机检定系统的研究
摘要
流量计是一种工业中广泛应用的仪表,因其操作简便,测量精度高而深受用户欢迎。但是,流量计在经过一定时间使用之后必须进行检定,已确定其是否合格。传统上的检定是采用静态容积法靠手工操作,采用标准罐的读数与流量计水表的读数对比的方式进行检定,通过人眼识别读数和计算误差,因而存在检定精度低和效率低等问题。
根据现场的实际情况,本文提出一种基于标准表法和计算机测控技术的流量计的检定方法。分析了影响检定系统精度的主要因素为:标准表的精度、水流的稳定性和定时/计数的精度;设计了电磁流量计表头微弱信号的提取方案以及基于PC总线技术的高精度数据采集系统和输出控制硬件系统;采用PID控制策略通过变频器和电动调节阀实现对水流的稳定控制;采用Endress-Hauser Program53P(%)高精度电磁流量计作为标准表,提高了标准表的精度;运用windows 系统函数和Advantech相关函数实现了高精度和高稳定性的定时和计数处理。将数据采集、实时控制与标准检定规则相结合,运用Visual Basic 编写了软件,实现了对流量计水表的实时检定。
微机化流量计检定系统通过两年多的现场运行,实验结果表明达到项目所提出的各项性能指标,,取得较好的应用效果。从而实现流量计检定的自动化,提高了系统的可靠性与精度。
关键词流量计;数据采集;PID控制;信号处理;
Study puter based flow-meter test system
Abstract
As one of the measurement instrument, the flow-meter is generally used in the manufacturing process at present. Because of the convenient for use and a good precision, they are popularly used by user. However, the flow-meter had to be tested after used for a long time so that to insure they are eligible. Tradtionaly, the flow-meter was tested the method of the static volume by artificial operation, compare the reading of the standard volume to the reading of tested flow-meter by user eyes. This method will lead to not only low precision but also low efficiency.
In this paper aimed to this laggard condtions, the method which based puter detect and control technology has used to test the flow-meter. Analyzed the essential factors to improve the accuracy of test system were to improve the precision of the standard flow-meter, control the long stability of the flow and enhance the accuracy of the timer /counter. Design the scheme to pick-up the weak out-put signal of the tested ic flow-meter and the PC bus based hardware system of puter test system, take use of the pound control stratagem to control the stability of the flow, employ the Endress Hauser E+H promag53P high accuracy (%) ic flow-meter as a standard meter to improve the accuracy of the standard meter and use the windows function of the Advantech