【摘要】 电容式物位仪测量粘稠导电物位时,挂料产生的信号相位滞后真实信号相位π/4,对仪表测量精度有很大的影响。分析了电极挂料等效电路及其影响,研究了信号波形特点,提出在3π/4~7π/4处对测量信号进行斩波时域积分,可有效抵消挂料虚假信号对测量精度的影响,提高信噪比。设计了本安型二线制射频导纳物位仪,给出了硬件原理图及关键点信号波形图,建立了测试环境,使用标准云母电容对仪表进行标定,对数据进行线性拟合,以水为介质检验仪表的测量精度,实验证明仪表达到0.2级高精度设计要求。更多还原

【Abstract】 Attachment level signal lags π /4 phase behind true level signal when measurement of viscous conducting object,which has a great influence on measuring accuracy. In this paper,attachment level equivalent circuit and its effect are analyzed,and the characteristic of signal waveform is researched. The method of chopped wave and time domain integral phase shifting in 3π /4- 7π /4 is proposed to eliminate the attachment error of probe and improve SNR. The intrinsic safety type two-wire level gauge is designed. The hardware principle diagram and key point signal waveforms are given. The standard mica-capacitor is used to calibrate the instrument and test the accuracy of instrument by water. The instrument reaches the design requirement with 0. 2 level high precision.更多还原