AD421在电力监控仪表中的应用

电力监控仪表是一种先进的智能化、数字化的前端采集元件,该类仪表已广泛应用于各种控制系统,它在功能上取代了测量仪表及常规电力变送器。以带有谐波监测功能的电力监控仪表作为设计对象,重点讨论了采用AD421实现4m A~20m A两线制电流变送的工作原理。采用32位飞思卡尔单片机MCF51AC256B作为系统CPU,出于安全考虑AD421与单片机之间的通信接口采用6N136进行光耦隔离,文中给出了4m A~20m A电流变送设计电路以及仪表系统硬件框图。通过实验,验证了电流环路中的给定电流输出稳定、准确,环路设计方案可行、可靠。

Application of AD421 in Electric Power Monitoring Instrument

Electric power monitoring instrument is an advanced intelligent and digital front-end capture devices which has been widely used in various control systems, it replaces the conventional power measuring instruments and transmitters in function. In this paper, power monitoring instrument with harmonic monitoring functions as a design object, focused on using AD421 to realize 4~20mA two-wire transmitter. System use 32-bit freescale chip MCF51AC256B as the CPU. For security reasons, communication interface between AD421 and CPU use 6N136 to execute optocoupler isolation, this paper presents the design of 4~20mA current loop and meter system hardware block diagram. Experiment verify the given current in current loop can be exported stably and accurately, loop design is feasible and reliable.