摘要
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。
Electric power monitoring instrument is an advanced intelligent and digital front-end capture devices which has been widely used in various control systems and replaced the conventional power measuring instruments and trans -mitters in function.In this paper, power monitoring instrument with harmonic monitoring functions is made as a design object, the working principle of using AD421 to realize 4mA^20mA two-wire transmitter is discussed .32-bit frees-cale chip MCF51 AC256 B is used as the CPU .For security reasons , communication interface between AD 421 and CPU uses 6N136 to execute optocoupler isolation .This paper presents the design of 4mA^20mA current loop and the hardware block diagram of the meter system .Experiments verify the given current in current loop can be exported stably and accurately , the loop design is feasible and reliable .
出处
《电测与仪表》
北大核心
2015年第9期24-29,共6页
Electrical Measurement & Instrumentation
关键词
变送器
光耦隔离
电流环
transmitter
optocoupler isolation
current loop
