智能变压器温度控制器的设计本科毕业设计.doc

电力变压器是电力系统中的重要设备。当内部发生故障时,表现为三个线包温度升高。为了保护变压器,保障供电系统的安全,可靠运行,需要对变压器的三个线包温度进行监控,高压时报警,超温时跳闸。智能变压器温度控制器是以8位单片机AT89C51为核心,采用四个PT100传感器,并将其直接插入变压器线组包,对三相温度进行测量和控制,同时对环境温度进行测量和控制。最后将三相绕组温度转换成2-20mA变送信号输出。当风机有故障时,控制器还可以发出故障报警信号和保护信号,以确保变压器和其他设备的安全运行。AT89C51是在MCS-51单片机的基础上精心设计的最新型的高性能八位单片机。AT89C51是一种低损耗,高性能,CMOS八位微处理器,片内有4K字节的在线可重复编程快擦快写程度存储器。能重复写入/擦除1000万次,数据保存时间为十年。它的通信为串行通信,采用标准的RS-485接口技术。RS-485采用平衡式发送,差分式接收的数据收发器来驱动总线。相对于RS-232来讲,RS-485总线标准具有很多优点:支持多节点,远距离和接收高灵敏度等。本文主要讲述此种智能控制器的设计原理,工作流程,主程序以及RS-485的通信协议等。
关键词:温度控制,温度检测,AT89C51,RS-485标准总线
ABSTRACT
Electric power transformer is an important equipment in the electric power system. When having troubles , it shows that the temperature of the transformer , ensure the power supply's safe,and credibility processing, it needs control the transformer's three points high temperature, give a aptitude transformer and temperature controller's hard core is the signal chip AT89C51 which is 8-bit, use four sensors PT100,and put the sensors into the transformer's line groups, to control and measure the three points temperature and the environment temperature. At last it will be out with a kind of transformation signal, which is from 4mv to 20mv. When fans have malfunctions , controller can give trouble alarm signals and protect signals , to ensure transform and other equipment's safely working. AT89C51 is a SCM, which is short-wastage, high-powered . AT98C51 have a 4K-byte extent memorizer, which can write again in line, can lasered quickly , and write or erasure 1000 times. It can store date ten years . munication of this controller is serial and RS-485 interface technical. RS-485 use the transceiver , which is balance sent and difference receive. Compared with RS-232 , RS-485 has many advantages. Such as sustaining many nodes (32 nodes), long distance and incept higher delicacy, and so on. This paper will introduce the design principle, working precessor municate agreement of RS-485.
KEY WOEDS: temperat