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电器的定义-电器学的理论范畴

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概论

概述

本课程的主要理论范畴

电器技术的国内外现状

电器的定义和分类

典型电器的结构原理

§0-1  概 述

  • 本章教学目的与要求:

了解我国电器工业的现状及其发展前景;掌握电器的定义与分类、电器学的理论范畴,对典型电器的原理结构有一定的认识。

  • 本章教学重点与难点:

电器的定义;电器学的理论范畴

  • 本章教学基本内容

         1、什么是电器?如何分类?

         2、典型电器结构原理

         3、电器学的主要理论范畴

         4、我国电器工业现状及电器发展历史与展望

§ 0-2  本课程的主要理论范畴

电磁机构理论;电接触理论;电弧理论;发热和电动力理论

一、电磁机构理论

磁路与电磁铁特性。

特点:

电器电磁机构是有可动铁心和可变气隙的电磁装置,应用分析软件能正确计算电磁场的分布,由吸力与反力特性曲线关系将能确定电磁机构的形状和尺寸。

二、电接触理论

目的:触头设计

电接触理论包括:(1)电接触的物理化学过程中的热、电、磁以及金属变形等的效应;(2)接触电阻的物理化学本质及其计算;(3)接触或开断过程中,触头的腐蚀、磨损和金属迁移;(4)触头在闭合过程中振动磨损和熔焊。还包括电接触的结构形式、触头材料、加工工艺等。

三、电弧理论

(1)生弧的物理基础:电离和激励的概念,气体放电和击穿,火花放电、辉光放电和弧光放电的界定和过程等

(2)弧柱理论:包含离子平衡的物理化学状态;电弧的直径与温度分布;电弧的弧根和斑点;电弧等离子流;电弧电位梯度

(3)电弧的静伏安特性和动伏安特性;

(4)电弧过零时的介质恢复和电压恢复过程。

image.png、


四、发热和电动力理论

1.发热计算:发热损耗计算;交流电器因集肤效应和邻近效应产生的涡流和磁滞附加损耗导致的发热计算;电器在不同工作制下的发热计算;导电部件在大电流 下的发热计算,以及热稳定性校验。  

2.电动力计算:不同几何位置安置的导体间电动力的分析和计算。 

§0-3  电器技术的国内外现状

——我国的电器工业

  • 发展历程:仿苏→自己研发→引进、消化先进技术

  • 产业现状:三分天下(私营企业、国营企业、外企)

  • 课堂花絮:播放正泰、北开(厂长黄国诚为我校校友)、桂林电科所等若干企业的资料片。

  • 讨论:为何我国大部分电器产品质量不如国外产品?

§0-4  电器的定义和分类

一、电器的定义

凡根据外界指定信号和要求,自动或手动接通或断开电路,断续或连续地改变电路参数,以实现对电路或非电对象切换、控制、保护、检测、变换和调节用的电气设备,称为电器。

二、电器的分类

1、工作职能:手动、自动、起动调速、稳压与调压、测量放大与变换、牵引与传动;

2、结构工艺和生产部门:高压、低压、自动电磁元件、成套电器与自动化装置;

3、元件与使用系统的关系:电力网系统用、电拖系统用、自动化通讯用;

4、使用场合和工作条件:一般工业、特殊工况、农用、热带电器与高原电器、船用航空牵引用;

5、执行机能和转换深度:有触点、无触点和混合式电器等。

§0-5  典型电器的结构原理

一、继电器

  • 类型:电磁式与非电磁式(气囊式、受热等);

  • 名称: 电流继电器、电压继电器、热继电器、时间继电器、光继电器、压力继电器、速度继电器等。

  • 结构:感测元件、操动机构、辅助触头。

image.png

  • 特性

(1)继电特性:反映继电器的输出—输入关系的特性。可用右图表示。

            Xl是继电器的动作值

            XR是继电器的返回值

image.png


(2)吸合值与释放值;

(3)返回系数;

(4)动作灵敏度(规定负载下的最小动作功率);

(5)动作时间。

image.png

二、接触器

类型:直流接触器、交流接触器。

(1)直流接触器

主触头为单断点转动式,上装灭弧室;辅助触头随衔铁一同动作。线圈通电后,衔铁克服反力闭合;线圈断电,衔铁释放。

image.png

(2)交流接触器

作用:通断交流主电路,以三相为主,也有四相。

结构:线圈电源是交流或直流;形式上有转动式和直动式,右图为转动式。还有辅助触头和采用磁吹、窄缝和删片

等灭弧原理的灭弧室。

image.png

下图为直动式交流接触器。 其主触头是双断口,材料为银基合金。


image.png

(3)真空接触器

动静触头

真空泡

        真空介质

        电磁操动机构

image.png

三、各类接触器实物图

image.png

image.png

image.png

image.png

image.png


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首次发布时间:2026-04-16
最近编辑:5月前
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