外语教育网
您的位置:外语教育网 > 行业英语 > 机电英语 正文
  • 站内搜索:

开关和保险丝

2008-01-23 09:28

  An electric switch is often on a wall near the door of a room. Two wires lead to the lamp in the room. The switch is fixed in one of them. The switch can cause a break in this wire, and then the light goes. The switch can also join the two parts of the wire again, then we get a light.

  Switch can control many different things. Small switches control lamps and radio sets because these do not take a large current, larger switches control electric fires. Other switches can control electric motors.

  Good switches move quickly. They have to stop the current suddenly. If they move slowly, an electric spark appears. It jumps across the space between the two ends of the wire. This is unsafe and it heats the switch. Very big switches are sometimes placed in oil, Sparks do not easily jump through oil, and so the oil makes the switch safer.

  A large current makes a wire hot. If the wire is very thin, even a small current makes it hot. This happens in an electric lamp.

  The electric wires in a house are covered with some kind of insulation. No current can flow through the insulation, so the current can never flow straight from one wire to the other, but the insulation on old wires is often broken, then the copper of the two wires can touch. A large current may flow, and if this happens, the wires will get very hot. Then the house may catch fire.

  Fuses can stop this trouble. A fuse is only a thin wire which is easily melted. It is fixed in a fuse-holder(保险盒). The fuse-holder is made of some material which cannot burn. A large current makes the fuse hot and then it melts away. We say that the fuse "blows(保险丝烧断)". The wire is broken and no current can flow. So the house does not catch fire, but all the lights and electric fires go out because there is no current.

  When a fuse blows, something is wrong. We must find the fault first. Perhaps two wires are touching. We must cover them with new insulation of some kind. Then we must find the blown fuse and repair it. We put a new piece of fuse- wire in the holder. (Sometimes we can find the right fuse- holder because it is rather warm, but the others are cold.) If we do not repair the fault first, the new fuse will blow immediately.

  Some men get angry when a fuse blow. So they put a thick copper wire in the fuse-holder! Of course this does not easily melt; if the current rises suddenly, nothing stops it. The thick wire easily carries it. Then the wires of the house may get very hot and the house may catch fire. Some of the people in it may not be able to escape. They may lose their lives. So it is always best to use proper fuse-wire. This will keep everyone and everything in the house safe.

相关热词:英语 科技
行业英语辅导课程
李 健协和医科大学医学博士,美国国立卫生研究院博士后……详情>>
李健:医学英语网上辅导名师
高 云澳大利亚注册会计师协会会员,会计专业硕士……详情>>
高云:财会英语网上辅导名师
李文沛中国政法大学博士,师从著名法学家周忠海教授……详情>>
李文沛:法律英语网上辅导名师

  1、凡本网注明 “来源:外语教育网”的所有作品,版权均属外语教育网所有,未经本网授权不得转载、链接、转贴或以其他方式使用;已经本网授权的,应在授权范围内使用,且必须注明“来源:外语教育网”。违反上述声明者,本网将追究其法律责任。
  2、本网部分资料为网上搜集转载,均尽力标明作者和出处。对于本网刊载作品涉及版权等问题的,请作者与本网站联系,本网站核实确认后会尽快予以处理。本网转载之作品,并不意味着认同该作品的观点或真实性。如其他媒体、网站或个人转载使用,请与著作权人联系,并自负法律责任。
  3、联系方式
  编辑信箱:for68@chinaacc.com
  电话:010-82319999-2371