为什么英国/爱尔兰的插头里有保险管？-CAD家园

为什么英国/爱尔兰的插头里有保险管？

作者：cad 提交日期：2009-7-6| 分类: | 访问量：

为什么英国/爱尔兰的插头里有保险管？

为什么英国/爱尔兰的插头里有保险管？
英文如下,建议高手翻译一下：
Why does the United Kingdom/Ireland plug have a fuse?

The United Kingdom is the only country that requires a fused power plug. The British use a ring wiring system in their houses and buildings, which provides a secondary protection device at the plug, to minimize safety hazards. Circuits leave the local branch protection device, travel out to the loads (outlets or lamps, for example), and then return to the circuit protection device. In the Continental European and American systems, all wiring is done on a linear basis—a circuit leaves the circuit protection device and goes straight to the outlets or lighting circuits, that represent the load, as illustrated below.

In the British ring wiring system, a fault condition at an outlet, for example, will be sourced with current from both directions. This minimizes the amount of heat generated in the conductor, as the fault condition occurs, but before the circuit protection device can clear the fault. By minimizing the heat generated, the degradation of insulation (which accompanies overheating due to repeated fault conditions) is also diminished, improving the long-term safety of the insulation system.

Until the circuit protection device clears the fault, however, the fault condition is sourced from two different directions in the supply system. There is therefore a much greater potential fault current condition. The British feel that a secondary protection device at the plug minimizes the safety hazard this condition creates; hence, the power plug fuse.

The fuse installed in all British plugs conforms to BS 1362 ("General purpose fuse links for domestic and similar purposes…"). The size of this fuse is 6.3 x 25.4mm. It has a breaking capacity rating of 6000A and is constructed with a sand-filled ceramic tube. The time-current characteristic on this family of fuses is not necessarily consistent with any other international standard, but it appears to have most of the characteristics of a fast acting fuse. The British Standards Institution standard for fuses in general is BS 4265. *

本文摘自：http://www.jxcad.com.cn/read.php?tid=36938&fpage=210

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