城市轨道交通专业英语 课程教案(第16周3—4节)

城市轨道交通专业英语课程教案（第16周3—4节）授课题目

Unit 4 Power System and Electricity Equipment

Lesson 3 Overhead Catenary Traction System（下）授课类型

讲授型

教学目标Master the knowledge of all Sort (s) of Catenary Suspension Systems and pantographs

重点.All Sort (s) of Catenary Suspension Systems .pantographs

难点It can cause the dropper wires, from which the contact wire is hung, to " kink" and form little loops.

the dropper wires是宾语， from which the contact wire is hung 是介词短语，说明the dropper wires 的作用, to "kink" and form little loops是补语，进一步说明后果。

教学过程

结合课文以及教材中给出的图例，详细讲述文章中所描的高架链型牵引网系统中的各种形式的链型悬挂系统、受电弓等方面的相关知识以及文中生词、短语、及语法结构

作业1.New Words and Expressions

2. Notes on the text

主要教学内容2. All Sort (s) of Catenary Suspension Systems各种形式的链型悬挂系统

Various forms of catenary suspension are used (Fig. 4-14) , depending on the system, its age, its location and the speed of trains using it. 根据特定的系统、它的使用年限、使用区域以及使用列车的速度，各种形式的链形悬挂系统得到了应用（图4—14）。

Broadly speaking, the higher speeds, the more complex the "stitching" , although a simple catenary will usually suffice if the support posts are close enough on a high speed route.广而言之，速度越高，接触网越复杂，在一条高速线路上，如果支柱足够近，一个简单链型悬挂就能满足需要。

Modern installations often use the simple catenary , slightly sagged to provide a good contact.现代化的设备经常用简单链型悬挂，下垂度微小，可以提供良好的接触。

It has been found to perform well at speeds up to 200 km/h.已经发现，在速度高于200 km/h时，它也能很好地工作。

A tram depot may have just a single wire hung

directly from insulated supports. 一个有轨电车供电线仅有一条接触线，它直接悬挂在绝缘支持设备上。

As a pantograph passes along it, the wire can be seen to rise and fall.当受电弓通过它时，能够看到接触电线升起和落下。

This is all that is necessary in a slow speed depot environment.在低速环境下，它是足够的、满足要求的。

We haven't yet mentioned trolley poles as a method of current collection. 我们没有把电车电极作为一种受电方式。

These were used for current collection on low speed overhead systems and were common on trams or streetcars but they are now obsolete.这些一般应用在低速高架接触网系统，而且在有轨电车和路面电车中是常见的，但是现在它们是陈旧的技术。

DC overhead wires are usually thicker and, in extrem e load cases, double wires are used, as in Hong Kong Mass Transit's 1500 V DC supply system.高架接触线常常很粗，在特殊负载情况下，采用双接触线，香港市内公

交通1500V DC供电系统就是这样的。

Up to 3000 volts overhead is used by DC main line systems ( e. g. parts of France, Belgium and Italy) ,

but below 1500 volts, a third rail can be used.高达3000v 的高架接触线常常应用在直流干线系统（如法国、比利时和意大利的部分铁路），但是1500V 以下的直流系统，可以采用第三轨。

In operating terms, the third rail is awkward because of the greater risk of it being touched at ground level.在运行期间，第三轨比较笨拙，因为要冒着在地面上接触到它的危险。

It also means that, if trains are stopped, the current has to be turned off before Passengers can be allowed to wander the track. 也就意味着，如果列车停了下来，在允许乘客在轨道上徘徊之前，电流必须被切断为了100％的安全。

Third rail routes need special protection to be completely safe. 第三轨线路需要特殊的保护。

On the other hand, some people consider the overhead catenary system will produce a visual intrusion.另一方面，一些人认为高架接触网系统（产生）视觉的干扰。

Singapore, for example, has banned its use outside of tunnels.例如，新加坡已经禁止在隧道外使用高架系统。