• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

It should be mentioned at this point that corrosion is always a factor to be considered in electric supply systems, particularly DC systems. Overhead catenary systems, called "catenary" from the curve formed by the supporting cable, have a complex geometry, nowadays usually designed by computer. However, it was also used on a number of main line railway systems, and still is in some parts of continental Europe, for example. 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. The wire length is usually between 1000 and 1500 metres long, depending on the temperature ranges. It can cause the dropper wires, from which the contact wire is hung, to "kink" and form little loops. The contact wire tension will be in the region of 2 tonnes. The Non-metallic sheathed cable is also called NM cables or non-metallic building wire cables. Power is delivered from the service Weather head to the building via the main feeder cables and wires. Apart from only requiring a simple control system for the motors, the smaller size of urban operations meant that trains were usually lighter and needed less power.

Here are other reasons to select the appropriate cable size. The wrong electrical cable size can be wasteful, and in some cases dangerous. Incorrect tension, combined with the wrong speed of a train, will cause the pantograph head to start bouncing. The Department of Energy was tasked with identifying the cause. Along the history, The evolution of cables has played a fundamental role in the advancement of communication and energy transmission. Funitels are known to use the most energy of all cable car systems and due to their dual loop configuration (which provide both support and propulsion) have higher maintenance costs. Broadly speaking, the higher speeds, the more complex the "stitching", although a simple catenary will usually suffice if the support posts are close enough together on a high speed route. The subsections can be joined through special high speed section switches. Figure 8: Insulated neutral section in an overhead line.

At the other end of the scale, a tram depot may have just a single wire hung directly from insulated supports. This was well understood in the late 19th Century and was one of the reasons why London’s Underground railways adopted a fully insulated DC system with a separate negative return rail as well as a positive rail - the four-rail system. This is why national electrical supplies are distributed at up to 765,000 volts AC . Electrical wires and cables are responsible for delivering electricity to the appliances and devices that we use every day. At present, almost everything is powered and operated by electricity due to the advancement in technology. This would be prohibited in Britain due to the inflexible safety approach there. Somewhere in town there is a telephone exchange, and somewhere in your house there is a telephone. The insulation of a telephone cable is composed of dry cellulose (in the form of paper tape wrapped around the conductor or paper pulp applied to the conductor) or of polyethylene. This pole supports electric power conductors, telephone conductors, a streetlight, and several pulleys. An electric arc occurs with each bounce and a pan and wire will soon both become worn through under such conditions.

The wire must be able to carry the current (several thousand amps), remain in line with the route, withstand wind (in Hong Kong typhoon winds can reach 200 km/h), extreme cold and heat and other hostile weather conditions. The layers in the cable allow the metal core to conduct electrical current securely in the location it is installed in. These cables use gas or oil to maintain the pressure of the cable above the atmosphere. There are different types of computer cables available in the market which are discussed below. Established in 1978, the company is better known for manufacturing wires and cables of high quality in the market. The French TGV (High Speed Train) formation has a power car at each end of the train but only runs with one pantograph raised under the high speed 25 kV AC lines. On lines equipped with AC overhead wires, special precautions are taken to reduce interference in communications cables. It is easier to boost the voltage of AC than that of DC, so it is easier to send more power over transmission lines with AC. The transmission of electromagnetic wave reflects in the core cladding.

When you loved this informative article and you would want to receive more information relating to what is electric cable kindly visit the website.