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The point at which the cable is crushed or kinked is likely to heat up due to flow resistance, and a damaged sheath can expose the live cable and cause a short circuit. The tendency of return currents to wander away from the running rails into the ground can set up electrolysis with water pipes and similar metallics. The wheels, being steel, take it to the running rails. Of course, as many railways use the running rails for signalling circuits as well, special precautions have to be taken to protect them from interference. Of course, it needed a heavier transmission medium, a third rail or a thick wire, to carry the power and it lost a fair amount of voltage as the distance between supply connections increased. It can be summarised simply as AC for long distance and DC for short distance. This pack can be the perfect one. 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.

As AC is easier to transmit over long distances, it is an ideal medium for electric railways. 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. Since the current may have been switched off to stop an arc or because of a short circuit, it is important that the train does not connect the dead section to the live section by passing over the gap and allowing its busline to bridge the gap. An electric arc occurs with each bounce and a pan and wire will soon both become worn through under such conditions. Of course there are exceptions and we will see some of them later. At various points along the line, there will be places where trains can be temporarily isolated electrically from the supply system. Incorrect tension, combined with the wrong speed of a train, will cause the pantograph head to start bouncing. The wire is zigzagged relative to the centre line of the track to even the wear on the train's pantograph as it runs underneath. The contact wire has to be held in tension horizontally and pulled laterally to negotiate curves in the track.

Normally, each track is fed in each direction towards the next substation. This allows for some over supply and provides for continuity if one substation fails. The labeling of the electric cables is very significant because it provides information regarding the type of insulation used, the number of cables & the measure of the cables. However, it was also used on a number of main line railway systems, and still is in some parts of continental Europe, for example. A more common design is to include in the stranded cable assembly a number of high-strength, noncorrosive steel wires. Common violations include texting while driving, being distracted on the road or asleep at the wheel. A wire is designed with a single electrical conductor whereas an electrical cable is designed with several wires in a common sheathing but both of them are used to carry electrical current. The tension of the wire is maintained by weights suspended at each end of its length.

These are long and cylindrical in shape with a length of approximately two to four feet. This was overcome by placing substations at close intervals - every three or four kilometres at first, nowadays two or three on a 750 volt system - compared with every 20 kilometres or so for a 25 kV AC line. It doesn’t really matter whether you have AC or DC motors, nowadays either can work with an AC or DC supply. Overhead catenary systems, called "catenary" from the curve formed by the supporting cable, have a complex geometry, nowadays usually designed by computer. The same technique is used for DC or AC overhead line supplies. This is why national electrical supplies are distributed at up to 765,000 volts AC . Edmund King, AA president said: 'A perceived lack of charging points continues to be one of the top three reasons why drivers are hesitant to switch to electric cars.

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