Encyclopædia Britannica, Ninth Edition/Electric Traction > 자유게시판

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Those utilizing one (or in some circumstances two) overhead conductors. Mr Field has proposed a tramway with two conduits, one beside every rail, containing two conductors, one to be charged positively and the opposite negatively, in order that a comparatively high resultant difference of potential is accessible for the motor although the potential of neither conductor differs to a dangerous diploma from that of the earth. Their plan is to make use of a effectively-insulated conductor in a closed channel underground. An advantage possessed by two motors is that, by coupling them in sequence or parallel, or by using one only, the driver is able to command completely different grades of energy without the usage of resistance coils. In comparing the 2 strategies, the loss which this entails must be set off in opposition to that which happens in the transmission system within the technique of conduction, an item which may be very small in favourable instances, but which turns into giant when there are various automobiles to be driven, when the line is lengthy, and when, owing to the usage of an exposed conductor, the electromotive drive must be stored low. The road is divided into short sections; each of these has an uncovered conductor, which could also be one of many rails, and this is placed in momentary contact with the insulated conductor as the train passes, by the pressure of the wheels on a versatile rail or stud, or by way of automatic electromagnetic switches.

Other trains at different locations in the line obtain the same current, every by breaking for the time the unusual contact between the 2 sections it touches, and substituting a contact by way of its own conductor and motor. Typically, the line is electrically divided into equal sections, which have the same length as a single practice, so that the front carriage is at all times on the section prematurely of the rear carriage. In vehicles pushed by storage batteries the identical object may be secured by numerous groupings of the cells. Soc. Arts, May 1884; also Professional Papers of the Corps of Royal Engineers, Chatham, vol. The conduit is positioned midway between the rails, however it may be questioned whether, in view of the situations of ordinary street site visitors, a greater place for it wouldn't be at one side. 1/2E. But this condition of maximum energy involves that half the power provided is wasted; to safe greater effectivity, motors are in follow run at a lot less than their most power, in order that e might strategy more nearly to equality with E. The sector magnets of motors, like those of dynamos, may be wound with coils in collection with the armature coil, or with coils forming a shunt to the armature, or with a mixture of both.

No control is exercised from the automobiles themselves; in fact, the trains run without attendants. In 1881 the late Prof. Fleeming Jenkin devised a system of electric locomotion wherein the autos are hung upon what resembles an exaggerated telegraph line. The telpher line is a steel rod or cable, suspended from brackets on posts about 70 toes apart; it serves without delay as service of weights and conductor of electricity. The practice is furnished with a steady conductor from finish to end, via which it makes electric contact between the section in front and the section behind, and the motor is included within the circuit of this conductor. See also The Electric Motor and its Applications, by T. C. Martin and J. Wetzler (New York, 1887). The Portrush line is described by E. Hopkinson and A. Siemens in a paper read earlier than the Society of Arts, April 1883. For telpherage, along with articles in the journals named, see Fleeming Jenkin, "On Telpherage," Jour.

A small electric motor, which hangs beneath the road and is geared by spur and chain gearing to a pair of driving-wheels, types the locomotive. Two methods of working are used, which enable trains to be run either in electrical collection or "parallel." Within the series system the successive sections of the road are electrically connected, so lengthy as no practice is on them, by the use of switches on the joints between the sections, in order that the whole types one continuous conductor. Telpherage.Telpherage.-In all of the methods of electrical traction to which reference has been made the highway on which the cars run is actually a railway or tramway of the sort utilized in horse traction and steam traction. The system of storage, by means of secondary batteries, has the nice benefit over the system of transmission via a conductor that it makes each automobile unbiased and that it's relevant to atypical tramway lines. When a train comes on anybody part it breaks contact on the joint between that section and the one behind it; the circuit, however, stays closed via the conductor on the practice itself, and in this manner the motor receives the present which is passing via the road.

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