Encyclopædia Britannica, Ninth Edition/Electric Traction

Those using one (or in some circumstances two) overhead conductors. Mr Field has proposed a tramway with two conduits, one beside each rail, containing two conductors, one to be charged positively and the other negatively, in order that a comparatively high resultant distinction of potential is available for the motor although the potential of neither conductor differs to a harmful degree from that of the earth. Their plan is to use a effectively-insulated conductor in a closed channel underground. An advantage possessed by two motors is that, by coupling them in collection or parallel, or by utilizing one solely, 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 involves has to be set off towards that which occurs within the transmission system in the strategy of conduction, an item which could also be very small in favourable cases, however which becomes large when there are numerous automobiles to be driven, when the line is lengthy, and when, owing to the use of an exposed conductor, the electromotive pressure needs to be kept low. The line is divided into brief sections; each of those has an exposed conductor, which may be one of the rails, and that is positioned in temporary contact with the insulated conductor because the train passes, by the pressure of the wheels on a versatile rail or stud, or by means of automatic electromagnetic switches.

Other trains at other locations in the road receive the identical current, every by breaking for the time the peculiar contact between the two sections it touches, and substituting a contact via its own conductor and motor. In general, the road is electrically divided into equal sections, which have the identical length as a single prepare, so that the entrance carriage is at all times on the section prematurely of the rear carriage. In cars pushed by storage batteries the same object may be secured by various groupings of the cells. Soc. Arts, May 1884; additionally Professional Papers of the Corps of Royal Engineers, Chatham, vol. The conduit is placed midway between the rails, but it surely may be questioned whether, in view of the circumstances of odd avenue site visitors, a better place for it wouldn't be at one aspect. 1/2E. But this situation of maximum power includes that half the energy equipped is wasted; to safe larger efficiency, motors are in observe run at a lot lower than their most energy, in order that e could approach extra practically to equality with E. The sphere magnets of motors, like those of dynamos, may be wound with coils in series with the armature coil, or with coils forming a shunt to the armature, or with a combination of both.

No control is exercised from the vehicles themselves; the truth is, the trains run with out attendants. In 1881 the late Prof. Fleeming Jenkin devised a system of electric locomotion during which 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 feet apart; it serves directly as carrier of weights and conductor of electricity. The prepare is furnished with a steady conductor from finish to end, through which it makes electric contact between the part in entrance and the section behind, and the motor is included in the circuit of this conductor. See additionally 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 learn earlier than the Society of Arts, April 1883. For telpherage, in addition to articles within the journals named, see Fleeming Jenkin, "On Telpherage," Jour.

A small electric motor, which hangs under the line and is geared by spur and chain gearing to a pair of driving-wheels, varieties the locomotive. Two techniques of working are used, which enable trains to be run either in electrical series or "parallel." In the series system the successive sections of the road are electrically connected, so long as no practice is on them, by the use of switches at the joints between the sections, in order that the entire kinds one continuous conductor. Telpherage.Telpherage.-In all of the methods of electrical traction to which reference has been made the road on which the automobiles run is actually a railway or tramway of the sort used in horse traction and steam traction. The system of storage, by way of secondary batteries, has the good benefit over the system of transmission by means of a conductor that it makes every automobile impartial and that it's relevant to unusual tramway lines. When a prepare comes on anyone part it breaks contact on the joint between that part and the one behind it; the circuit, nonetheless, stays closed by means of the conductor on the train itself, and in this manner the motor receives the present which is passing by means of the line.

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