Electro-motors: a treatise on the means and apparatus employed in the transmission of electrical energy and its conversion into motive power: For the use of engineers and others |
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Common terms and phrases
accumulator acidulated water actuate advantage apparatus armature arranged assumed attached axis brass brushes Bunsen cell carbon cent charged circuit coal commutator conductor connected considerable construction copper core cost current of electricity cylinder Daniell cell deflection demagnetised diameter direct dynamo dynamo-electric machine effect electric current electric energy electric lighting electric railway electric source electrical resistance electro-magnet electro-motive force employed exciting coil extremities Faure field magnet flow foot-pounds heat helix horse power increase induced inductors insulated wire internal resistance interpolar layers lead length Lichterfelde locomotive magnetic field magnetised magneto-electric means mechanical metal motion motive power motor number of turns obtained passed permanent magnet placed polarity poles portion powerful currents produced proportional purpose rails repulsion reversed revolutions per minute ring rotation screw second machine Siemens soft iron speed steam engine steel surface tangent galvanometer train utilised velocity voltaic battery voltaic cell volts weber yield zinc
Popular passages
Page 45 - As resistance is directly proportional to the length, and inversely proportional to the area of the cross-section, the required resistance is R = 18.7 X ||||-X |= 10.5 ohms (approx.) Ans.
Page 120 - ... velocity of the train, until it exceeds that of the dynamo-electric machine, from which moment the functions of the two machines will be reversed ; the machine on the train will become a current generator, and pay back, as it were, its spare power into store, performing at the same time the useful action of a brake in checking further increase in the velocity of the train. If two trains should be placed upon the same pair of rails, the one moving upon an ascending portion, the other upon a descending...
Page i - ELECTRO-MOTORS. A Treatise on the Means and Apparatus employed in the Transmission of Electrical Energy and its Conversion into Motivepower. For the Use of Engineers and Others. By JW Urquhart, Electrician. Crown 8vo, cloth, pp. xii. and 178, illustrated. 1882. 7s. 6d. VAITANA SUTRA.
Page 123 - ... the old plan of concentrating the brake-power in two or three heavy brake vans placed in different parts of the train, and leaving the rest of the wheels without brakes. The advantage which thus evidently ensues from utilising the adhesion of every wheel of a train for the purpose of stopping a train suggests the further consideration as to whether it would not be a more scientific arrangement, as well as more economical in regard to the permanent way of railways, to utilise the adhesion of every...
Page 120 - ... machine is small, its potential of force is at its maximum, and it is owing to this favourable circumstance that the electric train starts with a remarkable degree of energy. With the increase of motion the accelerating power diminishes until it comes to zero, when the velocity of the magneto or driven machine becomes equal to that of the dynamo or current-producing machine. Between the two limits of rest and maximum velocity the driving power regulates itself according to the velocity of the...
Page 120 - FES, in two papers read by him recently before the Institution of Mechanical Engineers, so that it would be' superfluous for me to dwell upon this portion of the subject on the present occasion. Suffice it to say, that in transmitting the power of a stationary engine to a running train, the proportion of power actually transmitted varies with the resistance to, or speed of the train, reaching practically a maximum when the velocity of the machine on the train is about equal to two-thirds that of...
Page 120 - When descending, the speed of the magneto-electric machine will be increased, in consequence of the increased velocity of the train, until it exceeds that of the dynamo-electric machine, from which moment the functions of the two machines will be reversed ; the machine on the train will become a current generator, and pay back, as it were, its spare power into store, performing at the same time the useful action of a brake in checking further increase in the velocity of the train. If two trains...
Page 74 - It seems indeed very probable that a tramcar arranged to take in, say 7£ cwt. of freshly-charged accumulators, on leaving headquarters for an hour's run, may be driven more economically by the electric energy operating through a dynamo-electric machine than by horses. The question of economy between accumulators carried in the tramcar, as in M. Faure's proposal, and electricity transmitted by an insulated conductor, as in the electric railway at present being tried at Berlin by the Messrs Siemens,...
Page 119 - ... composing this train, the conductor riding on the first carriage, to which the form of a small locomotive engine has been given. Instead of the steam valve used in the latter, this engine is fitted with a commutator, by moving which the stopping, starting, and reversing of the engine can be effected. It is a remarkable circumstance in favour of the electric transmission of power, that while the motion of the electromagnetic or power receiving machine is small, its potential of force is at its...
Page 118 - When one dynamo machine is driven by another, the driven will generate a current in the opposite direction to that produced by the driving machine, from which consideration it is evident that the maximum power must be produced at a certain speed for the driven machine ; and by the author's calculation for two similar perfect machines this would be when the driven machine is running at one-third the speed of the other. By a perfect dynamo machine is understood one in which the mass of the iron is...