In electric cranes a useful method is to arrange the connexions so that the lifting motor acts as a dynamo, and, driven by the energy of the falling load, generates a current which is converted into heat by being passed through resistances.
In Squier and Crehore's " Synchronograph " system " sine waves of current, instead of sharp " makes and breaks," or sharp reversals, are employed for transmitting signals, the waves being produced by an alternating-current dynamo, and regulated by means of a perforated paper ribbon, as in the Wheatstone automatic system.
He found, as others have dune, that if a battery, dynamo or induction coil has its terminals connected to the earth at two distant places, a system of electric currents flows between these points through the crust of the earth.
Hence, by inserting a break-and-make key in the circuit of the battery, coil or dynamo, the uniform noise or hum in the telephone can be cut up into periods of long and short noises, which can be made to yield the signals of the Morse alphabet.
With " set" or " block" trains, that is, trains having their vehicles permanently coupled up, one dynamo may serve for the whole train, but usually a dynamo is provided for each coach, which is then an /..,F??
In most of the systems that have been proposed this result is attained by electrical regulation; in one, however, a mechanical method is adopted, the dynamo being so' hung that it allows the driving belt to slip when the speed of the axle exceeds a certain limit, the armature thus being rotated at an approximately constant speed.
The distinguishing feature of the first is the steepness of its outlines; this indicates that the induction increases rapidly in relation to the magnetic force, and hence the metal is well suited for the construction of dynamo magnets.
A very pure form of iron, which from the method of its manufacture is called " steel," is now extensively used for the construction of dynamo magnets; this metal sometimes contains not more than 0.3% of foreign substances, including carbon, and is magnetically superior to the best commercial wrought iron.
On the one hand he worked out the general theory of the magnetic circuit in the dynamo (in conjunction with his brother Edward), and the theory of alternating currents, and conducted a long series of observations on the phenomena attending magnetization in iron, nickel and the curious alloys of the two which can exist both in a magnetic and non-magnetic state at the same temperature.
As regards the generation of electric energy, by pointing out defects of design in the dynamo as it existed about 1878, and showing.
This rod was connected with the positive pole of the dynamo or electric generator.
This head slides freely in the cast iron tubes, and is connected by a copper rod with one of the terminals of the dynamo supplying the current.
For the theory and elemental laws of electro-deposition see Electrolysis; and for the construction and use of electric generators see Dynamo and Battery: Electric. The importance of the subject may be gauged by the fact that all the aluminium, magnesium, sodium, potassium, calcium carbide, carborundum and artificial graphite, now placed on the market, is made by electrical processes, and that the use of such processes for the refining of copper and silver, and in the manufacture of phosphorus, potassium chlorate and bleach, already pressing very heavily on the older non-electrical systems, is every year extending.
For this purpose the ohmmeter is provided with a small dynamo D, contained in a box, which produces a continuous electromotive force of from 200 to 500 volts when the handle of the instrument is steadily turned.
The shunt coil Sh and the series coil Se are connected together at one point, and the remaining terminals of the dynamo and shunt coil must be connected to a " good earth," which is generally the gas or water pipes w of the building.
On setting the dynamo in operation, a current passes through the shunt coil of the ohmmeter proportional to the voltage of the dynamo, and, if there is any sensible leakage through the insulator to earth, at the same time another current passes through the series coil proportional to the conductivity of the insulation of the wiring under the electromotive force used.
The tangent of the angle of deflection 0 of this needle measured from its position, when the shunt coil is disconnected, is equal to the ratio of the voltage of the dynamo to the current through the insulator.
If we call this last resistance R, the voltage of the working dynamo V, and the current through the insulator C, then tan 0 = C/V = R.
In this case the dynamo and ohmmeter are combined in one instrument.
The field magnet of the dynamo has two gaps in it.
The mass of mercury is thus set in motion owing to the tendency of a conductor conveying an electric current to move transversely across lines of magnetic force; it becomes in fact the armature of a simple form of dynamo, and rotates with a speed which increases with the strength of the current.
It takes the form of a small dynamo having an armature and field magnets without any iron core.
The massive graphite is very easily machined and is widely used for electrodes, dynamo brushes, lead pencils and the like.
Only the discovery of dynamo-electric machines and their application to metallurgical processes rendered it possible for E.
With the advent of the dynamo, the position of affairs was wholly changed.
The charge was reduced by means of a 50-volt current from a Soo-kilowatt dynamo, which was passed through the furnace for 12 hours till decomposition was complete.
The Heroult cell consists of a square iron or steel box lined with carbon rammed and baked into a solid mass; at the bottom is a cast-iron plate connected with the negative pole of the dynamo, but the actual working cathode is undoubtedly the layer of already reduced and molten metal that lies in the bath.
Of 70% has been obtained, and when a dynamo is driven directly by them about 66% of the hydraulic energy has been converted into electric energy.
In diameter) with the revolving part of the dynamo mounted on the upper end of the shaft weigh about 152,000 lb, a special device, since adopted in other similar power plants, was designed to balance in part this.
The first patents for the electrolysis of alkaline chlorides were taken out in 1851 and several others later on; but commercial success was utterly impossible until the invention of the dynamo machine allowed the production of the electric current at a sufficiently cheap rate.
The general principles of electrical engineering will be found in Electricity Supply, and further details respecting the generation and use of electrical power are given in such articles as Dynamo; Motors, Electric; Transformers; Accumulator; Power Transmission: Electric; Traction; Lighting: Electric; Electrochemistry and Electrometallurgy.
The third covers the period between 1831 and Clerk Maxwell's enunciation of the electromagnetic theory of light in 1865 and the invention of the self-exciting dynamo, which marks another great epoch in the development of the subject; and the fourth comprises the modern development of electric theory and of absolute quantitative measurements, and above all, of the applications of this knowledge in electrical engineering.
This important fact laid the foundation for all subsequent inventions which finally led to the production of electromagnetic or dynamo-electric machines.
On the technical side the invention of a new form of armature for dynamo electric machines by Z.
In 1873 at Vienna the fact was discovered that a dynamo machine of the Gramme type could also act as an electric motor and jwas set in rotation when a current was passed into it from another similar machine.
This invention in conjunction with an alternating current dynamo provided a new and simple form of electric arc lighting.
- Following on the discovery in 1873 of the reversible action of the dynamo and its use as a motor, efforts began to be made to apply this knowledge to transmission of power, and S.
Crompton, Elihu Thomson, Rudolf Eickemeyer, Thomas Parker and others, and the theory of the action of the dynamo had been closely studied by J.
Swinburne, and great improvements made in the alternating current dynamo by W.
Thus in twenty years from the invention of the Gramme dynamo, electrical engineering had developed from small beginnings into a vast industry.
But it was not until the dynamo was improved as a machine for generating large quantities of electricity at a very low cost that the electrolysis of copper could be practised on a commercial scale.
Two other courses of lectures were published in volume form, Dynamo-Electric Machinery (1882), and The Electro-magnet and Electromagnetic Mechanism (1891).