Electric generator

“ The adaptation of an electric generator to storage-battery charging on a motor-car presented considerable difficulties, for the reason that the petrol motor runs at widely varying speeds, and that the voltage of the generator, therefore, tends to vary within wide limits, whereas a substantially constant voltage is needed for charging. Many systems of regulation were used with more or less success, but finally the socalled third brush system was adopted by a majority of the manufacturers of electrical equipment. ”

“ These transformers are employed in connection with alternating-current dynamos. Faraday not only gave to the world the first electric generator, but also the first transformer, and one of the first electric motors, and without these gifts the electric transmission of power over long distances, which has justly been regarded as one of the most marvellous achievements of our age, would have been an impossibility. ”

“ Thus, a one kilowatt plant permits the use of any one of these lamp circuit devices at a time, with a few lights in addition.
Power
Electric power is to be had through motors. A direct current dynamo and a direct current motor are identical in construction. That is, a motor becomes a generator if belted to power; and a generator becomes a motor, if connected to electric mains. ”

“ Now, when the Gramme machine was invented to supply currents of electricity under conditions much more favourable than the magneto-electric machines it superseded, and at a cost vastly less than that of any voltaic battery, it is highly improbable that the relation of the new current generator to the production of electro-motive power would long be overlooked. ”

“ Step-up transformers developing very high voltages are not an element of safety in a generator room, and the better practice is to locate them in a separate apartment by themselves, if not in a separate building. For the Niagara Falls plant, the transformers that deliver three-phase current at 22,000 volts are located in a building across the canal from the generating plant. ”

“ Transformers at the Niagara Falls station raise the voltage from 2,200 to 22,000 for the transmission to Buffalo.
As transformers can be wound for any desired ratio of voltages in their primary and secondary coils, a generator pressure that will allow the most economical construction can be selected where step-up transformers are employed. In general it may be said that the greater the capacity of each generator, the higher should be its voltage and that of the primary coils of step-up transformers, for economical construction. ”

“ If a generator and transmission line are so designed that the rise of voltage at the generator terminals just corresponds with the loss of voltage on the line when the output of that generator alone passes over it to some particular point, then the pressure at that point may be held nearly constant for all loads if no energy is drawn from the line elsewhere. These several conditions necessary to make regulation by the compounding of generators effective can seldom be met in practice. ”

“ We have seen how the simple glass cylinder or sulphur roll became, when rubbed, a generator of electricity. In a later chapter of electrical history, we saw a new and more powerful generator of electricity in the voltaic cell, by means of opposing metals acted upon chemically by acids. The greatest, grandest, most powerful, and most economic of all generators of electricity was yet to come in the shape of the dynamo. We see its beginnings in those investigations of Faraday which led to the discovery of the induction coil and the principles of magneto-electric induction. ”

“ The current for energizing the sending apparatus is taken from the lines of the Potomac Light and Power Company; this runs an electric motor of 200 horse power which in turn drives a 100 kilowatt alternating current generator; the current from the latter flows through a transformer which raises the pressure of it to 25,000 volts. Next a battery of compressed air condensers are charged with this high voltage current and this is discharged by a rotating spark-gap. ”

“ Motor-driven Sewing Machine
However, the convenience and cleanliness of electricity are fairly well known and appreciated, but the means by which electric currents may be generated economically, and by which this form of energy may be applied to bring about sufficient returns, financial and otherwise, to warrant the installation of an isolated plant for a farm or country home, are not so generally understood.
Electric current may be generated by means of a dynamo, or generator, with any kind of a power-producing plant. ”

“ Motors are rated by horsepower, and generators are rated by kilowatts. Thus a one kilowatt generator has a capacity of 1,000 watts; as a motor, it would be rated as 1000/746 horsepower, or 1.34 horsepower. Their efficiency varies with their size, ranging from 40 to 60 per cent in very small motors, and up to 95 per cent in very large ones. The following table may be taken as a guide in calculating the power required by motors, on 110-volt circuits:
[Pg 148]
An electric motor, in operation, actually generates electricity, which it pushes back into the line as a counter-electromotive-force. ”

“ In the rare case where the power to be developed is so great that the number of generators necessary to give security and reliability to the service leaves each generator with a capacity [106]
[107] larger than is desirable for structural reasons, the number must be increased simply to reduce the size of each generator. Such a state of facts existed at Niagara Falls, where the first station contains ten dynamos of 3,750 kilowatts each, and the second station contains eleven units of like capacity. ”

“ When mechanical power is employed for producing a current by means of a magneto-electric or dynamo-electric machine--or, to use a better expression, by means of a mechanical generator of electricity--it is necessary in reality to expend a greater quantity of power than i2R in order to make up for losses which result either from ordinary friction or from certain electro magnetic reactions which occur. The ratio of the quantity, i2R, to the power, W, actually expended per unit of time is called the efficiency of the generator. ”

“ In a comparison of floor areas per kilowatt of main generator capacities in electric stations using water- and those using steam-power, the matter of space for transformers may be entirely omitted, because the extent of this space is independent of the type or location of water-wheels, or the difference of water and steam as motive powers. Where water-wheels and their connected generators occupy separate rooms, as is often the case with turbines under low pressures, the wheel room has a little less length, and is generally narrower than the generator room. ”

“ At the Electra plant the generator capacity is 10,000 kilowatts, and the transmission to San Francisco is carried out over a single pole line that carries one circuit composed of three aluminum conductors, each with an area in cross section of 471,000 circular mils. From the generators at Cañon Ferry, which have an aggregate capacity of 7,500 kilowatts, a part of the energy goes to Helena over a separate line, and the transmission to Butte goes over two pole lines that are 40 feet apart. ”

“ If there is no electric lighting in the shop, it will be necessary to install a generator and a gas, gasoline, or steam engine, or a waterwheel to drive it. A 10 battery belt driven generator may be used in such a shop, and may also, of course, be used with a separate motor. The generator should, of course, be a direct current machine. The size of the generator will depend upon the average number of batteries to be charged, and the amount of money available. ”

“ With a constant speed at the motor and its connected generator it is of course easy to deliver current at constant voltage to the distribution lines. This constancy of speed makes the synchronous motor generator a favorite in large transmission systems with both power and lighting loads. The satisfactory lighting service in Buffalo, operated with energy transmitted from Niagara Falls, seems to be due in some measure to the use of synchronous motor generators at the sub-station in Buffalo, whence lighting circuits are supplied. ”

“ This station contains four three-phase generators of 750 kilowatts each, and six transformers of 500 kilowatts each, these latter being connected in two sets of three each. The use of three transformers for each three-phase generator instead of three transformers for each two or three generators, tends to keep transformers fully loaded when in use, and therefore to increase their efficiency. On the other hand, efficiency increases a little with the size of transformers, and the first cost per unit capacity is apt to be less the greater the size of each. ”

“ Electric generators are the points in a transmission system where the limit of practical voltage is first reached. In almost all high-voltage transmissions of the present day in the United States alternating generators are employed. Very few if any continuous-current dynamos with capacities in the hundreds of kilowatts and voltages above 4,000 have been built in Europe, and probably none in the United States. ”

“ He received only a portion of the current which passed. The major part of it passed across the gap at a, otherwise we should have noticed that the engine missed an explosion when he touched the binding post."
The only part of this electrical outfit from which one may receive a shock is that line from e to C. The greatest difference in electric pressure is always to be found between the two extremities of the [201] electric generator; as, for example, between the carbon end and the zinc end of the battery, the positive and negative poles of the dynamos ”

“ Except for a few little storage-battery or Diesel generator systems, that couldn't handle one tenth of one per cent of the barest minimum load, it's been the only source of electric current here since 1962, when the last coal-burning power plant was dismantled. ”

“ The larger sizes of transformers now in use have capacities equivalent to considerably over 1,000 horsepower. Some of these structures are employed at Niagara and others at Buffalo. As in the case of the apparatus just mentioned, the effort spent in the perfection of the huge dynamo-electric generators used in lighting and power stations has resulted in machines so perfect as to leave but little chance of further increase of effectiveness. They waste only a small percentage in converting mechanical power into electrical energy, and run for years with but little attention or need of repairs. ”

“ Where the electric generators operate at the maximum voltage of the system, as at Garvin’s Falls and in the power-house of the Manhattan Elevated Railway, there may be said to be only one general plan of connections possible. That is, the generators must connect directly with the main bus-bars at the voltage of the system, and the feeders or transmission lines must also connect to these same bars. ”

“ A more attractive system of control is to have the turbines drive electric generators and then use the electric power to drive the propellers through motors mounted on the propeller shafts. The electric power can easily be controlled from the bridge and the propellers may be reversed by reversing the motors. However, the disadvantage of the electric system is that it occupies a great deal of space, particularly in plants running over 100,000 horsepower. ”

“ All that the dynamo requires to enable it to produce electric current is power of some kind that may be applied in such manner and quantity as will cause the armature, or “interior core,” of the machine to rotate at a sufficiently high and uniform rate of speed. There are various kinds of power generators which will perform this work satisfactorily for isolated plants. ”

“ But you could focus a lot of it on a generator whose output voltage was jacked up, and charge capacitors with thousands of kilowatt-hours each. Generators everywhere could be made a lot smaller, because they wouldn't have to handle peak loads but only meet average demand. ”

“ In such cases, the excessive drop cannot be economically reduced by increasing the sizes of the line wire, while a sufficient increase of the voltage would cause serious variations under changes of load. Hence, it is common practice to employ some form of auxiliary generator or booster, which when connected in series with the feeder, automatically maintains the required pressure in the most remote districts so long as the main generators continue to furnish the normal or working voltage. ”

“ The surge of electrons along the length of the wire sets up a voltage difference across the ends of the wire. A generator uses this difference to convert the kinetic energy of the moving wire or armature into electrical energy. The wire is kept spinning by the shaft which is connected to a turbine driven by steam or water.
Let us try to eliminate the moving part, the generator armature. What we need is a moving conductor that has no shaft, no bearings, no wearing parts. The substance that meets these requirements is the plasma. ”

“ Dick, who had been invited to the "tryout," was full of questions as they sped silently, and with an absolute lack of vibration, along the road.
"How do you generate your electricity?" he asked eagerly.
"By a device geared to the rear axle," answered Tom. "It runs a sort of dynamo, though it would be difficult for you to understand it if I went into details. It's something like the ordinary generator and turns a constant stream of 'juice' into the storage batteries that, in turn, feed the engines." ”