Electric Transmission of Energy, and Its Transformation, Subdivision, and Distribution: A Practical HandbookWhittaker & Company, 1890 - 348 Seiten |
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Seite 194 - Hence we should state more correctly that the most economical area of conductor is that for which the annual cost of energy wasted is equal to the annual interest on that portion of the capital outlay which can be considered to be proportional to the weight of metal used. "Prof. George Forbes, in his Cantor lectures on 'The Distribution of Electricity,' delivered at the Society of Arts, in 1885, called that portion of the capital outlay which.
Seite 160 - FIG. 5. a greater part of the revolution than before ; and if the governor balls come together, the speed of the motor being too small, the brush is moved in the opposite direction, so that it makes contact with B for a longer time during each revolution. If the motors are in series, we arrange that the periodic governor shunts the currents periodically, instead of introducing resistance. In this case the connections are as follows : — B is made of wood, while K is made of metal. K is connected...
Seite 193 - ... capital outlay is strictly proportional to the weight of metal contained in the conductor In practice this is however, seldom correct. If we have an underground cable, the cost of digging the trench and filling in again will be the same, whether the cross-sectional area of the cable be one-tenth of a square inch or one square inch: and other items, such as insulating material, are if not quite independent of the area, at least dependent in a lesser degree than assumed in the formula. In an overhead...
Seite 31 - We define, therefore, as the unit of electromotive force, that which is created in a conductor moving through a magnetic field at such a rate as to cut one unit line per second.
Seite 159 - A sample of an electro-motor governor of this type, and which may be called a "spasmodic governor," is shown (Fig. 4), and consists merely of a rotating mercury cup into which dips a wire, which makes in this case contact with the mercury, and so completes the circuit when the speed is slow, but which, on account of the hyperbolic form assumed by the surface of the mercury as the speed rises, ceases to dip into the mercury at high speeds, and so breaks contact. This governor, you observe, is very...
Seite 159 - ... motor is doing. Our periodic governor, then, differs from the spasmodic governor in the same way that a good loaded steam-engine governor differs from the ordinary governor of a gas-engine. One of the ways of effecting this result is as follows : — A brush, A, Fig. 5, lies on the rotating-piece, BK, the cylindric surface of which is formed of two conducting portions connected with one another through any resistance, and the brush, A, is moved along the cylinder, BK, under the action of the...
Seite 194 - Electricity,' delivered at the Society of Arts, in 1885, called that portion of the capital outlay which." is proportional to the weight of metal used, ' The Cost of Laying One Additional Ton of Copper,' and he showed that for a given rate of interest inclusive of depreciation, and a given cost of copper, the most economical section of the conductor is independent of the electromotive force and of tlic distance, and is proportional to the current.
Seite 159 - ... waste the excess power or store it up for future use. Hitherto the first method alone has been attempted, viz., that of cutting off the power, and usually with this very serious defect, that instead of the power cut off being directly in proportion to the work cut off, the arrangements have been such that either all power was cut off or none, so that the motion of the motor was spasmodic, just as in an ordinary gas-engine, which suffers from the same defects, that full charge of gas or no charge...
Seite 302 - ... (Fontaine), and the centrifugal pump to work ; but I failed to get the motor into action from the primary or secondary battery. This was a great disappointment, especially as it prevented my showing the reversibility of the Gramme machine. I was puzzled the whole of the evening and the whole of the night to find a means to accomplish my object, and it was only in the morning of the 3d of June, a few hours before the visit of the Emperor, that the idea struck me to work the small machine by means...
Seite 159 - periodic governor " the power is never cut off entirely for any length of time ; nor, on the other hand, is full power ever put on for any length of time, but in every revolution power is supplied during a portion of the revolution, the proportion of the time in every revolution during which much power is supplied to the time during which less is supplied depending on the amount...