Cyclopedia of Engineering: A General Reference Work on Steam Boilers, Pumps, Engines, and Turbines, Gas and Oil Engines, Automobiles, Marine and Locomotive Work Heating and Ventilating, Compressed Air, Refrigeration, Dynamos, Motors, Electric Wiring, Electric Lighting, Elevators, Etc, Том 7Louis Derr American school of correspondence, 1910 |
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CYCLOPEDIA OF ENGINEERING, Том 2 Louis 1868-1923 Derr,American Technical Society Попередній перегляд недоступний - 2016 |
Загальні терміни та фрази
alternating current alternating-current ammeter amount amperes Arc Lamp armature coils arranged battery bell belt branch circuit brushes CABLE calculation candle candle-power carbon CAUSE cent commutator conductors conduit connected constant-potential copper core counter-E.M.F. cut-out diagram direct current direct-current direction distribution curves dynamo effect efficiency electric electrodes Engineers feeders feet field magnetism filament flux flux-density foot-candles fuses gives heat illumination incandescent lamps inch increase induction installed insulation resistance iron light source load loss machine magnetic field Mechanical metal National Electric Code Nernst lamp neutral conductor obtained ohms operation outlet-box outlets parallel photometer placed pole pieces pulley reactance reduced reflectors REMEDY reversed revolutions per minute rheostat rotation screen shaft short circuit shown in Fig shows shunt motor sparking speed starting steel switch SYMPTOM TABLE tantalum terminals three-wire system tion torque transformer tube two-wire usually voltage voltmeter volts wattmeter watts winding
Популярні уривки
Сторінка 139 - It has been found that the best results are obtained when the tension in the driving side of the rope is only 3 to 4 per cent of the breaking strength.
Сторінка 264 - As a rule, the porcelain insulators should be placed not more than 4| feet apart; and if the wires are liable to be disturbed, the distance between supports should be shortened, particularly for small conductors. If the beams are so far apart that supports cannot be obtained every 4$ feet, it is necessary to provide a running board as shown in Fig. 24, to which the porcelain cleats and knobs can be fastened.
Сторінка 148 - The switch and rheostat must be located within sight of the motor, except in cases where special permission to locate them elsewhere is given, in writing, by the Inspection Department having jurisdiction.
Сторінка 369 - These do not differ greatly in construction from the direct-current arcs. When iron or other metal parts are used in the controlling mechanism, they must be laminated or so constructed as to keep down induced or eddy currents which might be set up in them. For this reason the metal spools, on which the solenoids are wound, are slotted at some point to prevent them from forming a closed secondary to the primary formed by the solenoid winding. On...
Сторінка 294 - From the table of reactances under the heading "18 inches," and corresponding to No. 0 wire, is obtained the constant .228. Bearing the instructions of the table in mind, the reactance-volts of this line are, 156.25 (amperes) X 10 (thousands of feet) X .228 = 356.3 volts, which is 17.8 per cent of the 2,000 volts to be delivered.
Сторінка 214 - ... there will not be more than two or three; and the particular one can be picked out by following the directions, which show how each case may be distinguished from any other. I. SPARKING AT THE COMMUTATOR. This is one of the most common of troubles, being often quite serious because it burns and cuts the commutator and brushes, at the same time producing heat that may spread to and injure the armature or bearings. Any machine having a commutator is liable to it, including practically all direct-current...
Сторінка 143 - The lower limit is specified for rubber-covered wires to prevent gradual deterioration of the high insulation by the heat of the wires, but not from fear of igniting the insulation. The question of drop is not taken into consideration in the above table.
Сторінка 223 - It is better to make observations for heating by starting with the whole machine cool, which is done by letting it stand for several hours. II. HEATING OF COMMUTATOR AND BRUSHES. CAUSE 1. Heat spread from another part of machine. SYMPTOM. Start with the machine cool, and run for a short time, so that heat will not have time to spread. The real seat of trouble is the part that heats first. REMEDY. (See Heating of Armature, Fields, and Bearings.) CAUSE 2. Sparking. Any of the causes of sparking will...
Сторінка 180 - ... to an accidental contact with some other wire or to a change of connections. Tools with insulated handles, or a dry stick of wood, should be used instead of the bare hand. The rule to use only one hand when handling dangerous electrical conductors or apparatus is a very good one, because it avoids the chance, which is very great, of making contacts with both hands and getting the full current right through the body. This rule is often made still more definite by saying, " Keep one hand in your...
Сторінка 295 - Therefore, for the problem taken, the drop is 18.7 per cent, and the loss is 16 . 1 per cent. If the problem be to find the size wire for a given drop, it must be solved by trial. Assume a size of wire and calculate the drop; the result in connection with the table will show the direction and extent of the change necessary in the size of wire to give the required drop. The effect of the line reactance in increasing the drop should be noted. If there were no reactance, the drop in the above example...