Energy, Power, And Work Evidence
Energy, Power, And Work
Section titled “Energy, Power, And Work”Evidence status: generated from processed OCR/PDF text. Treat each hit as a source-location aid until the passage is checked against the scan.
8735 hits
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15 sources
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315 sections
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What This Theme Gathers
Section titled “What This Theme Gathers”Passages involving energy, power, work, watts, losses, efficiency, power factor, stored energy, expenditure of power, and field energy.
Reading Layers
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Modern Reading Prompt
Use these hits to keep the engineering accounting visible: what is stored, dissipated, transmitted, transformed, or measured.
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Interpretive field readings should not erase Steinmetz’s explicit engineering accounting of power and energy.
Matched Aliases
Section titled “Matched Aliases”| Alias | Hits |
|---|---|
power | 4482 |
energy | 2060 |
efficiency | 719 |
loss | 687 |
power factor | 586 |
work | 276 |
losses | 270 |
watts | 177 |
stored energy | 169 |
watt | 64 |
expenditure of power | 8 |
energy of the field | 1 |
Source Distribution
Section titled “Source Distribution”Section Hits
Section titled “Section Hits”Representative Source-Located Passages
Section titled “Representative Source-Located Passages”Chapter 20: Single-Phase Commutator Motors - 167 hit(s)
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... urrent in the field circuit and so the field magnetism both reverse. Theoretically, a direct-current motor therefore could be operated on an alternating impressed e.m.f. provided that the magnetic circuit of the motor is laminated, so as to fol- low the alternations of magnetism without serious loss of power, and that precautions are taken to have the field reverse simul- taneously with the armature. If the reversal of field magnetism should occur later than the reversal of armature current, during the time after the armature current has reversed, but before the field has reversed, the mo ...... n the field circuit and so the field magnetism both reverse. Theoretically, a direct-current motor therefore could be operated on an alternating impressed e.m.f. provided that the magnetic circuit of the motor is laminated, so as to fol- low the alternations of magnetism without serious loss of power, and that precautions are taken to have the field reverse simul- taneously with the armature. If the reversal of field magnetism should occur later than the reversal of armature current, during the time after the armature current has reversed, but before the field has reversed, the motor torqu ...Chapter 3: Trigonometric Series - 163 hit(s)
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... rs as the starting-point of calculation of the phase of alternating currents. For instance, if a is the phase angle of a vector 98 ENGINEERING MATHEMATICS. quantity, tan a is given as the ratio of the vertical component over the horizontal component, or of the reactive component over the power component. In this case, if m . ,. . tan ex = a sin a = a and cos « = Va^ + h^ cot a = c "d' sin a = d and COS a = or, if Vc^+d^' Vc^+d^' (5c) The secant functions, and versed sine functions are so little used in engineering, that they are of interest ...... the curves an cos n6 and bn sin n6, which area gives as twice its average height the values Un and bn, as discussed in the preceding. In resolving an empirical periodic function into a trigono- metric series, just as in most engineering calculations, the niost important part is to arrange the work so as to derive the results expeditiously and rapidly, and at the same time accurately. By proceeding, for instance, immediately by the general method, equations (17) and (18), the work becomes so extensive as to be a serious waste of time, while by the system- atic resolution into simpler fun ...Lecture 17: Arc Lighting - 153 hit(s)
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... is consumed by the steadying resistance (or steadying reactance with alternating arcs) than high current arcs, or short arcs; and are therefore less economical on constant potential supply. Constant potential arc lamps are necessarily less efficient than constant current arc lamps, due to the power con- sumed in the steadying resistance. A large part of this power is saved in alternating constant potential arc lamps, by using reactance instead of resistance, but the power factor is there- fore greatly lowered ; that is, the constant potential alternating arc lamp rarely has a power facto ...... th alternating arcs) than high current arcs, or short arcs; and are therefore less economical on constant potential supply. Constant potential arc lamps are necessarily less efficient than constant current arc lamps, due to the power con- sumed in the steadying resistance. A large part of this power is saved in alternating constant potential arc lamps, by using reactance instead of resistance, but the power factor is there- fore greatly lowered ; that is, the constant potential alternating arc lamp rarely has a power factor of over 70%. Where therefore high potential constant current cir ...Chapter 4: Induction Motor With Secondary Excitation - 153 hit(s)
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... ng-current trans- former. As the alternating magnetizing current is a wattless reactive current, the result is, that the alternating-current input into the induction motor is always lagging, the more so, the larger a part of the total current is given by the magnetizing current. To secure good power-factor in an induction motor, the magnetizing current, that i«, the current which produces the magnetic field flux, must be kept as small as possible. This means as small an air gap between stator and rotor as mechanic- ally permissible, and as large a number of primary turns per pole, that is, as la ...... requirement of an exutMrVV momentary overload capacity has to be met, etc. In such motors of necessity the exciting current or current at no-load — which is practically all magnetizing current — is a very large part of full-load current, and while fair efficiencies may nevertheless be secured, power-factor and apparent efficiency necessarily are very low. As illustration is shown in Fig. 20 the load curve of a typical 100-hp. 60-cycle 80-polar induction motor (90 revolutions per minute) of the constants: Impressed voltage: ea = 500. Primary exciting admittance: Ya = 0.02 — 0.6 j. Primary s ...Chapter 16: Induction Motor - 143 hit(s)
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... R. 151. A specialization of the general alternating-current transformer is the induction motor. It differs from the stationary alternating-current transformer, which is also a specialization of the general transformer, in so far as in the stationary transformer only the transfer of electrical energy from primary to secondary is used, but not the mechanical force acting between the two, and therefore primary and secondary coils are held rigidly in position with regard to each other. In the induction motor, only the mechanical force between primary and secondary is used, but not the transf ...... secondary is used, but not the mechanical force acting between the two, and therefore primary and secondary coils are held rigidly in position with regard to each other. In the induction motor, only the mechanical force between primary and secondary is used, but not the transfer of electrical energy, and thus the secondary circuits closed upon themselves. Transformer and induction motor thus are the two limiting cases of the general alternating- current transformer. Hence the induction motor consists of a magnetic circuit interlinked with two electric circuits or sets of circuits, the pri ...Chapter 12: Frequency Converter Or General Alternating Current Transformer - 132 hit(s)
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CHAPTER XII FREQUENCY CONVERTER OR GENERAL ALTERNATING- CURRENT TRANSFORMER 103. In general, an alternating-current transformer conafete of a magnetic circuit, interlinked with two electric circuits or sets of electric circuits, the primary circuit, in which power, sup- plied by the impressed voltage, is consumed, and the secondary circuit, in which a corresponding amount of electric power is produced; or in other words, power is transferred through space, by magnetic energy, from primary to secondary circuit. This power finds its mechanical equivalent ...... , an alternating-current transformer conafete of a magnetic circuit, interlinked with two electric circuits or sets of electric circuits, the primary circuit, in which power, sup- plied by the impressed voltage, is consumed, and the secondary circuit, in which a corresponding amount of electric power is produced; or in other words, power is transferred through space, by magnetic energy, from primary to secondary circuit. This power finds its mechanical equivalent in a repulsive llirusi acting between primary and secondary conductors. Thus, if the secondary is not held rigidly, with regards ...Chapter 14: Constant-Potential Constant-Current Trans Formation - 129 hit(s)
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CHAPTER XIV CONSTANT-POTENTIAL CONSTANT-CURRENT TRANS- FORMATION 127. The generation of alternating-current electric power prac- tically always takes place at constant voltage. For some pur- poses, however, as for operating series arc circuits, and to a lim- ited extent also for electric furnaces, a constant, or approximately constant alternating current is required. While constant alter- nating-current arcs have ...... rd constant-voltage constant-cur- rent transformation are of considerable importance as a poffsiblo source of danger to the system. In a constant-current circuit, the load is taken off by short-circuiting, while opc;n-circuiting causes the voltage to rise to the maximum value pcjnnitted by the power of the generating source. Hence, whrjrrj the circuit constants, with a constant-voltage supply source, are Huch as U) approach constant-voltage constant-current tran.sfonnation, as in for instance the case in very long transmission line«, or>^;n-<:ircuit- ing may lead to dangeroiLs or even dest ...Chapter 24: Synchronous Motor - 127 hit(s)
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CHAPTER XXIV SYNCHRONOUS MOTOR 212. In the chapter on synchronizing alternators we have seen that when an alternator running in synchronism is connected with a system of given voltage, the work done by the alternator can be either positive or negative. In the latter case the alternator consumes electrical, and consequently produces mechanical, power; that is, runs as a synchronous motor, so that the investi- gation of the synchronous motor is already contained essentially in the equa ...... on synchronizing alternators we have seen that when an alternator running in synchronism is connected with a system of given voltage, the work done by the alternator can be either positive or negative. In the latter case the alternator consumes electrical, and consequently produces mechanical, power; that is, runs as a synchronous motor, so that the investi- gation of the synchronous motor is already contained essentially in the equations of parallel-running alternators. Since in the foregoing we have made use mostly of the sym- bolic method, we may in the following, as an example of the ...Lecture 8: Traveling Waves - 119 hit(s)
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LECTURE VIII. TRAVELING WAVES. 33. In a stationary oscillation of a circuit having uniformly distributed capacity and inductance, that is, the transient of a circuit storing energy in the dielectric and magnetic field, current and voltage are given by the expression i = ioe-"^ cos ((/> T CO — 7), ^ . . e = eoe~"' sin ((^ =F co — 7), where <j) is the time angle, co the distance angle, u the exponential decrement, or the "power-dissipation constant," and ^o and eo the ...... is, the transient of a circuit storing energy in the dielectric and magnetic field, current and voltage are given by the expression i = ioe-"^ cos ((/> T CO — 7), ^ . . e = eoe~"' sin ((^ =F co — 7), where <j) is the time angle, co the distance angle, u the exponential decrement, or the "power-dissipation constant," and ^o and eo the maximum current and voltage respectively. The power flow at any point of the circuit, that is, at any dis- tance angle co, and at any time t, that is, time angle 0, then is p = ei, = eo^e~2"* cos (0 =F co — 7) sin (0 =F co — 7), = ^6-^«'sin2(0Ta>-7 ...Lecture 8: Traveling Waves - 119 hit(s)
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LECTURE VIII. TRAVELING WAVES. 33. In a stationary oscillation of a circuit having uniformly distributed capacity and inductance, that is, the transient of a circuit storing energy in the dielectric and magnetic field, current and voltage are given ^by the expression i = iQe~ut cos (0 T co - 7), ) e = e0e~ut sin (</> T co — 7), ) where 0 is the time angle, co the distance angle, u the exponential decrement, or the "power-dissipation constant," and i0 and eQ the maximu ...... e, that is, the transient of a circuit storing energy in the dielectric and magnetic field, current and voltage are given ^by the expression i = iQe~ut cos (0 T co - 7), ) e = e0e~ut sin (</> T co — 7), ) where 0 is the time angle, co the distance angle, u the exponential decrement, or the "power-dissipation constant," and i0 and eQ the maximunl current and voltage respectively. The power flow at any point of the circuit, that is, at any dis- tance angle co, and at any time t, that is, time angle <£, then is p = ei, = e0ioe~2ut cos (</> T co — 7) sin (0 =F co — 7), = ^|V2«<sin2(c/ ...Lecture 5: Temperature Radiation - 116 hit(s)
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LECTURE V. TEMPERATURE RADIATION. 34. The most common method of producing radiation is by impressing heat energy upon a body and thereby raising its tem- perature. Up to a short time ago this was the only method avail- able for the production of artificial light. The temperature is raised by heating a body by the transformation of chemical energy, that is, by combustion, and in later years by the trans- ...... common method of producing radiation is by impressing heat energy upon a body and thereby raising its tem- perature. Up to a short time ago this was the only method avail- able for the production of artificial light. The temperature is raised by heating a body by the transformation of chemical energy, that is, by combustion, and in later years by the trans- formation of electric energy, as in the arc and incandescent lamp. With increasing temperature of a body the radiation from the body increases. Thus, also, the power which is required to main- tain the body at constant temperature incr ...Chapter 1: The Constants Of The Electric Circuit - 110 hit(s)
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CHAPTER I. THE CONSTANTS OF THE ELECTRIC CIRCUIT. 1. To transmit electric energy from one place where it is generated to another place where it is used, an electric cir- cuit is required, consisting of conductors which connect the point of generation with the point of utilization. When electric energy flows through a circuit, phenomena take place inside of the conductor a ...... ER I. THE CONSTANTS OF THE ELECTRIC CIRCUIT. 1. To transmit electric energy from one place where it is generated to another place where it is used, an electric cir- cuit is required, consisting of conductors which connect the point of generation with the point of utilization. When electric energy flows through a circuit, phenomena take place inside of the conductor as well as in the space out- side of the conductor. In the conductor, during the flow of electric energy through the circuit, electric energy is consumed continuously by being converted into heat. Along the circuit, from th ...Chapter 11: Foucault Or Eddy Currents - 105 hit(s)
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CHAPTER XI. FOUCAULT OR EDDY CURRENTS. 86. While magnetic hysteresis or molecular friction is a magnetic phenomenon, eddy currents are rather an elec- trical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cutting an electric conductor, the magnetic field induces a current therein. The M.M.F. of this current reacts upon and affects the magnetic field, more or less ; consequently, an alternati ...CHAPTER XI. FOUCAULT OR EDDY CURRENTS. 86. While magnetic hysteresis or molecular friction is a magnetic phenomenon, eddy currents are rather an elec- trical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cutting an electric conductor, the magnetic field induces a current therein. The M.M.F. of this current reacts upon and affects the magnetic field, more or less ; consequently, an alternating magneti ...Lecture 9: Oscillations Of The Compound Circuit - 100 hit(s)
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... transformer, line, load, etc. Oscillograms of such circuits have been shown in the previous lecture. If we have a circuit consisting of sections 1, 2, 3 . . . , of the respective lengths (in velocity measure) Xi, X2, X3 . . . , this entire circuit, when left to itself, gradually dissipates its stored energy by a transient. As function of the time, this transient must decrease at the same rate Uq throughout the entire circuit. Thus the time decrement of all the sections must be Every section, however, has a power-dissipation constant, Ui, U2, U3 . . . , which represents the rate at which the store ...... 3 . . . , this entire circuit, when left to itself, gradually dissipates its stored energy by a transient. As function of the time, this transient must decrease at the same rate Uq throughout the entire circuit. Thus the time decrement of all the sections must be Every section, however, has a power-dissipation constant, Ui, U2, U3 . . . , which represents the rate at which the stored energy of the section would be dissipated by the losses of power in the section, t , t , t ... But since as part of the whole circuit each section must die down at the same rate e~"o', in addition to its ...Lecture 9: Oscillations Of The Compound Circuit - 100 hit(s)
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... transformer, line, load, etc. Oscillograms of such circuits have been shown in the previous lecture. If we have a circuit consisting of sections 1, 2, 3 . . . , of the respective lengths (in velocity measure) Xi, X2, X3 . . . , this entire circuit, when left to itself, gradually dissipates its stored energy by a transient. As function of the time, this transient must decrease at the same rate u0 throughout the entire circuit. Thus the time decrement of all the sections must be 6-**. Every section, however, has a power-dissipation constant, u\t Uz, u3 . . . , which represents the rate at which t ...... , this entire circuit, when left to itself, gradually dissipates its stored energy by a transient. As function of the time, this transient must decrease at the same rate u0 throughout the entire circuit. Thus the time decrement of all the sections must be 6-**. Every section, however, has a power-dissipation constant, u\t Uz, u3 . . . , which represents the rate at which the stored energy of the section would be dissipated by the losses of power in the section, €-"»', €-«*', €-"*' . . . But since as part of the whole circuit each section must die down at the same rate e~Uot, in addi ...Mathematical Appendix 5: Appendix: Synchronous Operation - 99 hit(s)
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... e same frequency f, but are connected together while out of phase with each other by angle 2w. That is, the one alternator has the voltage phase (<f> to), the other the voltage phase (0+w). We may assume the alternators as of equal voltage, since a voltage difference superposes on the synchronizing energy current due to the phase difference, a reactive magnetizing current due to the voltage difference without materially changing the energy relations. The EMFs of the two alternators then may be represented by: ei = E cos (0 co) 1 e2 = Ecos (0+co) / (1) and the resultant voltage in the circuit between ...... e phase (<f> to), the other the voltage phase (0+w). We may assume the alternators as of equal voltage, since a voltage difference superposes on the synchronizing energy current due to the phase difference, a reactive magnetizing current due to the voltage difference without materially changing the energy relations. The EMFs of the two alternators then may be represented by: ei = E cos (0 co) 1 e2 = Ecos (0+co) / (1) and the resultant voltage in the circuit between the alternators then is : e = ei e 2 = E cos \ (<f> co) cos (</>+ co) [ = 2E sin co sin (2) and the interchange currentwbeteen the alter ...Apparatus Section 2: Induction Machines: Polyphase Induction Motor - 99 hit(s)
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... in so far as it differs from the typical polyphase machine. 2. CALCULATION 136. In the polyphase induction motor, Let Y = g — jb = primary exciting admittance, or admit- tance of the primary circuit with open secondary circuit; that is, ge = magnetic power current, be = wattless magnetizing current, where e = counter-generated e.m.f. of the motor; ZQ = r0 + jxQ = primary self -inductive impedance, and Zi = 7*1 + jxi = secondary self-inductive impedance, reduced to the primary by the ratio of turns.1 ...... pedance, and Zi = 7*1 + jxi = secondary self-inductive impedance, reduced to the primary by the ratio of turns.1 All these quantities refer to one primary circuit and one corre- sponding secondary circuit. Thus in a three-phase induction motor the total power, etc., is three times that of one circuit, in the quarter-phase motor with three-phase armature 1J^ of the three secondary circuits are to be considered as corresponding to each of the two primary circuits, etc. Let e = primary counter-generated e.m.f., or ...Chapter 11: Fouoault Or Eddy 0Ubbent8 - 98 hit(s)
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CHAPTER XI. FOUOAULT OR EDDY 0UBBENT8. • 86. While magnetic hysteresis or molecular friction is a magnetic phenomenon, eddy currents are rather an elec- trical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cutting an electric conductor, the magnetic field induces a current therein. The M.M.F. of this current reacts upon and affects the magnetic field, more or less ; consequently, an alternati ...CHAPTER XI. FOUOAULT OR EDDY 0UBBENT8. • 86. While magnetic hysteresis or molecular friction is a magnetic phenomenon, eddy currents are rather an elec- trical phenomenon. When iron passes through a magnetic field, a loss of energy is caused by hysteresis, which loss, however, does not react magnetically upon the field. When cutting an electric conductor, the magnetic field induces a current therein. The M.M.F. of this current reacts upon and affects the magnetic field, more or less ; consequently, an alternating magneti ...Lecture 6: Double-Energy Transients - 97 hit(s)
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LECTURE VI. DOUBLE-ENERGY TRANSIENTS. 24. In a circuit in which energy can be stored in one form only, the change in the stored energy which can take place as the result of a change of the circuit conditions is an increase or decrease. The transient can be separated from the permanent condition, and then always is the ...LECTURE VI. DOUBLE-ENERGY TRANSIENTS. 24. In a circuit in which energy can be stored in one form only, the change in the stored energy which can take place as the result of a change of the circuit conditions is an increase or decrease. The transient can be separated from the permanent condition, and then always is the representation of a gradual decrease of energy ...Lecture 6: Double-Energy Transients - 97 hit(s)
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LECTURE VI. DOUBLE-ENERGY TRANSIENTS. 24. In a circuit in which energy can be stored in one form only, the change in the stored energy which can take place as the result of a change of the circuit conditions is an increase or decrease. The transient can be separated from the permanent condition, and then always is the ...LECTURE VI. DOUBLE-ENERGY TRANSIENTS. 24. In a circuit in which energy can be stored in one form only, the change in the stored energy which can take place as the result of a change of the circuit conditions is an increase or decrease. The transient can be separated from the permanent condition, and then always is the representation of a gradual decrease of energy ...Chapter 14: Dielectric Losses - 90 hit(s)
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CHAPTER XIV DIELECTRIC LOSSES Dielectric Hysteresis 116. Just as magnetic hysteresis and eddy currents give a power component in the inductive reactance, as "effective resistance," so the energy losses in the dielectric lead to a power component in the condensive reactance, which may be repre- sented by an "effective re ...CHAPTER XIV DIELECTRIC LOSSES Dielectric Hysteresis 116. Just as magnetic hysteresis and eddy currents give a power component in the inductive reactance, as "effective resistance," so the energy losses in the dielectric lead to a power component in the condensive reactance, which may be repre- sented by an "effective resistance of dielectric losses" or an "effective conductance of dielectric losses." In th ...Lecture 3: Physiological Effects Of Radiation - 86 hit(s)
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... that the daylight reflected from the sky is about 100,000 times more intense than the light of the full moon. The organ by which we perceive the radiation, the human eye (Fig. 20), contains all the elements of a modern photographic camera — an achromatic lense: the lense L, of high refractive power, enclosed between the two transparent liquids A and B which correct the color dispersion, that is, give the achromatic property; a diaphragm: the iris 7, which allows the increase or decrease of the opening P, the pupil; a shutter: the eyelids and 87 38 RADIATION, LIGHT, AND ILLUMINATION ...... rkness, that is, the nerves of vision are rested and their sensitivity thus increased so as to per- ceive the much lower intensity of illumination. (3). By the logarithmic law of sensation. The impression made on our senses, eye, ear, etc., that is, the sensation, is not propor- tional to the energy which produces the sensation, that is, the PHYSIOLOGICAL EFFECTS OF RADIATION. 39 intensity of the light, the sound, etc., but is approximately proportional to its logarithm and the sensation, therefore, changes very much less than the intensity of light, etc., which causes the sensation. T ...Chapter 2: Long-Distance Transmission Line - 86 hit(s)
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... d themselves, and large currents and high e.m.fs. may be produced by small impulses, that is, low impressed alternating e.m.fs., or inversely, when once started, even with zero impressed e.m.f., such alternating currents traverse the lines for some time, gradually decreasing in intensity by the energy consumption in the conductor, and so fading out. The condition of this phenomenon of electrical resonance thus is that alternating impulses occur at time intervals equal to the time required for the impulse to travel the length of the line and back; that is, the time of one half wave of impre ...... he im- pressed frequency. For long-distance telephony the phenomena occurring in the line thus can be investigated only by consider- ing the complete equation of distributed capacity and inductance as so-called "wave transmission" and the phenomena thus essentially differ from those in a short energy transmission line. 4. Therefore in very long circuits, as in lines conveying alter- nating currents of high value at high potential over extremely long distances, by overhead conductors or underground cables, or with very feeble currents at extremely high frequency, such as telephone currents ...Lecture 12: Electric Railway - 85 hit(s)
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... mp- erature, and has a shorter life, than other electrical apparatus. The rating of a railway motor is therefore entirely determined by its heating. That is, the rating of a railway motor is that output which it can carry without its temperature exceeding the danger limit. The highest possible efficiency is therefore aimed at, not so much for the purpose of saving a few percent, of power, but because the power lost produces heat and so reduces the motor output. 3. Very variable demands in speed. That is, the motor must give a wide range of torque and speed at high efficiency. This excludes f ...... way motor is therefore entirely determined by its heating. That is, the rating of a railway motor is that output which it can carry without its temperature exceeding the danger limit. The highest possible efficiency is therefore aimed at, not so much for the purpose of saving a few percent, of power, but because the power lost produces heat and so reduces the motor output. 3. Very variable demands in speed. That is, the motor must give a wide range of torque and speed at high efficiency. This excludes from ordinary railway work the shunt motor and the induction motor. The power consume ...Lecture 1: Nature And Origin Of Transients - 82 hit(s)
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LECTURE I. NATURE AND ORIGIN OF TRANSIENTS. I. Electrical engineering deals with electric energy and its flow, that is, electric power. Two classes of phenomena are met: permanent and transient phenomena. To illustrate: Let G in Fig. 1 be a direct-current generator, which over a circuit A con- nects to a load L, as a number of lamps, etc. In the generator G, the line A, and the load L, a ...LECTURE I. NATURE AND ORIGIN OF TRANSIENTS. I. Electrical engineering deals with electric energy and its flow, that is, electric power. Two classes of phenomena are met: permanent and transient phenomena. To illustrate: Let G in Fig. 1 be a direct-current generator, which over a circuit A con- nects to a load L, as a number of lamps, etc. In the generator G, the line A, and the load L, a current i flows, and voltages e f . ...Lecture 1: Nature And Origin Of Transients - 82 hit(s)
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LECTURE I. NATURE AND ORIGIN OF TRANSIENTS. i. Electrical engineering deals with electric energy and its flow, that is, electric power. Two classes of phenomena are met: permanent and transient, phenomena. To illustrate: Let G in Fig. 1 be a direct-current generator, which over a circuit A con- nects to a load L, as a number of lamps, etc. In the generator G, the line A, and the load L, a ...LECTURE I. NATURE AND ORIGIN OF TRANSIENTS. i. Electrical engineering deals with electric energy and its flow, that is, electric power. Two classes of phenomena are met: permanent and transient, phenomena. To illustrate: Let G in Fig. 1 be a direct-current generator, which over a circuit A con- nects to a load L, as a number of lamps, etc. In the generator G, the line A, and the load L, a current i flows, and voltages e Fig ...Chapter 14: Phase Conversion And Single-Phase Generation - 82 hit(s)
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... ormers, be converted into any other polyphase system, and in such conversion, a balanced polyphase system remains balanced, while an unbalanced system converts into a polyphase system of the same balance factor.1 In the conversion between single-phase system and polyphase system, a storage of energy thus must take place, as the balance factor of the single-phase system is zero or negative, while that of the balanced polyphase system is unity. For such energy storage may be used capacity, or inductance, or momentum or a combination thereof: Energy storage by capacity, that is, in the diel ...... to a polyphase system of the same balance factor.1 In the conversion between single-phase system and polyphase system, a storage of energy thus must take place, as the balance factor of the single-phase system is zero or negative, while that of the balanced polyphase system is unity. For such energy storage may be used capacity, or inductance, or momentum or a combination thereof: Energy storage by capacity, that is, in the dielectric fu Id, required per kilovolt-ampere at 60 cycles about 200O <-.•■. ol space, at a cost of about $10. Inductance, that is. energy storage by the magnetic f ...Lecture 6: Luminescence - 76 hit(s)
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... into radiation of a different wave length. Usually luminescence at ordinary temperature, or at moderate temperatures, that is, temperatures below incandescence, is called fluorescence or phosphorescence. Fluorescence and Phosphorescence. Fluorescence is the production of radiation from the energy supplied to and absorbed by the fluorescent body, while phos- phorescence is the production of radiation from the energy stored in the phosphorescent body. This energy may be derived from internal changes in the body, as slow combustion, or may have been received by the body at some previous t ...... hat is, temperatures below incandescence, is called fluorescence or phosphorescence. Fluorescence and Phosphorescence. Fluorescence is the production of radiation from the energy supplied to and absorbed by the fluorescent body, while phos- phorescence is the production of radiation from the energy stored in the phosphorescent body. This energy may be derived from internal changes in the body, as slow combustion, or may have been received by the body at some previous time — as by exposure to light a calcium sulphide screen absorbs the energy of incident radiation, stores it in some form, ...Chapter 12: Effective Resistance And Reactance - 76 hit(s)
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... . This method gives what may be called the true ohmic resist- ance of the circuit. 2. By the ratio: Volts consumed in circuit Amperes in circuit In an alternating-current circuit, this method gives, not the resistance of the circuit, but the impedance, z = \/f^ + x^. 3. By the ratio: Power consumed, (Current) 2 where, however, the "power" does not include the work done by the circuit, and the counter e.m.fs. representing it, as, for instance, in the case of the counter e.m.f. of a motor. In alternating-current circuits, this value of resistance is the power coefficient of the ...... hmic resist- ance of the circuit. 2. By the ratio: Volts consumed in circuit Amperes in circuit In an alternating-current circuit, this method gives, not the resistance of the circuit, but the impedance, z = \/f^ + x^. 3. By the ratio: Power consumed, (Current) 2 where, however, the "power" does not include the work done by the circuit, and the counter e.m.fs. representing it, as, for instance, in the case of the counter e.m.f. of a motor. In alternating-current circuits, this value of resistance is the power coefficient of the e.m.f.. Power component of e.m.f. Total current ...Chapter 19: Synchronous Motor - 75 hit(s)
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CHAPTER XIX. SYNCHRONOUS MOTOR. 198. In the chapter on synchronizing alternators we have seen that when an alternator running in synchronism is connected with a system of given E.M.F., the work done by the alternator can be either positive or negative. In the latter case the alternator consumes electrical, and consequently produces mechanical, power ; that is, runs as a synchronous motor, so that the investigation of the synchronous motor is already contained essentially in the equa ...... on synchronizing alternators we have seen that when an alternator running in synchronism is connected with a system of given E.M.F., the work done by the alternator can be either positive or negative. In the latter case the alternator consumes electrical, and consequently produces mechanical, power ; that is, runs as a synchronous motor, so that the investigation of the synchronous motor is already contained essentially in the equations of parallel-running alternators. Since in the foregoing we have made use mostly of the symbolic method, we may in the following, as an instance of the ...