Charles Steinmetz Electrical Disturbances the Nature of Electrical Energy 1912

8/2/2019 Charles Steinmetz Electrical Disturbances the Nature of Electrical Energy 1912

1/8

5ELECTRICAL DISTURBANCES AND THE NATURE

OF ELECTRICAL ENERGYBy CHARLES P. STEINMETZ

The distinction between electrical surges or waves of different formation arc first outlined and themanner in whieh such surges may affect the electric circuit illustrated by analogies between the action ofelectrical waves and the action of waves of the ocean. Light, heat, Hertzian waves and the field!' of alter-nating current systems are shown to be the same phenomenon, differing one from the other only in frequencyof vibration. Speculation is made as to what the electric wave is, leading to the contradictory deductionsthat for certain reasons the luminiferous ether must be considered as a gas of infinitely low density, and forcertain others as a solid. The ionic theory is next discussed. It is shown that attempts to prove thecorrectness of this theory lead to inconsistencies, and in certain cases to contradiction of some recognized lawof nature. The address is concluded with the statement that the same thing is true of all theories, whichdoes not mean that these theories are fundamentally wrong, but simply that our present formulations ofthem are far from final correctness and represent only crude conceptions of the nature of thinga+-Bnrroa.To all of us who are interested in the useof electric energy the nature and character-istics of electric energy are of importance;as on their understanding depends our

success in the economic use of this energy,and our ability of guarding against the diffi-culties, troubles and dangers which it maythreaten when out of control.The uses of electric energy are familiarto all of you, and form the subject of numerouspapers; the study of the troubles and dangersis in the hands of the Committee on HighPotential Disturbances, and therefore only ageneral discussion appears appropriate here.Electric energy is industrially used asdirect current and as alternating current,that is, as steady flow and as wave motion,usually of 25 or 60 cycles. Electric distur-bances are of various character, and, wherethey are periodic or wave motions, arc oftenof very high frequencies.I t can not well be doubted that electricdisturbances in our systems are increasingin number. The reason therefore is foundin the increasing size and energy of modernelectric systems., Just as in a pail of watereven a gale will not cause an appreciabledisturbance, or, as a small pond is usuallyquiet while the ocean is never at rest, butcontinually traversed by undulations fromsmall ripples to big waves, so in a smallisolated plant high voltage disturbances arepractically unknown; are rare in smallercentral stations; while in the huge modernsystems waves continuously traverse thecircuits, from minute high frequency ripplesof negligible energy to occasional high powersurges of destructive energy.The nature and form of disturbances metin electric systems are as variegated as those

An address to the Association of Edison Illuminating Com-panies at their convention in Spring Lake Beach, N, J, Pub-lished in the GENERAL ELECTRIC REVIEW by special permission,

of any other form of energy. Single electricwaves or impulses may appear as magneticdischarges, analogous to the snap of a whipin acoustics. Oscillations appear as waveswhich start suddenly and gradually die out,like the waves produced by throwing a stonein water; such arc the disturbances causedby switching, synchronizing, etc. Thenthere are travelling waves, analogous to theocean waves, of various size and wavelength; such for instance as the disturbancescaused by arcing grounds, by lightning, etc.Standing waves or stationary oscillations, likethose of a tuning fork or violin string, mayappear; and occasionally also, the mostdangerous of all disturbances, cumulativeoscillations, like the resonance of a tuningfork, namely, oscillations which graduallybuild up, increase in intensity until theyfinally limit themselves and become station-ary, 'or die down again, or increase untilsomething happens. Such for instance arethe hunting of synchronous machines, certaininternal transformer oscillations, etc.

Disturbances may affect the system bytheir quantity, or by their intensity, Electricpower can be resolved into the product of twoterms, quantity (or current) and intensity(or voltage), just as most other forms ofenergy are resolved into the product of twoterms. Hydraulic energy is quantity ofwater times head or pressure; heat energyis entropy times temperature, etc. Instancesof current disturbances are the momentaryshort circuit currents of alternators, the veryhigh frequency currents of arcing grounds,etc. Voltage disturbances appear whereveran electric wave breaksat a barrier in a circuit,as at a reactance, or in the end turns of atransformer.A wave in the water, as a big ocean wave,may cause damage by its bulk, by over-

Digitized byGoogle


2/8

6 GENERAL ELECTRIC REVIEWturning a structure. So a current wave maycause damage by its volume: the momentaryshort circuit current of an alternator maytear the windings to pieces, twist off theengine shaft, etc. Again, waves in the watertoo small of themselves to do any harm,may still do harm by the continuous pounding-by undermining and washing away theshore. In such manner a continuous oscil-lation-a continuous surge-may destroy.Each individual electric impulse would nothave sufficient energy to do damage, butwhen they follow each other successively,in thousands and millions, as coming froman arcing ground, then finally they causedestruction. Again, the damage may bedone by the pressure or voltage. Just likean ocean wave, not high enough in itselfto overtop the shore, when stopped at thebeach, when breaking in the surf, throwsthe water up to heights that are muchgreater than the height of the wave, soin the same manner a voltage impulse in anelectric distribution system, when it breaksat the entrance to another circuit, at areactance, or the end connections of thetransformer or generator, or the series coilof a potential regulator, may pile up highvoltage and rise to values far beyond thosewhich the wave has in its free path in thecable or the line; and there, at the pointwhere it breaks, where the wave is abruptlystopped by reactance, the voltage may riseto destructive values.

Disturbances may enter the electric systemfrom the outside, as by lightning; or theymay originate in the system, as by switching,synchronizing, etc.; or again, they mayoriginate in the circuit by outside inter-ference, as by an arcing ground, a sparkdischarge to an isolated conductor, etc.A characteristic of most of these distur-bances (which usually are comprised by thename of transients) is that they easily passfrom circuit to circuit across space by mag-netic or static induction, but frequentlydo not travel along the circuit for anyconsiderable distance. The cause thereofis found in their nature, particularly thefrequency.When an electric current passes througha circuit, there is in the space surroundingthe conductor which carries the currentan electric field: lines of magnetic forcesurround the conductor, and lines of electro-static or dielectric force radiate from theconductor. In a direct current circuit,if the current is continuous, the field is

constant; there is a condition of stress in thespace surrounding the conductor, which repre-sents stored enegy, magnetic energy anddielectric energy, just as a compressd springor a moving mass represents stored energy.In an alternating current circuit, the electricfield also alternates; that is, with every halfwave of current and of voltage, the magneticand the dielectric field start at the conductor,and run out from the conductor into spacewith the velocity of light, or 188,000 milesper second. Where this alternating field ofthe conductor, this electric wave, impingeson another conductor, a voltage and acurrent are induced therein. The inductionis proportional to the intensity of the field(the current and voltage in the conductorwhich produce the field) and to the frequency.Thus, where the frequency is extremely high,intense induction occurs; that is, considerableenergy is transferred from the conductorwhich produces the electric wave (the primaryor sending conductor) to any conductor onwhich the wave impinges (the secondary orreceiving conductor). The result is, that alarge part of the energy of the primaryconductor passes inductively across spaceinto secondary conductors, and the energydecreases rapidly along the primary conduc-tor. In other words, such a high frequencycurrent does not pass for long distancesalong a conductor, but rapidly transfers itsenergy by induction to adjacent conductors.This higher induction, resulting from thehigher frequency, is the explanation of theapparent difference in the propagation of highfrequency disturbances from the propagationof the low frequency power of our alternatingcurrent systems: the higher the frequency,the more preponderant become the inductiveeffects, which transfer energy from circuitto circuit across space, and therefore the morerapidly the energy decreases and the currentdies out along the circuit; that is, the morelocal is the phenomenon.The flow of electric power thus comprisesphenomena inside of the conductor, viz.,the dissipation of electric energy by theresistance of the conductor through itsconversion into heat; and phenomena in thespace outside of the conductor-the electricfield-which, in a continuous current circuit,is a condition of steady magnetic and diclec-tric stress, and in an alternating currentcircuit is alternating, that is, an electric waveissuing from the conductor and travelingthrough space with the velocity of light.In electric power transmission and distri-

Digitized byGoogle


3/8

ELECTRICAL DISTURBANCESbution, the phenomena inside of the conductorare of main importance, and the electricfield of the conductor is usually observed onlyincidentally, when it gives trouble by induc-tion in telephone circuits, or when it reachessuch high intensities as to puncture insulation,cause mechanical motion, etc. Inversely,in the use of electric power for wirelesstelegraphy and telephony, it is only the elec-tric field of the conductor, the electric wave,which is of importance in transmitting themessage; the phenomena in the conductor,the current in the sending antenna, are notused.The electric waves of commercial alternat-ing current circuits usually have the fre-quencies of 25 and 60 cycles. With a velocityof propagation of 188,000 miles per second,2,5 waves per second give a wave length of]882~00 =7500 miles. The distance to whichthe field of a transmission line extends is,therefore, only an insignificant part of thewave length, and the phase difference withinthe field of the transmission line thus isinappreciable. With the alternating fields oftransmission lines, the effect of the velocityof propagation of the field is thereforenegligible and is always neglected. Not sowith the alternating field of a wireless tele-graph station. Using frequencies from onehundred thousand to a million cycles, the

1 h f ]88,000 18 '1wave engt 1S rom l U - O , ( ) ( ) O =. mi es to188,000 -"l b fiW { ) - O O O _ 0.188 mt es, or a out 1000 eet., ,

With a wave length of from 1000 feet to2 miles, the electric wave extends overhundreds of cycles within the operativeradius of a wireless telegraph station, whichmav be hundreds or even thousands of miles.It is appreciable also in long distance tele-phone lines. The average frequency of thesound waves-;")OO cycles-gives a wavelength of :~76miles, and a 1000 mile telephoneline thus comprises over 2Y2waves. That is,at the moment when one half cycle of tele-phone current arrives in Chicago fromNew York, five succeeding half waves havealreadv left the New York terminal and areon the' wav.

Abnormal electric waves in industrialelectric power circuits vary from a few cyclesper second (in the stationary oscillations ofcompound electric circuits) up to thousands,hundreds of thousands and millions of cyclesper second. At frequencies of many thousand

7cycles per second, the ordinary measuringinstruments, the oscillograph, etc., fail torecord the wave; but such very high frequencywaves can still be observed and measuredthrough their inductive effects by bringinga conductor near them: the electric wave,impinging on this exploring conductor ("reson-ator" or "receiving antenna") then inducesa current in it, and this is observed by asufficiently delicate apparatus. In this man-ner, the telephone disturbances caused byalternating electric railway circuits have beenstudied by exploring antennae. A veryintense wave, at short distance from itsorigin, may be observed by the spark across asmall gap in the exploring antenna. Inversely,at hundreds of miles distance from thewireless sending station, the extremely weakwave is still observed in the receiving antennaby a change of the surface tension of aplatinum hair wire dipped into an electrolyte,the change in resistance of which operatesa relay. By exploring antenna, electricwaves have been studied and observed up tofrequencies of hundreds of millions of cyclesper second-so-called "Hertzian waves,"-as they. occur in industrial circuits betweenthe end cylinders of high voltage multi-gaplightning arresters. There, they are thecause of the high sensitivity of the arresterfor high frequency disturbances. *We have to realize though, that light andradiant heat, the Hertzian waves, the wavesof the wireless telegraphy station, the alter-nating fields of our transmission and distri-bution circuits, are one and the same phenom-enon--electric waves traveling through spaeewith the same velocity (188,000 miles persecond) and exhibiting the same character-istics, but differing merely by their fre-quencies. This docs not mean that electricityand light are the same, but that light is. anextremely high frequency electric wave, anextremely rapid alternating electric field,while the electric field of the direct currentis a steady stress in space.From our knowledge of the identity of thealternating electric field and the wave of lightradiation, we ean derive a number of interest-ing relations between electric phenomena andthe phenomena of light. To mention

Dr. Steinmetz here went on to point out that Cor frequencies of hundreds of thousands of millions, or millions of millionsof cycles per second, the above method of observing the electricwaves fails' however, they may be detected by placing a con.ducting body in their path. when they manifest themselves as"radiant heat." Frequencies of several hundred millions ofmillions are ap(,arent to the eye as light. wbile frequencies often thousand millions of millions probably constitute the Xvrays.For the full discussion of this subject, see Dr. Steinmetz's paperon " Arc Lighting" in the December, 1911, issue of the REVIEWpage !)6R-EDITOR

Digitized byGoogle


4/8

8 GENERAL ELECTRIC REVIEWonly one: the secondary current is re-pelled by the alternating magnetic fieldwhich induces it, that is, by the electric waveimpinging upon it. This fact is made use ofin the constant current transformer forconstant current regulation. Applying thesame phenomenon to the extremely highfrequency light waves, means that the bodywhich intercepts the light wave is repelled bythe wave-the radiation pressure. Thus atextremely high frequencies the radiationpressure is the analogous phenomenon tothe repulsion between primary and secondarycircuits in our industrial circuits.So far we have made no hypothesis, butmerely recorded the facts: we can measurethe waves and their frequencies, their velocityof propagation and other characteristics, andshow their identity. We may now speculateon the nature of the electric wave, on themechanism of its propagation, etc.; but mustthen realize, that as soon as we leave thefacts and indulge in speculation, we submitto uncertainty, which every hypothesis has,no matter how well founded.The velocity of propagation of the electricwave is incredible, but it is a finite velocity,and after the electric wave has left thesending antenna, a finite time elapses beforeit is observed by the receiving antenna. Theenergy sent out by the oscillator, the electriccircuit, the sending antenna, is thus receivedby the receiving antenna at a later time.The finite speed of propagation of the electricwave implies that the energy during itsmotion from the starting point to the pointobserved must reside for some time inintervening space. This means that theremust be something in the space whichcarries the energy; a carrier of the energy ofradiation, of light. That carrier we explainby. the hypothesis of the luminiferous ether.We assume that the ether permeates all space,is of extreme tenuitv and fineness, and is thecarrier of the electnc wave. The questionarises: Is the ether a mere hypothesis, oris it real? Is it a form of matter or not?\Ve may speculate on that, but may cometo one conclusion or to the opposite conclusion,depending on our definition of what matteris. After all, it is really not a question ofspeculation, but a question of definition-ofwhat vou define as matter.We' always speak of the phenomena ofnature within the conception of energy andof matter. Energy we can perceive by oursenses. All we know of nature, all 'that oursenses give us as information, is the effect of

energy-cnergy which reaches our bodythrough the eyes, through the ear, throughthe sense of touch; and if I were to make adefinition of energy it would be "that thingwhich reacts on, and is perceived by, or canbe perceived by, our senses." This isprobably the most consistent definition ofenergy.

Now, what is matter? We cannot sec orget any knowledge of matter. If we sec athing, we do not see the matter, but we seethe radiating energy from it which comesto us. We feel the mechanical energy of itsmomentum, but the matter we cannotperceive. All the conception of matter is asthe carrier of energy; but if you define matteras the carrier of energy, then the ether whichcarries radiating energy-carries the energyof the electric wave-is just as much matteras the bullet which carries the mechanicalenergy that was supplied to it in the gun.The question then arises: What arc theproperties of this ether, which is the carrierof the electric wave? The velocity of propa-gation of a wave in a medium depends on itsdensity and elasticity. The velocity ofpropagation of the electric wave through theether is nearly :200,O()()miles per second,while the velocity of sound waves throughthe air is about 1000 feet per second, or theelectric wave moves a million times fasterthan the sound wave. This means that theether must be of a density inconceivablylower than that of air, though we speak of theair as being of low density, and realize thiswhen trying to navigate it. Furthermore,through the ether all cosmic motion takesplace: our earth rushes through it at highvelocity, and still there is no appreciablefriction. That means that the densitv of theether must be so enormously low that evenat very high velocity the frictional resistanceis inappreciable.We might then consider the ether as a gasof inconceivably low density.However, the light wave or electric waveis a transverse vibration; that is, the oscillat-ing ether particles oscillate at right anglesto the direction in which the ray of lighttra vcls, and therefore in their oscillationcome neither nearer nor recede further fromthe ether particles in front or behind in thedirection of the beam of radiation. The oscilla-tion cannot be transferred from ether particleto ether particle in the direction of the beam,by approach or recession of the ether particles,and the transfer of oscillation in the directionof the beam thus can occur only by some

Digitized byGoogle


5/8

ELECTRICAL DISTURBANCESthing, some force, which holds the etherparticles together, so that a side motion of onecauses a corresponding side motion of theparticle ahead, without approach. That is,the ether particles can not be free as in a gas,but must be held together with some rigidity.In other words, the existence of transversevibrations precludes that the ether is a gas,and requires it to be a rigid body, a solid:transverse oscillations can occur onlv insolids, but are inconceivable in fluids. Fromthe nature of the wave motion of light, wethus would have to conclude that the ether,through which the earth and all bodies rushwith high velocity, and without appreciablefriction, is a solid. This is physically impos-sible, and here we find a very commonphysiological phenomenon: if we attempt tocarry any speculation or theory to its finaland ultimate conclusion, we reach contra-dictions. This probably is not the resultof the nature of the phenomena, but is inthe nature of our minds, which are finite andlimited, and therefore fail when attemptingto reason into the infinite.A speculative hypothesis on the nature ofelectrical phenomena has in the last yearsbeen developed in the ionic theory. Itsstarting point is the study of the phenomena.of conduction, more particularly the conduc-tion of gases and vapors. In this, we mustnot merely consider typical cases, but coverthe entire field of conductors. On first sight,it appears easy to divide all electric conduc-tors in two classes: metallic conductors orconductors of the first class, in which theresistance slightly increases with increase oftemperature, and electrolytic conductors orconductors of the second class, in which theresistance slightly decreases with the temper-ature. Further investigation shows, however,that there are numerous conductors whichdo not belong in either class, such as gases,vapors, etc., and that there are all transitionstages between the different conductorsrepresented, so that we can not speak ofclasses any more, but merely of types. Thusthere are solid conductors, such as metallicoxides (for instance magnetite) and elementsand their alloys, as silicon, etc., which, witha change of temperature, gradually changefrom metallic conductors of positive temper-ature coefficient to conductors of metalliccharacter, but with negative temperaturecoefficient; and which at still other temper-atures have such high negative temperaturecoefficients that the voltage decreases withincrease of current, thereby having the same

characteristics as arc conductors; while atstill higher temperatures they become electro-lytic conductors. Such" pyroelectrolytic"conductors, to which the Nernst lamp glowerbelongs, are interesting because of the changeof type of their conduction. Equally, if notmore interesting, are gases and vapors asconductors, such as the arc, the Geissler tube,the static spark, etc. There seem to existtwo classes of gas or vapor conduction:to the one belong the arcs, while to the otherbelong the Geissler tube and the electro-static spark. Again, on first sight, it appearsdifficult to realize that the silent faintlyluminous Geissler tube discharge, and thebrilliant and noisy electrostatic spark, are oneand the same phenomenon. However, theone changes gradually and without dividingline into the other by a change of gas pressure,and the differences, therefore, are duemerely to the difference in the gas pressure.Furthermore, the usual noise and brilliancyof the static spark at atmospheric pressure islargely the result of the circuit conditionunder which it is produced: the passage ofthe spark closes the circuit and therebystarts a momentary more or less unlimitedflow of electric energy. If however, thisshort circuiting effect of the spark is elimi-nated, as for instance by interposing betweenthe spark terminals a glass plate which isnot punctured, the electrostatic sparks appearas thin colored moderately luminous dis-charges which pass with moderate noise,the apparent difference from the Geisslerdischarge being then far less. With decreas-ing gas pressure, the electrostatic sparkbecomes less noisy, less brilliant, longer andthicker, and finally changes to the noiselesssteady stream of the Geissler discharge,which traverses the space between positiveand negative terminal with a glow, its colordepending on the nature of the gas: forexample, the glow is pink with air, orange-yellow with nitrogen, green with mercuryvapor, etc. Going still to higher and highervacua, the conductor which passes thecurrent between the positive and negativeterminal of the vacuum tube finally changesagain and becomes a green discharge, whichissues from the negative terminal in straightlines, like a beam of light, irrespective ofwhere the positive terminal is located. It maynot reach or come anywhere near the positiveterminal, and if the positive terminal is lo-cated back of the negative terminal, thecathode ray, issuing from the latter, willreally proceed away from the positive terminal.

Digitized byGoogle


6/8

10 GENERAL ELECTRIC REVIEWNow this form of electric conduction (and toa considerable extent the conduction of theGeissler tube at lower vacuum) looks verymuch like electric convection: it looks as ifthe electric energy were earned across the

terminals by luminous material particles,which are shot off, in straight lines, from thenegative terminal with great energy, produc-ing luminosity where they strike; and afterlosing their luminosity have to find theirway to the positive terminal. The transferof electric energy by the cathode ray wouldthen have the same relation to the transferof electric energy by a copper wire as thetransfer of kerosene bv a series of tank carshas to the transfer of kerosene by a pipe line.Assuming then the hypothesis that thecathode ray is the transfer of electric energyby convection by material particles, we willsee what conclusions we can derive there-from.A material particle containing electricenergy is acted upon by an electrostaticfield, in a direction depending on the polarityof the electric energy, whether positive ornegative against surrounding space. Thecathode ray, if consisting of material particles,thus would be deflected by an electrostaticfield by an amount depending on the intensityof the field and on the energy, mass andvelocity of the material particles. Thisis the case: the cathode ray is deflected,and measurements of the deflection of thisray by the electrostatic field thus give us arelation between electric energy, mass andvelocity of the cathode ray particles. Movingelectric energy, whether flowing through ametal conductor or earned by a movingparticle, is acted upon by a magnetic field.The cathode ray thus should be deflectedby a magnetic field by an amount dependingon the electric energy, mass and velocityof the moving cathode particles. This is thecase. From these two relations, given bythe deflection of the cathode ray by theelectrostatic and by the magnetic fieldrespectively, we can calculate the mass andthe velocity of the moving cathode rayparticles. If the masses of the cathode rayparticles, calculated by this assumption, werefound to be of the same magnitude as massesof other particles, calculated by other means,such as the chemical atoms or molecules,-if their velocities were comparable withother known velocities,--this would be astrong confirmation of the hypothesis ofelectric convection by the cathode ray,that is, of the ionic theory. However, this is

not the case, and the experiment thereforeneither confirms nor contradicts the ionictheory. The calculation shows that, if theconduction of the vacuum tube is by con-vection of electric energy by moving particles,these particles, called electrons, must bevery much smaller than the chemical atoms,or of a magnitude of one thousandth the sizeof the smallest chemical atom, the hydrogenatom. Their velocity of motion must beinconceivably high-comparable with, thoughsmaller than the velocity of light. Theycarry electric energy at a negative potentialagainst surrounding space, that is, theelectron may be considered as the negativeterminator of a line of dielectric force, whilethe positive end of this line of dielectricforce terminates at the positive terminal ofthe vacuum tube, or at a positive electron,where such exists.The question then arises: What is theelectron? By the derivation of its hypotheti-cal existence, it is a form of matter, since itsmass has been calculated by the action offorces on its mechanical momentum. It thuswould be a new form of matter, a new chemi-cal atom, a thousand times smaller than thehydrogen atom. It has been called "anatom of cleetricitv.' As "electricity" isa vague term without physical meaning,which has looselv been used for "electricquantity" (and even "electric quantity" isa mere mathematical fiction, a componentfactor of electrical energy) no objectionexists to giving the name "electricity" tothis new hypothetical form of matter, repre-sented by the electron. Itnaturally docs notexplain anything: The electron certainlyis not electric quantity, nor is it electricenergy, but it may be defined as that form ofmatter which is the carrier of electric energy.Then, however, the electron in its definitioncomes rather close to the hypothetical etheratom, which is the carrier of radiant energy,that is, the carrier of the energy of the electricwave in space.The electron, however, can not be con-sidered as electric energy, nor as representingor carrying a definite amount of electricenergy, even when associated with a definitequantity of electricity. no more than theiron atom of a magnetic circuit can beconsidered as magnetic energy, or as carrierof a definite amount of magnetic energy.Energy comprises the product of quantityand intensity, and the electric energy carriedby the electron is its electric quantity timesthe intensity of its electric field, that is,

Digitized byGoogle


7/8

ELECTRICAL DISTURBANCESthe potential gradient along the line ofdielectric force, which starts at the electron,up to a referencepoint on this lineofdielectricforce-the potential of the positive terminal,of surrounding space, of the universe, oranything else. This disposesof the mistakenconception, occasionally expressed, that theelectron represents a definite amount ofelectric energy, and leaves the amount ofenergy of the electron indefinite, that is,depending on an arbitrarily chosen referencepotential, just as it is with any other form ofenergy: the amount of energy of any carrierof energy, such as a moving body, is alwaysrelative, depending on a reference point.Obviouslythen, electric energy.can not bemeasured by the number of electrons, andhas no direct relation to it, but depends on theelectric intensity, or potential difference.

In the last years, the ionic theory has beengreatly strengthened by the discovery andinvestigation of phenomena similar to thoseof the cathode ray, though more general innature, in the radiation of so-called "radio-active substances." A number of chemicalelements, such as radium, thorium, uranium,etc., continuously send out rays of variouskinds. Someof these, the {3 rays, are identicalwith the cathode rays of the vacuum tube,or, in other words, are deflected in the samemanner by electrostatic and magnetic fields,and are therefore considered as electrons-terminators of the negative end of a line ofdielectric force,of a mass about a thousandththat of the hydrogen atom, shot off by theradio-active substance with velocities ap-proachingthat oflight. Other rays, the arays,are deflected in an opposite direction byelectrostatic and magnetic fields, and thusmust be considered as carriers of electricenergy of positive potential: positive elec-trons. Their mass, as calculated in themanner above described, is that of thehelium atom (4 times the mass of the hydro-gen atom), and they are therefore generallyconsidered as helium atoms carrying electricenergy of positive potential. They areshot offwith velocitiesvery much lower thanthe velocitiesof the negative electron, thoughstill inconceivably high. When carryingelectric energy, they contain the samequantity of electricity at positive potentialthat the negative electrons carry at negativepotential, and if the, latter are considered asterminators of the negative end of a line ofdielectric force, the helium atoms as positiveelectrons are terminators of the positive endof a line of dielectric force.

11A third class of rays, issuing from radio-active substances, are the 'Y rays. They havethe same characteristics as the other rays,except that they are not deflectedby electro-static or magnetic fields. They are identical

in their properties with the X-rays, discussedabove as electric waves at the extreme endof high frequencies, and are usually con-sidered as X-rays.Here we come to one of those conclusionswhich do not appear rational: the a, {3 and 'Yrays are very similar in their nature, differingonly by the direction and amount of theirdeflection, and it therefore does not appearreasonable to assume that the 'Y rays are etherwaves, while the a and {3 rays are projectilesthrown off by the radio-active mass. Theattempt ofavoidingthis dilemmaby assumingthe 'Y rays to be projectiles,which carry equalpositive and negative electric quantity, andtherefore are not deflected, appears forcedand merely transfers the difficulty into therelation between X-rays and ultra-violetlight. The latter is generally conceded-andcorroborated by the phenomena of inter-ference, etc.-to be ether waves. At theextreme ultra-violet, however, the propertiesbegin to shade into those of the X-rays, andit again appears unreasonable to assume suchan essential difference between ultra-violetand X-rays, as that the one are ether waves,the other projectiles.In many instances, when we follow thereasoningof the ionic theory to its conclusion,we meet contradictions. For instance, thecalculation of the mass of the electron showsthat at very high velocities the mass is notconstant, but increaseswith increasing veloc-ity, becoming infinity; and therefore thekinetic energy of the electron becomesinfinite, if its velocity equals the velocity oflight. This is impossible,as it contradicts thelawof conservation ofenergy: if we considertwo electrons, moving in opposite directionsat half the velocity of light, their kineticenergy against surrounding space would befinite. Their relative motion against eachother, however, is at the velocity of light,and their kinetic energy against each otherwouldbe infinite. Since, however, they wereset in motion by finite energy, their relativeenergy can not be infinite. To overcomethis difficulty, a fictitious or apparent mass-the" electromagneticmass"-has beenattribu-ted to the electrons, which is not the mass ofmechanics. However, the calculation ofmass and velocity of the electrons isbasedonthekinetic energyofthe elec~ron,that is,onits

Digitized byGoogle


8/8

12 GENERAL ELECTRIC REVIEWmechanical mass, and not a newkindofmass,which is not a mass in the mechanical sense.These and other numerous contradictionsto which the conception of the ionic theoryleads, obviously do not mean that the ionictheory is fundamentally wrong in principle:we have also seen that the wave theory ofradiation, in the properties ofthe luminiferousether, lead to attributes that are contradictoryand thereby impossible. We find the samething in all theories-the chemical, the

thermodynamic, etc. Itsimply means thatour present formulation of the ionic theory,of the electromagnetic wave theory, and ofall other theories are very far from finalcorrectness, but are at best only very crudeconceptions of the nature of things, whichwill have to be modified again and againwith our increasing knowledge before we canexpect to reach a moderately rational con-ception of nature's laws and phenomena,if we ever arrive there.

THE GROUND CONNECTION IN LIGHTNING PROTECTIVE SYSTEMSPART I

By E. E. F. CREIGHTONCONSULTING ENGINEERING DEPARTMENT, SCHENECTADY

TerminologyThere is some confusion in the use of theword" grounded." Itis not unusual to hearsome one speak of a conductor as groundedto a cable sheath when the sheath itself isfairly well insulated from the earth. Againone hears of a phase being grounded to theiron case of a transformer when the case isinsulated from the ground by, say, a 30-footlength of dry wooden pole. This length ofdry pole would give an insulation of not lessthan a megohm.Another important case, and not unusualuse of the word "grounded" , occurs inrelation to lightning arresters. There aremany cases where "grounded" must meana connection to a conductor which is con-nected to earth in the near vicinity of thearrester. An arrester grounded to a waterpipe, however, may not have an electricalcontact to the earth within a hundred feetfrom the arrester. This is usually an ineffi-cient condition of protection. Although themeasured ground resistance may be accep-tably low, the inductance of such a long pathto ground is, usually, objectionable. The

important thing to knowmay be the distanceto the actual connection to terra firma.Again, an entirely contrary case may becited where the point of grounding of anarrester on a semi-insulated conductor is farmore important than its connection to earth.This condition exists in the protection ofapparatus on electrical railways. It is farmore important to ground a line arresterto a rail than it is to connect it to earth.(Using the same language, we have the

apparently inconsistent expression" to groundthe lightning arrester to earth. ")The general use of the word "ground" is anatural growth, since the lower terminal ofan arrester is called the ground terminalirrespective of whether it is to be connectedto the earth or not. The loose usage of"grounded" is too well established to alloweven a hope of making it definite. The wordis convenient but its indefiniteness is to bedeplored. Its indefiniteness becomes noinsignificant matter when some one, at adistance of several thousand miles, wantsadvice regarding a failure of protectiveapparatus, and the deciding feature is thevalue of resistance in the so-called groundto terra firma. This feature of resistance toearth is nearly always important, and theengineers who are called on in such casesmust choose between giving "snap" judg-ment, or causing a long delay in the mails inascertaining what wasmeant by "grounded. "In 1907, it was proposed to accept theterm" groundedto" asa particular equivalentto "connected to", and retain the older term"earthed" as meaning the actual connectionsto terra firma. After four years no improve-ment on this suggestion has been noted.To make the language definite and mutuallycomprehensible we would have such state-ments as the following: The arrester wasgrounded on the rail but the rail was notearthed; or, Aline wire was grounded on theiron caseof a transformer, ormetal cross-arm,but these iron parts were not earthed-orwere earthed through the high resistance of awooden pole; and so on. Whether the

Digitized by

Charles Steinmetz Electrical Disturbances the Nature of Electrical Energy 1912

Documents

Transcript of Charles Steinmetz Electrical Disturbances the Nature of Electrical Energy 1912