Lauffen-Frankfort Line and Oil Insulators

POWER AT DISTANCES.

Successful Transmission of Electric Currents.

EXPERIMENTS IN GERMANY.

Can the Great Force of Niagara Be Used?

The Fair Will Reveal the Developments in This Magical Science.

AN INTERESTING HISTORY.

The recent electrical exhibition at Frankfort-on-the-main was successful in more ways than one; but, in the opinion of the scientific world, it derives it's chief claim to remembrance from the experiments there conducted in the long-distance transmission of power electrically. As a matter of fact, every telegraphic or telephonic circuit of any length illustrates the same principal, for in each case is seen the performance of work by means of an electric current, hundreds of miles from the source of energy; but here analogy ceases, the aim in one case being the transmission of intelligence by a current as small as possible, whereas in the other case the object is to transmit in as large quantities as possible power that would otherwise go to waste or be poorly utilized on the spot. The fact that in teledynamics, as in telegraphy, electricity is destined, for the leading role impresses us with a further idea of its universality and flexibility.

The history of electrical-power transmission, says the New York Evening Post, is very brief but not a little interesting. A bare recapitulation will suffice to show the immense importance of the Frankfort-Lauffen work a point of new departure. At the Vienna exposition in 1873, the Gramme dynamo-electric machine, still a great novelty, was employed to drive another such machine as a motor, which worked a pump, the current being conveyed through about a mile of cable. This is the first piece of such work on record, and it stood practically alone, until some trials in ploughing by electricity were made in 1879 by Felix and Chretien at Sermaize, in France. In 1879 Seimens and Halske followed up the idea in operating an electric road at the Berlin Exposition, and then a variety of demonstrations were made at the celebrated electrical exposition in Paris in 1881. Still, all these experiments had been limited to short distances. The first real "long distance" work came to notice in 1882 at the Munich Exposition of that year. There Herr Schuckert ran a three horse-power motor with current from a generator placed at a waterfall about six and one-quarter miles away. This was insignificant, however, alongside the feat of M. Marcel Deprez, who, with two Gramme machines, one as a generator and the other as a driven motor, transmitted a little over one horse-power from Miesbach to Munich, a distance of thirty seven miles, using an ordinary iron telegraph wire for the circuit. The motor was placed in the Munich Crystal Palace, and there ran a centrifugal pump feeding a pretty cascade. The absolute efficiency of transmission appears to have been about 28 per cent.

Encouraged by these results and securing the aid of the Rothchildes, M. Deprez launched out on bolder work and attempted the transmission of 50 horse-power from Creil to Paris, a distance of thirty four miles. But it was found that the conditions were against success. According to the reports made by M. Deprez to the French Academy of Sciences, 40 horse-power was transmitted with an efficiency of about 50 per cent, the current having the high electro-motive force of 5,717 volts in the generator and 4,441 in the receiving motor, the intensity being 7.20 amperes. But the machines were unable to stand so high an electro-motive force, in spite of their special and careful insulation, and broke down by the time M. Duprez had reached 6,000 volts. It was as though the attempt were made to carry steam of 500 or 1,000 pounds of pressure to the square inch without having engines or boilers equal to the strain.

Here experiments with "continuous" currents rested, for not only were the armatures found wanting, but the commutators also gave trouble. A great stimulus was given, however, to power transmission at lower voltage over shorter distance, so that to-day we have in the United States alone over 400 electric roads, some ten miles long; and probably 50,000 stationary electric motors doing industrial work, some of the twenty-five horse-power, situated more than a mile from the central station that supplies them with current. The enormous success of this work soon led to a revival of the interest in long-distance schemes, and the exploitation of operative alternating current motors by Nikola Tesla in 1888, opened a way for the realization of many hopes. One of the leading features of such motors is that they dispense with the troublesome commutators and another is that with alternating currents, much higher voltages, or rates of delivery, are feasible then with continuous current. Thus it came about that in making plans for the Frankfort Electrical Exposition of the present year the suggestion was put forth to try an electrical power transmission of a kind and on a scale never before attempted. It is needless to say that, with the historic precedent of Munich in 1882 before the managers.

The happy thought was at once taken up, and the bold plan was propounded of utilizing the water power at Lauffen, a romantic little village on the rushing Neckar, nearly 120 miles away from Frankfort. It was an expensive experiment to make, but, as Germans were to carry it out this time and not a Frenchman, all the Fatherland took a patriotic interest in it. The German Emperor, so strikingly alive to anything that might promote the glory of the country, contributed 1,000 marks. The Exposition Company did the same. Three hundred and sixty miles of copper wire -the circuit being "metallic" and not using the earth as a return -was lent free of charge by P. A. Hesse & Sons, of Heddernheim. The apparatus and the actual work was done by the Aligemeins Electricitats Geselischaft, of Berlin, and the Oerlikon Works of Zurich, these firms having the expert assistance of two well-known electrical engineers, Mr. C. E. L. Brown and Professor M. von Doliva-Dobrowolsky.

The proposition of the designers of the plant was to transmit the current at an electromotive force of 30,000 volts if possible or if necessary, but it does not appear that at any time a higher rate than 18,000 volts was reached. The dynamo generating the current and installed at Lauffen, where it was driven by turbine, was a three-phase alternator, and each component of its current had a pressure of fifty volts with a delivery of 1,400 amperes. From this machine the current was led to a switchboard, whence it went to a "transformer," an induction coil, which converted the current of heavy amperage into one of very small amperage and very high voltage, namely, 13,000 to 18,000 volts. Owing to the tendency of the current to jump from the conductor it traversed under such high tension, the transformer or "converter" was placed in oil which affords, it is believed, the only insulation adequate to the purpose, it being found impossible to spark through it. This transformer of converter is known as the "step-up," because it raises the voltage, although in this country it enjoys the more racy and expressive name of a "booster." At the Frankfort end of the line the current was received by three "step-down" converters, so called because they lowered the voltage. These receiving the current at say 15,000 volts, reduced it to 100 volts. Of course, as will be readily understood, by properly partitioning the "primary" and "secondary" wires in these double-wire induction coils, or transformers, the current can [be] manipulated within wide ranges. The great feature of advantage is that it can thus be made to travel over the line at great velocity, and the higher the potential , or "head," the smaller the wire necessary for its transmission, as in the analogous case of water. In this case the circuit from Lauffen to Frankfort consisted of bare copper wire four millimeters in diameter. Tt was carried chiefly along the railroad on poles eight meters high and sixty meters apart, or 3,000 for the whole distance. The wire was fastened to oil insulators, the principle of which is that they have one or more lips turned up inwardly, so as to contain the liquid, which prevents by its presence the leakage of the current to earth, especially when tempted to do so by moisture or dirt, both of which are apt to accumulate on the ordinary glass insulators that everybody is familiar with. It was the intention t equip the line throughout with insulators having three lips for oil, but they were not ready in time, and hence for about two-thirds the distance insulators having but one oil lip or receptacle were employed. This is said to be one of the reasons why the upper limit of voltage proposed was not reached, although the real reason is reported to be the heating up of other oil in the tanks or jackets in which the transformers themselves were placed. Anyhow, even with the lower potential of 15,000 volts, the line was considered something best admired at a distance, and therefore every pole was festively adorned in staring paint with a death's head and cross-bones. The object was to warn away any bucolic Bavarians, or other people who might venture near the line, and who might not be aware that, while all precautions had been taken, the current was apt to get astray and to manifest pernicious activity.

So far no actual tests have been published as to the efficiency of the transmission. The dynamo at Lauffen was equal to generating a current of 300 horse-power, but perhaps never more than half this was sent over the line to the exhibition, part of it supplying current for incandescent lamps there and part of it being used to drive "rotary phase" motors, one of which kept a thirty-foot waterfall going, and thus illustrated a complete cycle in the transmission of energy, beginning with the waterfall at Lauffen. The authorities intrusted with the experiment was 40 per cent, namely 20 percent in the dynamos and transformers, and 20 in the line, leaving 60 per cent available for conversion into light and power. It does not appear that the work was maintained steadily for any length of time, a fact due possibly to the heating up unduly of the oil jackets spoken of before. Be this as it may, the experiment was bold and has proved, so far as it has gone, very successful. It certainly drew to Frankfort a great crowd of savants, and has aroused the curiosity of mechanical and electrical engineers in every quarter of the globe.

We are now told that the same idea is to be followed at a transmission of power from Niagara to the World's fair at Chicago, but what people want to know is, whether these methods will answer, not merely for sensational displays, but in average plain industrial operations. One of the leading English electrical papers says that it is "inclined to look upon the whirling of the three-phase armature at Frankfort, in more senses than one, as a tour de force." Mr. Edison has expressed the opinion that he can do as much with continuous currents as these experiments show to have been done with alternating. One of the commercial plans is to transmit the power of Niagara to Buffalo, but it may prove cheaper to utilize Niagara on the spot than to carry the energy of the great fall up stream again to a city reveling in natural gas and boasting of its position as the center of coal supply for a large part of Canada and the Eastern States.

But no such demonstration as this is wasted, and there is good cause for believing that in many parts of the country, by means of alternating currents, power will thus be transmitted from rivers and waterfalls and used profitably, even if the efficiency should rise above 60 per cent. It is, meantime, a source of satisfaction to know that the principals and methods used in the Frankfort-Lauffen experiment are American if they are anything. Nikola Tesla, a Likan from the Turkish borderland of Austria-Hungary, and now an American citizen, was the first man to develop the multi-phase and rotary-phase alternating system, and did his work on it here. The use of oil and parafine as insulators was first made by the late David Brooks, of Philadelphia, a pioneer of the telegraph field; and the first specific patent on oil-cup insulators was taken out in 1869 by Mr. W. E. Simonds, of Hartford, now United States Commissioner of Patents. The English reinventors did not secure a patent until seven years later. As to the idea of marking off such circuits as dangerous, that was proposed by Mr. F. L. Pope, then President of the society, before the American Institute of Electrical Engineers in this city in 1886, when he said" "Let us suspend these high potential lines on poles on a strip of land -a right of way which we will buy and own as a railway company does -and if anybody goes on there and trespasses or meddles he is a dead man; he takes the risk." And when New York is supplied electrically by power drawn from the rushing streams of Connecticut, the mammoth culm piles of Scranton, or the natural gas and oil wells of other parts of Pennsylvania, there is no doubt that in just such wise the circuits will cross the country intervening.