1942: Electrical Engineering

Equipment.

Electrical Engineering and the War Emergency.

The electrical engineering industry, particularly the power and the telephone and telegraph companies, together with the manufacturers, have adopted many unusual measures to enable them to meet the conditions imposed by the war emergency. The utilities have been obliged to meet increased demands without being able to procure new equipment that is at all commensurate with the added load on their systems. The general plan is to subordinate the economy of dollars to the economy of materials.

The increased loads have been met in many ways. Fortunately, in the past much of the equipment was designed with a liberal margin of safety and this spare capacity is now available. The War Production Board has ruled that new designs should contemplate only immediate demands and the design of the apparatus should be based on a possible life of not more than five years. Hence, at the expense of shorter life, the output of machines and apparatus, for a given amount of material, has been increased considerably over that obtained during normal conditions.

In addition, the power companies have increased the use of their existing facilities by operating cables, generators and transformers at higher temperatures. This procedure has increased power capacity in the country by 2,000,000 kw. This of course shortens the life of such apparatus. Tests have shown, however, that the output of transformers for peak loads of moderate duration may be increased 40 to 50 per cent, and for short peaks, 100 per cent, without undue injury. The output of transformers is also greatly increased by spraying the cases with water, thus increasing the cooling effect. Another method is to utilize less efficient apparatus that has been kept for standby purposes. Unused cables in the ground are being put into lower-voltage service, abandoned cable is being withdrawn and salvaged. Also by rearranging circuits economies have been effected. Transmission and distribution circuits have been combined, a single neutral being made common to several circuits. For example, in distribution circuits, a common neutral is used for both primary and secondary. Also short lengths of cables are being spliced to form long lengths. Underloaded transformers are being removed to locations where they are more effectively used while smaller ones take their places.

The utilities have arranged to exchange equipment and inventory. Frequently one utility will have a piece of apparatus that it does not need, but which could be used advantageously by another. This 'swapping' has been conducted to a high degree with watt-hour meters. Many substitutions are being made. The only new services being installed are essential ones. A saving of 40 per cent in house wiring is effected by the use of the bare grounded neutral wire system. Solderless connectors release solder and hence tin. In soldering operations, the men are being given special training which has resulted in a saving of 38 per cent in solder. Better materials and design save materials.

In the telephone field, economies are effected by discontinuing the replacement of dialing equipment with improved types; increasing the use of carrier systems whereby twelve to sixteen messages are carried over a single pair of wires; replacing open overhead wires by small-gage cable pairs; improving the operating methods; moving the more skilled operators to positions where the traffic is greatest; and urging customers not to use times of peak load.

Westinghouse Super-Power Testing Laboratory.

When short circuits occur on power systems, it is the duty of the circuit breaker to interrupt the tremendous short-circuit currents, just as an ordinary fuse opens the circuit when a short circuit occurs in the usual house lighting circuit. However, in the case of the power system the amount of energy to be interrupted is so great that great skill is required to design a circuit breaker that can interrupt the current without itself being destroyed by the hot arcs created by the act of opening. Moreover, it is important that the circuit be interrupted in a minimum interval of time, before damage to the connected apparatus can occur. Furthermore, it is desirable to be able to test the circuit breakers at the factory before being placed in actual duty. The difficulty comes from attempting to reproduce in the factory the actual tremendous amounts of power that exist in the actual power system. The Westinghouse Company has just completed a Super-Power Testing Laboratory where 2,000,000 kw., twice the power generated at any instant at Niagara, can be interrupted without harm.

In demonstrations before Army and Navy officers short-circuits, such as might occur if a saboteur threw a bar of steel across power station bus-bars, were produced. The power suddenly released produced arcs 20 feet in length and exploded old time fuses with a noise like exploding shell fire, and 6-inch timbers were shattered into kindling wood. However, the new improved 12-foot-high circuit breakers snuffed out the arc in one-twentieth of a second. This is accomplished by by-passing the arc into a chamber where it is choked off by the blowout action of a magnetic field.

Industrial Plants Adopt Secondary Network.

The secondary network, which for some time has been used in the thickly settled parts of cities and in downtown districts, consists usually of a 3-phase, 4-wire, 208/120 volt low-voltage network or loop fed at two or more points by network transformers the primaries of which are connected to a feeder directly from the substation, usually at 6,900 or 13,800 volts. Relays operating to disconnect almost instantly any faulty transformer and its feeder, and the fact that two or more independent sources of feed are available, give a high degree of reliability to the system.

Electric Power and Synthetic Rubber Plants.

By making steam do two jobs instead of one in the new synthetic rubber plants, not only will electric power sufficient to run the plant be generated, but there will be considerable to spare to the utilities to help supply war industries. A large amount of steam is required in the chemical processes in making butadiene and styrene for Buna S rubber. The steam at high pressure can first be passed through the steam turbines, where mechanical work is extracted from it, and then into the chemical vats where the chemical changes take place. The turbine can extract only a relatively small proportion of the heat units available in the steam, so that ample heat remains for the chemical processes. Hence the electric power is for the most part a 'by-product.' The Westinghouse Company is now building three turbine-alternator sets, one of 35,000 kw. and two of 40,000 kw. each for this type of service.

Silver Replaces Copper.

The War Production Board has announced that within a few months 24,000,000 lbs. or 12,000 tons of copper had been saved by substituting silver for copper for electrical conductors. This saving represents sufficient copper to make 95,000,000 aircraft machine gun bullets in addition to 600,000 anti-tank shells and 1,500,000 anti-aircraft shells. Copper is being replaced by silver in plants where electrical connections are a significant feature of the apparatus or installation, such as bus-bars, transformer windings, and similar conductors.

Lightning.

Artificial Lightning Generator.

In order to test electrical power apparatus such as generators, transformers, circuit breakers and lightning arresters as to their ability to stand up under lightning conditions, electrical manufacturers have constructed impulse or artificial lightning generators which deliver strokes which simulate natural lightning. The General Electric Company has recently installed in its Pittsfield testing laboratory an impulse generator rated at 3,000,000 volts with the added ability to store a large amount of electrical energy. It is constructed in the form of Herkolite columns consisting of stacks of units and is similar to the lightning generator displayed at the New York World's Fair. There are four vertical stacks consisting of series-connected capacitors of 100,000 volts each. Such generators operate as follows: during charging certain groups of the series-connected capacitors are connected in parallel through high resistances of approximately 20,000 ohms for each 100,000 volts. The series connection of the capacitors on discharge is effected through sphere gaps, which, until the generator discharges, are open circuits. The capacitors are slowly charged in parallel through a kenotron which is a high-voltage rectifying tube, supplied with alternating current by a step-up transformer. When the charge in the capacitors reaches the predetermined value, one sphere gap is discharged usually by a relatively low outside trigger voltage being applied to it by the operator. This trigger voltage discharge precipitates the discharge of all the series sphere gaps, so that the entire stack of capacitors is now connected in series through the comparatively low resistances of the arc discharges in the sphere gaps. The voltages of the parallel sections are now connected in series so that the total generator voltage is that of the parallel sections multiplied by the number of sections connected in series by the sphere gaps.

Effect of Lightning on Thin Metal Surfaces.

That lightning may write its own history by the number, type and size of hole which it produces in thin metal surfaces was shown in a paper presented by K. B. McEachron and J. H. Hagenguth of the General Electric Company of Pittsfield, Mass., at the Convention of the American Institute of Electrical Engineers held at Chicago last June. For six years a nickel-plated 18-in. copper sphere located 878 ft. above the ground atop the WSM radiator at Nashville, Tenn., had been collecting data on lightning. A total of 150 holes and 300 pits were found in the metal. In a lightning storm in 1937 the ball was thrown to the ground. Of the 150 holes, 89 were found in the upper half and 61 in the lower half with a great majority appearing within a 6-in. belt around the seam of the ball's equator.

In order to determine the value of the lightning strokes as represented by the size of holes, experiments were made in the laboratory on thin sheets of copper using an impulse or artificial-lightning generator. However, it had been found that the artificial-lightning generators of themselves did not produce the fusing effects that are produced by natural lightning. Investigation showed that this was due to the lack of a 'follow up' current, present in natural lightning and not in that produced by the impulse generator. To supply this current in the laboratory a 600-volt d-c generator is connected between the carbon electrode that conducts the lightning current to the copper sheet and the ground connection. The high-voltage impulse initiates an arc between the electrode and sheet and the current supplied by the d-c generator then follows, producing the fusing effects.

By comparing holes obtained with artificial lightning in the laboratory with those existing in the sphere, it was found that the average hole corresponded to 15 coulombs (amperes times seconds) whereas the maximum hole corresponded to 240 coulombs. Thus, by determining the size of holes produced in sheets of metal it becomes possible to determine the charge contained in a lightning stroke.

Ultra-High-Speed Oscillograph.

In order to study high-frequency alternating currents such as occur in radio circuits, and also extremely fast transients such as lightning strokes, a cathode-ray oscillograph is used. This consists of an evacuated tube, a source of electrons such as a hot filament, an accelerating voltage, deflecting plates and either a fluorescent screen or a film, depending on whether visual study or a photographic record is desired. There are other accessories such as a sweep circuit and timing plates which cause a linear motion with time of the beam across the screen, a focussing coil and trap plates which remove the slow moving ions which might fog the film. By means of the accelerating voltage, a small circular aperture, and the focussing coil, the beam is focussed to a small point on the screen. The electromotive face of the phenomenon to be studied is applied to the deflection plates, and these together with the timing plates cause the beam to 'write' the wave either on the screen or film.

Materials.

Glass Jewels.

In electrical indicating instruments and watt-hour meters the moving element is mounted on a spindle which terminates in sharp pivots. (With watt-hour meters there is only a bottom pivot.) These pivots operate in cup-shaped or V-shaped jewels, thus minimizing friction. Heretofore, sapphire jewels have been used almost exclusively, but the supply has been nearly cut off by the war, and at a time when a tremendous quantity of miniature instruments is required, particularly for airplane panels. To meet the demand General Electric engineers have developed jewels of glass, called Vee jewels. It is found that, so far as miniature instruments are concerned, there is little to choose between the new jewel and sapphire.

Latex-Insulated Wire.

Latex-insulated telephone wire is produced by a multiple-dip process using a special latex compound. The wire so insulated weighs only 30 lb. per mile as compared with 168 lb. per mile of the older-type wire. The Government has already ordered more than 100,000 miles of the new wire, enough to go around the earth four times. It has become possible to make a new synthetic latex from reclaimed rubber. Other articles besides wire insulation, such as gas masks, bullet-proof gas tanks for airplanes, and aviators' helmets are made from special latex.

Cellulose Acetate Yarn for Wire Insulation.

For years silk has been one of the most desirable materials for insulating electric wires. It has been particularly satisfactory for telephone central-office wires because of its stable electrical characteristics under varying atmospheric conditions and because of its good aging characteristics. The insulation consisted usually of two layers of silk covered with a layer of cotton. Generally the insulation was covered with a cellulose-acetate lacquer coating. Ever since the introduction of synthetic fibers such as rayon into the textile industry consideration has been given to the possible use of these materials for insulating wire. The advantages would be a possible saving and an assured source of supply.

In early experiments with acetate yarn, the mechanical difficulties experienced in handling the wire more than offset the price differential between the acetate yarn and the silk. But new methods of handling and improvement of manufacturing processes have produced electrical characteristics superior to those of silk, and the material has proved to be entirely satisfactory so far as aging is concerned. Hence, acetate yarn has now replaced silk for this type of electric-wire insulation.

Molybdenum Permalloy Cores.

Loading coils consist of copper wire wound on a ring-shaped magnetic core, the finished coil having the shape of a doughnut. These coils are connected in telephone and telegraph lines every few miles, the object being to neutralize, in part at least, the capacitive effect of the wires themselves, thus increasing the distance to which the wire currents can be transmitted. For high super-audio frequencies, a core of permalloy powder has been used, the powdered form being used to reduce the eddy-current loss which otherwise would be prohibitive at these high frequencies. Permalloy is an alloy 81 per cent nickel and 19 per cent iron. The core is made by mixing permalloy powder with a plastic binder and moulding the core under tremendous pressure. Recently it has been found that the addition of 2 per cent of molybdenum increases the permeability (ability to conduct magnetism) 70 per cent and at the same time the losses, hystereses and eddy-current, are markedly reduced. For the same service this permits not only a reduction in the size of core, but the reduced size of core results in a saving of the copper wire as well, since the lengths of the turns are reduced also.

Applications.

Electric Marking Counter for Small Objects.

It is frequently desired to count the projected cross-sections of very small objects after they have been greatly magnified, such, for example, as 500 times. Although elaborate counting procedures have been developed for certain microscopic objects, such as bacteria, these procedures are not adapted to such applications as fiber counts in wool fibers. The new device consists of a laminated U-shaped iron core which is excited by a coil connected across a 110-volt a-c source, a delicate switch with silver contacts being in series. A laminated iron armature is so mounted between the poles of the core that when the core is energized, the armature is given a rotary motion through 45 degrees of arc. When the core is de-energized the armature is restored to its initial position by a spring. The rotary motion of the armature operates a counter. The switch is held on the pencil by a metal clamp. A slight motion of the pencil causes the silver contacts to close, which in turn causes the armature to actuate the counter. Hence, by means of the small movement of the pencil resulting from the marking of each fiber as it is counted, the total number of fibers may be counted accurately and without the fatigue usually resulting from direct counting.

Flaws in Steel Detected Magnetically.

Flaws in heat-treated parts such as bell- and roller-bearing races are detected quickly by a simple new magnetic method devised by P. H. Brace and C. S. Williams of the Westinghouse Research Laboratories. In addition to being fast and accurate, this electromagnetic test for flaws requires no contact with the inspected parts and performs its task without marring or dinting polished surfaces.

After a symmetrical piece of steel has been heat treated and then magnetized, the external magnetic field is uniform. However, any defect such as a hard or soft spot introduces an irregularity which is recorded by an oscilloscope or cathode-ray oscillograph. In making the test the piece is first demagnetized to wipe out all traces of residual magnetism and is then rotated at high speed and at the same time is strongly magnetized. The field is explored by an electromagnet consisting of an alloy bar surrounded by a coil. Variations of the magnetic field, due to irregularities in the piece, induce an electromotive force in the coil which is amplified and is shown visually by the trace of the cathode ray on the screen of the oscilloscope. The test piece is rotated synchronously with the cathode-ray sweep so that a uniform field (no flaws) is traced on the screen as a straight line, but flaws appear as dips in the line.

In addition to the visual indication, a relay system may be added to give an audible signal or to operate automatic machinery to segregate defective pieces coming from a production line.

High Frequency to Dry Plywood.

A unique development in electrical engineering applications is the use of high-frequency alternating current to dry the glue in the process of making plywood. The principle is that of an electric condenser, with a high-voltage, high-frequency alternating electromotive force applied across its electrodes, and a high-loss dielectric consisting of the plywood and glue which necessarily absorbs a considerable amount of electrical energy. The heat produced by this energy sets the glue in a comparatively short time, and accordingly speeds up production resulting in increased economy of manufacture.

In the process, the panels, with the wet glue between the plies, are stacked in the press to a depth of 9 inches and a metal-plated caul board is then inserted. Above this is another 9-inch stack. The caul is one electrode of the condenser and the top and bottom members of the press are the others. The wet plywood is of course the dielectric.

Power is obtained from the 4,400-volt, alternating-current distribution service and is stepped up by transformers to 15,000 volts and is then converted to direct current by means of a mercury-arc rectifier. This is converted to 2,000,000 cycles by means of mercury-vapor amplifier tubes. There are two presses and the total power consumed by them is 600 kw.

Illumination.

General Illumination Developments.

The number of incandescent lamps sold during the past year increased over 235,000,000 lamps, for the second time making the total exceed 1,000,000,000. More significant, however, is the fact that the demand for 200- to 1,500-watt lamps increased 16 per cent while that for lower-wattage lamps (7½ to 150 watts) increased only 6 per cent. Fluorescent lamps — not yet four years old commercially — showed a 300 per cent increase, and reached a total of 22,000,000. Many of the new light sources developed were the result of the war effort. High-wattage units of all-glass sealed-beam construction are guiding planes into safe night landings. Sturdy spotlights and flashing signal lamps are being used for communication on land, on sea and in the air. All-glass sealed-beam headlamps were produced for transports, trucks and buses having 12- to 16-volt systems.

The efficiencies, lumens per watt, of several lamps between 10 and 300 watts were increased; 300- and 500-watt medium bipost lamps with bulbs up to 2½ in. were made an inch shorter, so that equipments in which they were used could be made more compact.

A special 250-watt reflector lamp was developed for therapeutic purposes, and a 100 watt-lamp was added to the line of drying lamps. The two-filament three-light principle was applied to a 50-100-150-watt photo-enlarger lamp, and a 75-watt photo-enlarger lamp was made available for 28-32-volt electric systems. The life of the 100-watt fluorescent lamp was increased to 2,500 hours. An 8-watt lamp a foot long and a 65-watt lamp only three feet long were introduced. All sizes of fluorescent Mazda F lamps were made available in the 3,500-degree white and daylight type (almost all in soft white) and the six sizes from 14 to 40 watts inclusive were made available in the full range of red, pink, golden green and blue colors.

Photoflash Lamps.

A bit of special material on the lead wires, instead of foil, leaf or wire gives the light in a new Speed Midget photoflash lamp, with a bulb the size of a walnut. Its flash reaches the peak output in 3/1,000 second and is completed in less than 15/100 second, that is, while most lamps are climbing towards their peaks. It is for an open-flash 'bulb or time' photoflash.

The even long-duration flash necessary for focal-plane shutter cameras was attained in another small-bulb photoflash lamp. A third new photographic unit was designed primarily for newspaper men needing a high-peak-output lamp to 'get the picture' every time.

Fluorescent Lamp.

A new portable fluorescent lamp encased in a tube of transparent Lucite methyl methacrylate resin is now manufactured by Del-Ray Products of South Pasadena, Cal. The lamp is light in weight, of low wattage and tough, and is thus convenient for workmen by providing proper light in confined and inaccessible areas. It is very valuable where rushed assembly lines have moved outdoors. The lamp burns cool and emits daylight-like illumination, and gives off spherial lighting, thus eliminating shadows in limited working areas.

Fluorescent Light as Protection against Japanese Beetles.

W. A. Ramsay, General Electric representative in Honolulu, finds that green fluorescent lamps protect his roses against the depredations of night-working Japanese beetles. The use of light to retard the beetles has long been known, but Mr. Ramsay finds that green fluorescent tubes give the highest efficiency. He uses four 20-watt tubes which are operated by a time switch.

New Blackout Lamp.

A new blackout lamp, developed cooperatively by the Nela Park Laboratories of the General Electric Company at Cleveland, Ohio, and Army Engineers, eliminates the need for special shades and drapes, and yet gives ample light so that obstacles such as furniture can be clearly discerned. The lamp has a nominal rating of 14 watts at 115-125 volts and the interior is coated with an orange lacquer. The outside is coated with opaque black enamel, except for an aperture one inch in diameter at the bottom. This gives a controlled soft orange illumination. One lamp per room provides sufficient light to permit occupants to see one another plainly, as well as furniture, doors and windows. Obviously, it does not permit reading or the playing of cards. Orange is used, rather than red, so that the lamp will not be confused with exit lights.

Three Thousand-Watt Mercury Lamp.

A new 3,000-watt mercury-vapor lamp, the largest of its type in the world, has recently been announced by both the General Electric and Westinghouse Companies. The lamp is tubular, 55 in. in length and somewhat over an inch in diameter, and is rated at 120,000 lumens. It is more than eight times more powerful than its nearest rival, the 400-watt mercury lamp, and gives twice as much light per watt as the incandescent lamp. It is believed that the lamp will be particularly advantageous for lighting airplane factories, steel mills, foundries and other buildings having large areas and great height.

Blackout Street Light.

A new street lamp giving the light equivalent to that of a single candle has been developed in the illuminating laboratory of the General Electric Company for use during blackouts. The fixtures are spaced 100 ft. apart and are mounted 15 ft. above the street. The spread of light is equal to starlight or 1/100 of moonlight. The entire fixture is painted black and within it a 10-watt incandescent lamp is mounted and so concealed that the only illumination is through a circular narrow piece of plastic around the side. The first impression is that this lamp produces no illumination at all, but as the eye becomes accustomed to the light it is not difficult to see persons or objects at distances up to 30 or 40 ft.

Glareless Glass.

In the Research Laboratory of the General Electric Company a new process has been developed whereby the annoying glare caused by the reflection of light from glass surfaces can be removed. The glass-surfacing process, the development of which was conducted under the direction of Dr. C. W. Hewlett, produces a non-glare surface. The surfaces to be treated are placed in a large high-vacuum globe and then a tiny bit of magnesium fluoride is electrically evaporated, coating each surface with a film but 1/300,000 part of an inch. Surfaces treated in the metal globe can be handled without damaging the non-glare surface.

Sunlamps.

With the continuously diminishing supply of cod-liver oil and an increased interest in vitamin-D sources, there is an increasing demand for sunlamps. Two new types are of special interest. Both are of the reflector type, one with the usual sunlamp placed in the reflector-type bulb with an admedium base. The other is a 275-watt unit which combines an ultraviolet source and a reflector and also includes its own ballast equipment so that it may be screwed into an ordinary lamp socket.

Germicidal Lamps.

As a by-product of the 8-watt fluorescent lamp, a 12-inch germicidal lamp of this same wattage has been introduced. High transmission glass makes it more effective than its low wattage would imply. The compactness is of advantage in small sterile-storage cabinets. Such lamps are being used with apparent success in controlling the spread of respiratory diseases caused by air-borne bacteria, and they are being successfully used to prevent the growth of mold and fungus formations in many industrial processes.

Cathodic Lamp.

Another product of fluorescent-lamp research is a new special phosphor powder used in a near-ultraviolet lamp. This changes the short-wave ultraviolet energy within the lamp to harmless ultra-violet which may be used to activate the many fluorescent materials available. The low breakdown and operating voltages permit the use of the lamp with ordinary dry-cell batteries. When properly used in the cockpit of an airplane, the lamp makes it possible for the pilot to see the fluorescent instruments and maps readily, while a filter prevents tell-tale visible radiation escaping to attract attention to the plane.

Sodium Luminaire.

The General Electric Company has developed a sodium luminaire which has a built-in photoelectric control designed to operate the luminaire in accordance with natural-light conditions. That is, at twilight the cell causes the luminaire to be switched on and it is switched off when daylight approaches. A time-delay feature insures against operation because of such factors as lightning flashes and automobile headlights.

1941: Electrical Engineering

Wind Power Electric Generator.

On Oct. 19, 1941, a wind-power generating unit near Castleton, Vt., was phased and connected to the alternating-current power system of the Central Vermont Public Service Corporation. This is the first time that energy produced by wind power has been delivered into a central station transmitting and distributing system. At this time synchronized operation continued for two hours and a maximum of 800 kilowatts was generated at an indicated wind velocity of 26 m.p.h.

Alternators.

The inevitable vibration of rotating electrical machinery produces noise and such noise is disagreeable. Much of the noise comes from the double-frequency vibration that is transmitted to the floor or supporting structure to which the base of the machine is fastened. By spring- or resilient-mounting the stator core, the double-frequency vibration to the supporting structure of a 25,000-kw., 3600-r.p.m. turbine-driven alternator was practically eliminated. This is the first example of this type of mounting with a large commercial alternator. The alternator is installed in the Westport Station of the Consolidated Gas Electric Light and Power Company of Baltimore.

Dams and Dam Power Generators.

Early in August the waters of Lake Mead, storage for Boulder Dam, spilled over the dam for the first time. The lake has been filling for six and one-half years. Two electrical generators at Grand Coulee Dam, Wash., are now in operation, producing for the first time power from the water of the Columbia River impounded behind the dam, the largest masonry structure in history made by man. The generators, made by Westing-house, deliver 10,000 kilowatts each, stand 13 feet high and each weighs 88 tons. These generators are now feeding a line connecting the stations at the Grand Coulee Dam and Bonneville Dam, so that the Grand Coulee power now supplements that of Bonneville which is being supplied to important defense industries. The foregoing generators are mere pygmies compared with the three that are now being built and which should be installed next summer. These latter will have outputs of 108,000 kilowatts each, will be 24 feet high and 45 feet in diameter, the largest water wheel generators ever built.

New Power Line to Chicago.

In order to increase the power supply to the Chicago area, particularly to meet the present defense needs a new 147-mile, 220,000-volt, 3-phase power line, running from the coal fields of southern Illinois to Chicago has just been completed.

In order to control the line operation, as well as to establish communication channels, the line wires are also used to propagate radio waves. This is called a carrier system and differs from the usual broadcast system in that the waves are guided along the metal power-line wires rather than being radiated out into space. In this line three distinct frequency bands are used and these are modulated in such a way that eight distinct channels are obtained. It is most important that the carrier service be maintained continuously. Accordingly an alarm system is so arranged that the operators in the stations are immediately warned of any interruption of the service. The line now delivers 200,000 horsepower to the Chicago area.

Substation on Wheels.

In order to be able to meet sudden demands for power brought about by the present emergency, the General Electric Company has constructed a completely factory-built 1,000-kilowatt mobile substation for the New York Power Corporation at Syracuse, N. Y. The first of its type, the substation is mounted on a special chassis and can be hauled at speeds up to 40 miles per hour. The unit is 21 feet long, 8 feet wide and 11 feet, 6 inches high and weighs 10 tons. The equipment consists of a 3-phase, 1000-kilowatt transformer with primary and secondary switching equipment and lightning arresters. It can take power from high-voltage lines of 11,000, 13,200, 22,000, 33,000, and 44,000 volts and transform and supply it to systems of 230, 460, 2,300, 4,000 and 4,600 volts. It is thus very flexible. The substation can be used in an emergency, to restore power to customers when a regular substation or part of the system has been put out of service, to take the place of a substation when repairs are being made, and to supply power when an unusual demand has suddenly appeared, and which overload existing facilities. The substation is expected to be in use about 75 per cent of the time.

Power for New York Subway.

Underground trains require direct current for their operation. Power is ordinarily generated in large alternators in large central stations, as alternating current. There are several reasons for this condition. Alternators can be made in large units, as large as 200,000 kilowatts, so that generating economies not obtainable with small units can be obtained. Also alternating current can be transmitted long distances efficiently and the voltage can be raised and lowered economically by means of transformers. When direct current is needed there must be means for converting the alternating into direct current. In recent installations, 'ignitrons' are being favored over the multianode tank rectifier. The ignitron unit consists of a single cylindrical steel tank in which there is but a single anode and a single cathode. Several ignitron units are used in combination to form the converting unit, a common number being six. Until the ignitron is ready to fire on the positive halfwave, once every cycle, there is no mercury vapor in the tank. At the instant that the tube should be fired a voltage is suddenly applied by a 'peaking' transformer to the ignitor, a high-resistance point that dips into the mercury pool. The heat at the junction of the ignitor and mercury immediately converts the mercury into a conducting vapor which persists until the end of the half-cycle, when the arc goes out and the vapor again condenses into liquid mercury. This process is repeated every half-cycle. In the multi-anode tank, there is always mercury vapor in the tank, as one or more anodes are always firing, so that the possibilities of are back are much greater than in the ignitron in which there is no mercury vapor except when firing takes place.

In both the Village and Greely substations of the Sixth Avenue subway, two such 3,000-kilowatt, 625-volt ignitron units are installed to convert the alternating into direct current for driving the direct-current motors on the cars. Each unit consists of six single units or tanks.

Owing to the fact that synchronous converters were already installed in the Central and Greenwich substations, the power in these substations was increased by installing two more 4,000-kw, 625-volt synchronous-converter units in the Central substation and one more such unit in the Greenwich substation.

The foregoing installations are one of the first examples of ignitrons being used to convert a-c into d-c for subway train operation.

Transformer Iron Hipersil.

A new development in iron for transformer cores, Hipersil, was brought out during the year by the Westinghouse Electric and Manufacturing Company. This core material is basically new and can carry one-third more magnetic flux than ordinary silicon steel and thus effects major economies in transmission and distribution of electrical energy. An innovation in the manufacture consists of coating both sides of the strip with a microscopically thin glass that acts as a bond so that when the core is assembled it becomes a solid mass. With this assembly the direction of the flux is always in the direction of preferred grain orientation which produces minimum loss. The annoying hum emitted by transformers is due to 'magnetostriction', that is, under the influence of the alternating magnetism the iron alternately elongates and contracts, producing the well-known hum. This magnetostriction effect in Hipersil is only a small fraction of that occurring in steels used heretofore, and thus transformers using it are much quieter than transformers using standard silicon steels.

Solder Sealing of Bushings.

Solder sealing of bushings for transformers and circuit breakers has been made practicable by the Westinghouse Electric and Manufacturing Company. For years a major aim of the industry has been to eliminate the present gaskets, which are not hermetically tight and in time may admit moisture. Solder sealing gives full protection against such moisture.

Largest Induction Motor.

During the year the world's largest induction motor, having a rating of 40,000 horsepower, made by Westinghouse, was put in operation. It is used by the United States government to drive the fan blades producing the air velocity in a wind tunnel. The motor drives two fans 40 feet in diameter which create a 400 miles per hour wind velocity used in aircraft research. The motor is 15 feet in diameter. The rotor or armature is 10 feet in diameter and when removed, a small truck could be driven through the opening in the stator. The speed of the rotor can be varied from 39 to 297 revolutions per minute. The motor is the largest that can be built and shipped in one piece. Because the motor drives a screw-type fan, the thrust load is 75 tons, so that a Kingsbury bearing such as is used with water wheels is required for the rotor.

Lightning.

The General Electric Company continued the study of lightning in the tower of the Empire State Building. This lightning research has demonstrated the dependence of thunder on the type of discharge. Strokes to tall buildings where several initial leaders (small strokes which precede the main stroke) are present, occasionally are not accompanied by thunder because such strokes require several hundredths of a second to build up. The flashes which require only a few millionths of a second to build up, create very steep air-pressure waves and therefore are accompanied by loud claps of thunder. Other strokes consist of a series of discharges through the same path or multiple strokes as they are called. These strokes produce the so-called tearing or ripping variety of thunder.

Investigations conducted on power systems have shown that the wave shape of the lightning stroke is determined by the cloud charge, the rate of propagation of the leader strokes, and the availability of charges on the earth's surface at the point where the stroke hits. For example, lightning striking a well-grounded transmission system many miles in extent will have a much higher current magnitude than a stroke to a mountain, a non-conducting rock, or a dry sandy area.

Special study has been given to lightning protection for trolley coaches. Comparison of experiences with 29 different trolley coach companies indicates that at least 6 arresters per mile or 3 per mile of each trolley wire are desirable from a practical point of view.

Modern steel cars are effective shields against lightning, as has been recently proved in the High-Voltage Laboratories of the Westinghouse Electric and Manufacturing Company at Trafford, Pa. Dr. Gilbert D. McCann sat in an ordinary steel-top motor car while it was being bombarded by 3,000,000 volts of artificial lightning, produced by the lightning generator in the laboratory. In an actual storm, the wet rubber tires would increase protection since they would assist in conducting the electricity from the car body to the ground.

Nylon Magnet Wire.

Nylon has recently been put to a highly useful purpose. The Anaconda Company is using it for the insulation of magnet wire. For years, silk has been used for such insulation, particularly with the small sizes where the thickness of the insulation must be kept small. Sometimes enamel coatings are substituted for silk. However, Nylon magnet-wire insulation shows superior qualities to both. It has exceptional resistance to abrasion. At ageing tests conducted at 125°C., it shows no sign of failure; it does not deteriorate under the influence of humidity; it has high dielectric strength, and performs well under the combined effects of high temperature and pressure. When the material becomes more plentiful its use as magnet-wire insulation will undoubtedly expand rapidly.

Fluorescent Lamps.

Few if any industries have expanded more rapidly than the fluorescent-lamp business. Although in 1940 only 9,000,000 fluorescent lamps as compared with 900,000,000 large incandescent lamps were sold, the fluorescent lamp has shown phenomenal development and the growing public demand for fluorescent lamps testifies to their satisfactory operation in service. During the year the line was extended to higher-voltage sizes with a white 60-inch, 100-watt lamp giving one and three-fourths as many lumens per foot and a total of twice as many lumens as the heretofore 48-inch, 40-watt lamp. To meet the demand for a shorter lamp that would permit better-proportioned fixtures and still maintain a high lumen per foot of lamp, the new 65-watt, 36-inch fluorescent lamp was introduced in March 1941.

For applications where a spectral quality requiring a greater proportion of red is desired, lamps are available in a new 'soft white' color in the standard 18-, 24-, 36-, and 48-inch sizes. This new color should find use in places where food is illuminated in cases or where it is served. These lamps are also used where color complimentary to an individual's appearance is desirable.

A new development is the 'Troffer,' a trough-coffer combination in which continuous rows of fluorescent lamps are well shielded in lowered troughs recessed in the ceiling.

Queen Elizabeth Way.

The world's longest continuously lighted highway is the Queen Elizabeth Way in Ontario, extending from Toronto to Niagara Falls, a distance of 70 miles. A further extension of 20 miles to Fort Erie, opposite Buffalo, is proposed. This is a heavily traveled road through thickly populated areas. There are two concrete lanes, each 20-23 feet wide with a center reservation. Because of the low cost of power, incandescent rather than sodium lamps are used except at intersections where sodium lamps are used. The incandescent lamps are of the 6,000-lumen, 405-watt multiple type with a life of 3,000 hours. They are replaced on a semi-annual schedule.

Germicidal Lamp.

Latest in the germicidal lamp is a 30-watt source identical with the 36-inch standard fluorescent lamp except for the omission of phosphor and the use of a special glass which allows the bacteriological ultraviolet rays to pass through. The line also includes 4-, 5-, and 15-watt germicidal lamps. These lamps have found many new applications such as destruction of air-borne bacteria around infant cubicles, in hospital operating rooms. One large New York hotel is using them to sterilize bathrooms and a manufacturer has used them to reduce the number of bacteria in the cotton for filling mattresses.

Stroboscopic Inspection.

Stroboscopic inspection equipment recently developed by the General Electric Company for high-speed cloth-printing machines permits accurate study of printed patterns at high speeds and it can be applied to most cloth-printing machines without mechanical modification of the machine. Just as cloth leaves the printing machine it is necessary that operators check the location of the color on the finished pattern and also whether or not imperfections have occurred during printing. Heretofore it has been difficult to do this at speeds above 100 yards per minute. In the new method repeated flashes of light synchronized with the motion of the cloth make the pattern appear to be stationary, so that inspection is made at high speeds without difficulty. Moreover, since the pattern, as visualized appears to be stationary more precise inspection can be made than by the old method, even when the cloth moved at only moderate speed.

Mercury Searchlight.

The General Electric Company has completed a 1,000-watt search light with a 24-inch drum and silvered-glass reflector in which the mercury lamp is smaller in size than a cigarette. However, it is necessary to pump a gallon of water a minute through a glass water jacket surrounding the mercury lamp to carry off the heat developed. Another innovation is an auxiliary conical reflector, mounted in front of the mercury lamp to build up the candlepower of the unit.

New Electron Microscope.

The RCA Manufacturing Company under the direction of Dr. Zworykin, has completed a commercial electron microscope, which is simple and rugged and can easily be transported, installed and operated in the average research laboratory. The microscope, including the power supply and accessories is only about 7 feet tall and weighs approximately 500 pounds. It occupies small floor space, can be set most anywhere, and operates from the 110 volts alternating current that can be obtained from the ordinary electric outlet. The operator can sit conveniently in front of the instrument where he has ready access to all the switches and controls and at the same time, by looking through the eye piece, has the magnified image of the specimen under observation. He can control the brightness of the image, bring it into sharp focus, and control the magnification over a wide range. The control and vernier action is such that the position of the specimen can be adjusted to within two one-millionths of an inch.

By turning a suitable control, exposures of the image on a photographic plate can be made. The average time of exposure is 20 seconds. Also the controls, valves, and interlocks are so arranged that plates and specimens respectively, can be changed without breaking the vacuum. Although 60,000 volts is required and the voltage must be regulated to one part in 50,000 no bulky transformers, filters, or power packs are used.

With optical microscopes the limit of magnification is from 3,000 to 6,000 diameters. With the electron microscope magnification can reach as high as 100,000 diameters and 30,000 diameters are readily obtainable. The focusing elements are magnetic fields and electrostatic fields whose shape and intensity can be controlled. The electron microscope has already opened a new visual world to science. See also articles on MEDICINE; RADIO; TURBINES.

1940: Electrical Engineering

New Power Installations.

Several new hydroelectric stations have gone into service during the year. Among these is the Clayton station of the Appalachian Electric Power Co. (American Gas and Electric Co.), which involves four 20,333 kilovolt-ampere alternators. The entire station was designed with the modern architectural motif in view. For example the contours of the turbines and generators were streamlined, the color scheme of the station is attractive and the enormous block glass windows have a strong architectural appeal.

Two more 82,500-kilowatt units were placed in service at Boulder Dam making the seventh and eighth units, and work is now being conducted on the ninth and tenth units. Three 108,000-kilowatt alternators are being constructed for Grand Coulee. These are 48.5 feet in diameter, which is larger than the Boulder Dam alternators and the largest water-wheel-driven alternators yet constructed.

The first unit of the Bonneville Power substation on the Columbia River, located one mile north of Vancouver, Wash., has been completed and preparations are under way to distribute the power in that region. There are two 230,000-volt, 3-phase, 60-cycle incoming transmission lines from Bonneville Dam. There are plans for one outgoing 230,000-volt line to the Puget Sound area and six 115,000-volt lines to other points in Washington and Oregon.

The Michigan Electric Co. placed in service, late in 1939, at New Carlisle, Indiana, a 25,000-kilovolt ampere, 3600-rpm, synchronous condenser manufactured by the Westinghouse Electric & Mfg. Co. This is the first large-sized synchronous condenser built for the high-speed of 3,600 rpm. The high speed permits small size and weight. It is hydrogen cooled and its direct-current excitation is obtained by means of an ignitron (mercury-arc) rectifier. This is an innovation since heretofore synchronous condensers have commonly been excited from a small exciter consisting of a direct-current generator driven by or mounted on the shaft, or from direct-current bus-bars. A synchronous condenser is an alternator operating as a synchronous motor without shaft load. By overexcitation (dc) the synchronous condenser may be made to take a leading current just as a static condener or capacitor. By underexcitation it may be made to take a lagging current just as a reactor or inductance. Such condensers are essential to control the voltage on high-voltage transmission lines such as that from Boulder Dam to Pasadena.

Another 60,000 kilovolt-ampere hydrogen-cooled synchronous condenser was installed in the Chino substation of the Southern California Edison Ltd. This and a similar unit installed a year ago are used to control the voltage of the long incoming lines from Boulder Dam.

The three largest autotransformers ever built were installed on the system of the City of Los Angeles. Each covers a ground space of 24 by 12½ feet and each is over 37 feet high. The bushings are the largest yet in use, being 24 feet, 3 inches long. These autotransformers will step down power from the 287,000-volt Boulder Dam line to 138,000 volts, for local transmission. The autotransformers are rated at 65,000 kilovolt-amperes and have the remarkably high efficiency of 99.64 per cent. (See also WATER POWER.)

The Amplidyne.

Dr. E. F. W. Alexanderson, A. F. Fisher and M. A. Edwards of the General Electric Co. have developed a new type of power generator known as the Amplidyne, which is capable of operating as an amplifier of control impulses in much the same manner as the vacuum-tube amplifier acts, but the Amplidyne operates at much higher power levels. It responds almost instantly to changes in power input with no appreciable lag between input control and output response. A total amplification of 10,000 to 1 is possible. The Amplidyne consists of a motor-driven generator with an extra set of short-circuited brushes for each pair of poles, these brushes being at right angles to the power brushes. The control magnetic field is energized by a field winding, and this magnetic field induces a voltage in the short-circuited brushes with an over-all amplification of 100 to 1. The current in the short-circuited brushes, reacting through the armature, produces a further amplification of 100 to 1 at the power brushes, resulting in a total amplification of 10,000 to 1. There have been several installations of the Amplidyne generator, particularly in the steel industry, the object being to secure rapid and accurate positions of the tool in a boring mill, and to control the speed of reeling continuous steel strip. In the paper industry an Amplidyne operating in conjunction with photoelectric devices permits the production of light and heavy weights of paper, and in addition maintains the exact register of paper moving through rewinding.

Electric Power in Modern Transport Planes.

The modern passenger airplane requires 15 kilowatts of electrical power as compared with 2 kilowatts in 1929. Of this power 7.0 per cent is used for operating the ship, that is for controls, etc.; 73 per cent is used for navigation including radio and de-icers; the remainder is used for service, mostly lighting. Two generators attached to the engines provide the current at 12 volts for charging storage batteries. The tendency at present is towards the use of a 24-volt system.

Mercury-Arc Rectifiers.

Aluminum is made by electrolyzing alumina (Al₂O₃) in an electric bath of fused cryolite (a fluoride of sodium and aluminum, Na₃Al F₆). This process requires a large direct current in the neighborhood of 10,000 amperes at a voltage of from 6 to 10 volts per cell. Until recent years, the direct current (dc) has been supplied by direct-current generators and more particularly by synchronous converters which convert alternating current (ac) into direct current. For the past few years the mercury-arc rectifier has been superseding these rotating machines for conversion of ac to dc for such power purposes as direct-current power systems and railway electrification such as the Lackawanna Railroad. However, recently a large mercury-arc rectifier unit has been built by the General Electric Co. for the new reduction plant of the Aluminum Company of America at Vancouver, Washington. The complete unit is rated at 10,000 amperes, 600 volts, dc, and comprises 12-anode ignitron rectifiers with a main transformer and reactors. In the past mercury-arc rectifiers have been built with the three, six or twelve anodes in a single steel tank. With such conventional multiple-anode rectifier tanks the arc drop increases with the number of anodes and as a result the efficiency decreases. The ignitron rectifier is designed to overcome this disadvantage. It consists of a single-unit mercury-arc rectifier with one anode and one cathode. Since a single ac mercury-arc is not self-sustaining, a high resistance rod dipping into the mercury pool and energized at the proper instant every cycle, starts the arc each cycle.

The Allis-Chalmers Co. has devised a single-anode tank mercury-arc rectifier which differs from the ignitron in that a continuous arc is used for establishing the arc each cycle rather than an ignitron which produces intermittent excitation. The igniter-exciter which produces the arc does not need to be immersed in the mercury pool and the level of the pool is not critical. Grids and shields are designed to provide adequate deionization and baffling. For service below 1,000 volts dc the efficiency of this rectifier is substantially greater than that of the multiple-anode type.

Oil-Less Circuit-Breakers.

There is an increasing trend to the use of oil-less or air circuit-breakers for indoor service. The advantage of air circuit-breakers is the elimination of the fire hazard and the maintenance caused by the carbonization and deterioration of the oil. By the use of compressed air the interrupting capacities of air circuit-breakers have been carried to the unheard of value of 1,500,000 kilovolt-amperes, about twice the value obtained with European breakers. This is accomplished by using a blast of air at 150 pounds per square inch pressure driving the arc against a series of splitter plates. Records have been obtained which show an interrupting capacity of 60,000 amperes at 13,500 volts, single phase. The very high speed of operation is due to the fact that the air also serves to operate the breaker mechanism. This also improves the performance since there are no heavy springs to oppose the closing of the breaker. The operation of these breakers is very fast, there rarely being more than a half-cycle of arcing.

Also along parallel lines, experiments have been conducted with water as the extinguishing medium, which show that this type of breaker can be built successfully to interrupt 1,500,000 kilovolt-amperes. Both the air and water circuit-breakers are small enough to fit into the cell structure of oil-breakers of the same rating.

A new type of air breaker designed for from 2,500 to 5,000 volts operates on the principle of driving the arc by means of an intense magnetic field into a series of slots in a narrow dead-end pocket formed from non-gas-forming material. The ionized arc gas is caused to intermingle with the non-ionized gas, causing deionization and rapid extinguishing of the arc.

Oil Circuit-Breakers.

Many improvements have been made in oil circuit-breakers, resulting in decreased size, and increased rapidity in the operation of the operating mechanism. Such breakers have an interrupting time as low as 5 cycles. Also improvements have been made in accessibility which is advantageous both in the wiring and in maintenance.

Underground Cables.

The electric conductors in high-voltage power cables and in telephone cables are insulated with paper tapes. In the former the paper tapes are impregnated with an insulating oil while in the telephone cables they are dry. The continued operation of both types of cable depends on the integrity of the sheath. One of the greatest causes of sheath failure has been the imperfect die welds along the sheath. The sheath is formed by a ram or plunger acting in a press cylinder to force the hot lead through a die to form the cylindrical sheath. The imperfect die welds are caused by the oxides and impurities which form on the surface of the molten lead in the press cylinder and remain when a new charge is added. Hence the die weld formed between the old and new charges is weakened by the presence of oxides and impurities in the weld. The General Electric Co. has eliminated this difficulty by the following means: The new molten charge is kept under an atmosphere of inert air to prevent oxidization; it is introduced into the press cylinder as molten lead flowing through a spout that goes well into the bottom of the cylinder, and at the end of the spout there is a nozzle that imparts a swirling motion to the molten lead that frees the oxide from the surface of the old charge. The oxides being lighter than the lead rise to the surface and the cylinder is allowed to overflow so that the oxides go out into a flood ring at the top of the cylinder. A hydrogen flame playing into the top of the cylinder prevents oxide forming when the ram is withdrawn from the cylinder. Examinations of the die welds made with this new process show no imperfections.

Activated Carbon Tapes.

The most radical development in high-voltage cable construction was the description given at the Convention of the American Institute of Electrical Engineers at Swampscott by S. J. Rosch of the Anaconda Co., of an activated carbon tape adjacent to the conductor in impregnated-paper-insulated cables. One of the principal factors in the failure of such cables is the evolution of gas from the paper and impregnating oils under the conditions of heating and stress during service. Oxygen is particularly destructive. The gases form voids in the cable, ionization occurs in the voids resulting in a gradual disintegration of the insulation. The activated carbon absorbs these gases and experiments under service conditions show that the life of the cable is prolonged.

With the laying of a 5-mile length of 22,000-volt cable between Falmouth and West Chop, Mass, the Cape and Vineyard Electric Co. provided a new source of electrical energy for its customers on the Island of Martha's Vineyard, heretofore dependent on the 1,625-kw Diesel-electric station at Oak Bluffs. At Falmouth the connection is made with the Affiliated New Bedford Gas and Edison Light Co. which is the principal power source in southeastern Massachusetts and the Cape Cod area.

Insulated Wire.

The General Electric Co. has developed a radically new type of enamelled magnet wire called Formex. The wire is insulated with a polyvinyl-acetal type resin and is distinguished by the adherence, stretchability and great mechanical toughness of the film. A coil of Formex insulated wire that was stretched 20 per cent in length was then wound on a mandrel of its own diameter without the insulation cracking. Formex is superior to enamelled wire in abrasive resistance, in resistance to solvent attack and freedom from heat cracking. The wire has already found several applications, particularly in small motors.

Lightning.

In 1939 the Westinghouse Co. devised the 'fulchronograph' which consists essentially of an aluminum disc a foot in diameter around the edge of which are inserted 400 hard-steel fins each about one-half the size of a nail file. Every 1/25,000 of a second a fin passes a narrow coil through which the lightning current passes and the fins accordingly become magnetized. From the degree of magnetization of the several fins, which is determined in the laboratory, not only the magnitude of the current in the lightning surge can be determined but the entire wave can be plotted as a function of the time.

During the past year the Westinghouse Co. has installed several of these instruments in the top of high buildings and have obtained many interesting records of lightning discharges.

The research on lightning conducted by the General Electric Co. in the top of the Empire State Building continues and during the year a paper was presented describing the multiple nature of lightning strokes.

Illumination.

The general adoption of the sealed-beam headlight was an outstanding development in the art of illumination during the past year. No other major safety step in motor cars has had such a widespread initial adoption. Almost all 1940 cars are equipped with completely interchangeable sealed-beam headlights designed to the same optical specifications. There are two interchangeable forms, an all-glass unit in which the filament operates directly in the unit without a bulb of its own and a unit with a metal reflector in which the lamp with its bulb is permanently affixed to the reflector and the lens sealed to the reflector. The sealed-beam type of headlight has many advantages; higher light output with more coverage laterally and vertically; substantial reduction in glare to oncoming drivers and at the same time illuminating the right-hand side of the road to a greater distance; lighting efficiency maintained at a high value during the life of the lamp with new-car efficiency with the installation of a new unit; simple and uniform provision for aiming headlight readily carried out by car owner; uniform beam indicator; ready availability of renewal units through standardization of the interchangeable forms.

In fluorescent lighting a new white color was developed for all sizes of fluorescent lamps. In the newer equipment the lamps are shielded from direct view, direction or diffuse distribution being provided as desired. In previous units the auxiliaries included both ballast and automatic switch so that a faulty switch required opening the wire channel and replacing the complete auxiliary. In the later units the ballast and switch are separate and the latter is easily accessible so that it is readily replaceable.

A 6-watt, 9-inch lamp has been put on the marked designed particularly for air liners and Pullman berth. It is available both in white and daylight.

The tellurium lamp, a new type of electric lamp employing tellurium vapor, has been developed by the Westinghouse Lamp Works at Bloomfield, N. J. The actual light comes from a glass tube shaped like an inverted J, which is contained in a larger glass bulb. With a tube four inches long and a little more than a half-inch in diameter, satisfactory operation was secured with 2 to 3 amperes of current at 150 to 200 volts. The tellurium resembles a glowing solid more than a glowing gas and the light is close to daylight.

A new photoflash lamp smaller than a golf ball has been added to the line of flash lamps. It is designed for all purposes except focal-plane-shutter cameras and two dozen can be carried easily in a suit pocket. It gives a million lumens at the peak of the flash and it is provided with a bayonet-type base designed for rapid loading and unloading. (See also PHOTOGRAPHY.)

The 1,000-watt, water-cooled mercury lamp — the midget sun — of a year ago has been considerably improved as regards the water jackets and in the safety circuits and auxiliaries. The 100-watt capillary mercury lamp has been put into an ultraviolet transmitting bulb, making it an excellent sun lamp. It is expected to be very useful in the animal and poultry industry.

Street Lighting.

The highest level of illumination along urban business streets is now in Falls Street, Niagara Falls, N. Y. Twin light standards with 15,000-lumen series lamps are arranged opposite and on approximately 70-foot linear spacings with a mounting of 23 feet above the street. The average lighting on the pavement is more than 5 foot-candles, a sufficient intensity for the reading of ordinary sized type.

The world's largest and longest sodium safety-lighting system was turned on and dedicated in July. It constitutes the 33-mile Belt Parkway running from Owl's Head Park in Brooklyn to the Bronx-White-stone bridge in Queens. More than 2,200 lights developed by the General Electric Co. are used. The luminaires employ airplane-shaped reflectors and use 10,000-lumen lamps in a horizontal position. They are mounted 23 feet above the Parkway on cedar poles spaced 150 feet apart along a divided highway. Incandescent 230-watt lamps with orange-colored glass globes to harmonize with the sodium lights are installed in the ceilings of the underpasses.

Germicidal Lamp.

The General Electric Co. has invented a new germicidal lamp which differs materially from those heretofore in use in that it is inexpensive, of low wattage, and does not generate any great amount of heat. The lamps heretofore in use for germicidal purposes were either carbon or iron arcs or mercury arcs in quartz tubes and of relatively high wattage such as 250 watts. The new lamps are available in 3-, 5- and 15-watt sizes; about 95 per cent of their ultraviolet light is effective in killing germs. The 3-watt lamp is about 5½ inches long; the 5-watt is about 9 inches long and the 15-watt lamp is 18 inches long. These lamps have the same operating characteristic as fluorescent lamps and the 15-watt size can be operated in a fixture for an 18-inch lamp. A small reactor is in series with the 3-watt size and a resistance is in the base of the 15-watt size. An aluminum reflector is needed to reflect the ultraviolet light. An idea of the effectiveness of these lamps is evidenced by the fact that a 15-watt lamp will kill B-coli at a distance of one meter in 30 seconds. The uses of such lamps are many. They are used for sterilizing the air-ducts of air-conditioning systems; for the prevention of mould in food; for killing germs in soda-water glasses and dishes; to prevent rickets in poultry, and in hospitals.

X-Ray Equipment.

The most powerful and most flexible X-ray equipment of its type has been installed in the new high-voltage laboratories of the National Bureau of Standards at Washington, D.C. The outstanding feature is the means by which 1,400,000 volts, direct current, is obtained. The main high-voltage generator involves several new features. It consists of a ten-section cascade stack of oil-filled Herkolite cylinders, the base of each section securely bolted to the next and at each base there is a shielding ring. The entire stack is filled with oil. In each section there is a 140,000-volt (dc) unit consisting of a main transformer, a filament transformer, two kenotron rectifiers, and two 0.1-microfarad capacitors. The main transformer in each section has two tertiary high-voltage windings, one of which supplies the primary of the transformer in the next section and the other supplies the kenotron filaments. The entire assembly is 30 ft. 6 inches high including the corona cap and occupies very little floor space. Adjacent to the generator stack is a smaller Herkolite stack of the same height containing a high-voltage resistance potentiometer. The generator feeds potential to a third stack containing the X-ray tube, connections being made from the shielding rings on the generator to corresponding rings on the X-ray stack and also to the potentiometer stack.

New Electron Microscope.

The magnification which can be obtained by optical means is limited by diffraction and is from 3,000 to 6,000 diameters, depending on the specimen. Also the length of light waves themselves limits the size of objects which can be resolved by the ordinary microscope. A beam consisting of moving electrons, although it cannot be focused by means of glass lenses, may be focused by being passed through lens-shaped magnetic fields and a high degree of resolution thereby obtained. This is the principle of the electron microscope. The specimen must however consist of a very thin film through which the electrons may pass quite readily. The microscope consists of a long tube at a very high vacuum containing an electron source with the accompanying accelerating potentials (electron gun) and three focusing coils and the projection coil. The specimen is placed within the objective coil. After the beam passes through the specimen the objective coil produces a magnification of 100 times and the beam is then directed through the projection coil which produces further magnification of 250 times, making a total magnification of 25,000 diameters. At the bottom of the tube there is either a fluorescent screen on which the image may be viewed or a photographic plate to record the image. It should be pointed out, however, that in a sense the image produced by the electron microscope is a shadowgraph and may not disclose factors than can be revealed by the optical microscope.

1939: Electrical Engineering

Electrical Power and Machinery.

It has been previously reported that hydrogen was used for the cooling of turbine-driven alternators, the method first being applied to small units. Hydrogen cooling has now been applied to units with ratings as high as 150,000 kw. operating at speeds of 1,800 r.p.m. There are now 500,000 kw. in hydrogen-cooled alternators operating in the United States. As has been previously stated, the advantages of hydrogen cooling are that hydrogen is a much more effective cooling agent than air because of its much greater specific heat and penetrative qualities, and the windage loss with hydrogen is materially less than with air. Of particular interest is the 75,000-kw., 1,800-r.p.m., hydrogen-cooled generating unit constructed by the Westinghouse Co. for the Duquesne Light Co. and located in the James Reed Station on Brunot's Island in the Ohio River near Pittsburgh. In view of the recent severe floods the generator has been made flood-proof at standstill, so that in case of flood the generator will be stopped, a few adjustments made, and it will not be affected by submersion.

A synchronous condenser is a synchronous motor operating without load (mechanical). By varying the direct-current field excitation, the condenser may be made to take a leading, in-phase or lagging current as may be desired. Hence, its power factor can always be controlled. By connecting such condensers to power systems, the system power factor may also be controlled. This control has several advantages. The system may be made to operate more efficiently because of the leading current of the synchronous condenser counteracting the lagging current of induction motors and other induction apparatus. The voltage at the receiver end of transmission systems may be controlled and the stability of such systems be greatly increased by proper adjustment of the power-factor made possible with the synchronous condenser. Hence more power can be transmitted over a line without fear of the system 'dropping the load.' Without synchronous condensers, present long-distance transmission systems, such as that from Boulder Dam to Los Angeles, would be impracticable.

This past year a 25,000 kilovolt-ampere, 60-cycle, hydrogen-cooled, synchronous condenser, departing radically from past designs, has been constructed. The speed is 3,600 r.p.m., and the condenser is constructed like a turbo-alternator with a smooth, cylindrical rotor. Instead of the direct current for the field being supplied by a direct-current generator exciter connected to the shaft, as is usual, a mercury-arc rectifier with an electronic regulator controlled by electronic devices is used. This eliminates the rather unsatisfactory 3,600 r.p.m. exciter, and since the rectifier and regulators are electronic their inertia is small and their response virtually instantaneous.

In power transformers, oil is used for two purposes, to carry the heat away from the windings to the case from which it is dissipated to the outside air; to add to the insulation of the transformer, particularly where the voltages are high. Until recently mineral oil was used exclusively for this purpose. Since such oil, when ignited above the flash temperature, is highly inflammable, it is required that in industrial locations oil-cooled transformers be installed in fire-proof vaults, so constructed that should the transformer case burst, the oil could not escape from the vault. To obviate the fire hazard of oil, General Electric developed a synthetic liquid Pyranol, which has all the desirable properties of transformer or mineral oil; but in addition is non-inflammable, non-explosive, non-oxydizing and chemically stable. The Underwriters Laboratories have approved the installation in factories and other industrial locations of transformers using Pyranol, without the restriction of fireproof vaults. This is a great advantage in many cases; for although Pyranol is more expensive than oil, there results a saving in the construction of the vault, and the transformer can be located near its load, resulting in a material saving in copper and conductor losses. This is particularly true of welding, where the voltage is low and the current high. In the year 1939 the use of Pyranol-cooled transformers has been widely expanded both in voltage and power ratings, as well as in applications. For example, a 12,000-kw., 44,000-volt to 200-volt unit for furnace application has been put in service and a 625-kw., 11,000-volt transformer is used in railway locomotives to eliminate fire hazard, particularly in tunnels. These are examples of the wide uses to which Pyranol-insulated transformers are being put.

Lightning Generators and Lightning Protection.

Radical improvements have been made in high-voltage testing transformers and in surge or artificial-lightning generators, such as were used for the General Electric demonstration in Steinmetz Hall at the World's Fair. To produce the colored (red, green and blue) 1,000,000 volt, 3-phase, 60-cycle arcs, three cascaded transformers were required for each of the three phases. Each transformer was rated at 1,000 kw., 350,000 volts. One transformer was set on the ground; and the other two, connected in series with this one, were set on insulating cylinders so as to give the 1,000,000 volts above ground without subjecting any one transformer to more than 350,000 volts between its winding and case. The insulating cylinders are of paper impregnated with a resinous varnish, Herkolite, the paper being rolled into a hollow cylinder with hard solid walls. The colored arcs are produced by placing different salts in each of the three electrodes.

The design of the 10,000,000-volt lightning generator is radically different from previous designs. The condensers or capacitors using Pyranol (an artificial insulating liquid) with paper for insulation, are stacked on Herkolite (an insulating varnish) cylinders, each pole of the generator consisting of three stacks each several feet high with cross-connections for the resistors and for connecting the capacitors in the three stacks in series. This construction simplifies the connections and makes a neat and compact generating unit. The mode of operation is to charge the capacitors in parallel through high resistances (the resistors). When the capacitors are charged, a 'trigger-gap' flashes over; and discharges across a series of ball gaps follow almost instantly, connecting the capacitors all in series and producing the very high instantaneous flash or lightning discharge.

To protect transmission lines effectively from surge due to lightning and other surges, lightning arresters are used. Lightning arresters correspond to safety valves in a steam boiler. If the voltage rises, as may be caused by a lightning stroke or switching surge, the arrester prevents excess voltage by providing an easy path for the lightning to take to ground; but the arrester cuts off the arc which the power of the system tends to maintain as a follow-up of the lightning discharge. Theoretically, lightning arresters should be connected at every vulnerable point, as at every insulator and transformer. However, owing to expense, this is not practicable. To meet such a need, protector or expulsion tubes have been developed which are so inexpensive that they can be applied at a large number of the transmission towers, particularly those in lightning districts. Practically these tubes are only a sealed hollow fiber tube with a metal electrode at each end. The heat of the discharge liberates gas from the walls of the fiber, which intermingles with the ionized gas of the discharge, and cools and deionizes it, thus suppressing the arc. The tubes are connected, one end to ground and the other in series with a gap to the live conductor. Usually two tubes are used, one with an end connected to ground and the other with an end connected to the live line, with an intervening gap between the two free ends. Obviously such tubes are inexpensive, and it is practicable to apply them in considerable numbers to a system. During the year these tubes have been applied in increasing numbers and their characteristics and degree of protection studied by transmission engineers.

To be most effective, a lightning arrester should be connected close to the apparatus which it is to protect. The Thyrite (General Electric) and New Autovalve (Westinghouse) arresters are relatively compact and inexpensive. This has made it possible to incorporate the arrester as an integral part of the transformer that it is to protect. The transformer and arrester are now sold as a unit.

Fulchronograph Lightning Recorder.

The study of natural lightning continues. Until now, our knowledge of lightning was obtained with a cathode-ray oscillograph which, by means of an electric beam, records the voltage of a lightning stroke, and surge-crest ammeters, which consist of small pieces or links of iron which, when placed near a conductor carrying lightning, became magnetized by the current in proportion to the crest value of the current in the stroke. The surge-crest ammeter gives no information as to the variation of the lightning current with time. Hence there was great need for an inexpensive apparatus which would give this further information. The Westinghouse engineers have produced such a device, which traps bolts of lightning, studies their characteristics and then discharges them harmlessly to ground. It is called a fulchronograph and consists of vanes of permanent-magnetic material mounted radially on a wheel, which rotates the vanes through two coils which carry the lightning current. From the magnetism induced in each vane by the current of the lightning stroke, the magnitude and wave shape of the current can be determined. In a normal lightning season of 200 days the wheel makes approximately a billion revolutions. The instrument is now installed atop the 42nd story of the University of Pittsburgh's Cathedral of Learning. The first direct stroke recorded showed a 21,000 amp. crest followed by a low-amplitude component of 18,000 microseconds' duration. The current had decayed to 100 amp. in 0.02 second, which is a much longer time than previous records had given as the duration of a lightning stroke.

Three fulchronograph lightning recording stations have been established on the lines of the Appalachian Electric Power Co., a subsidiary of the American Gas and Electric Co.

Dr. J. M. Meek of the University of California discovered that lightning strokes travel through air at a velocity of 1,000,000,000 cm. per sec. (22,000,000 miles per hour). The initial act of the lightning discharge is to create a 'pilot' streamer of comparatively low velocity, which nevertheless speeds along at 20,000,000 cm. per second, which is followed by the later discharge.

Transmission and Distribution.

Work on the first phase of the Ross Dam on the Skagit River by the City Lighting Department of Seattle, Washington, is now being completed. There are ultimately to be three dams, developing a total of 1,120,000 horsepower. The Ross Dam is farthest upstream of the three and will be 655 ft. over all. The cost of this particular development is $5,600,000, 45 per cent of which is PWA funds; the ultimate output will be 360,000 kw. The two lower plants will have a capacity of 240,000 kw. each. This dam will create a 3,000,000 acre-foot reservoir, equivalent to 600 days' flow of the river, giving complete storage for power and flood control.

The construction of the third 287,000-volt, three-phase line from Boulder Dam to Los Angeles is now under way, assuring an added source of power to the Pacific Coast. The line conductors are the General Cable's 1.4-inch, type-HH, hollow conductor built up of ten segments to form a smooth copper tube.

High-voltage underground cables have hitherto been insulated with paper tapes, wound spirally about the conductor and impregnated with either heavy mineral oils (called the solid type) or a light viscous oil that flows in and out through the hollow core to a sylphon or accordion-like drum, with contraction and expansion (called the oil-filled type). Such cables are, of course, enclosed in a lead sheath. A new development is the gas-filled cable. The bulk of the oil is drained from the paper, and the cable is filled with an inert gas at 10 pound pressure. Although this cable does not have the life of the oil-filled type, nevertheless it has a longer life than the solid type, and the cost is much less than that of the oil-filled type.

The Magne-Blast Air Circuit Breaker for 5,000-volt service has just been developed by the General Electric Co. Usually for such service, oil circuit breakers are used because they are compact; the oil extinguishes the arc readily; and there is no exposed flame (except in case of accident). However, air circuit breakers are coming to be used more and more as they are justified by performance. Their advantage is small deterioration of materials, economical operating life, and no fire hazard due to explosion and burning oil. In the Magne-Blast breaker, specially shaped contacts are used. When the arc is drawn out between the contacts, a blowout coil, energized by the current, forces the arc into an arc shute of insulating material which is formed of corrugated members. The corrugations of these members inter mesh so as to form a serpentine path for the arc. The arc is thus extended and cooled and is rapidly extinguished. These breakers have given very good results in service, and tests show that they can interrupt 100,000 kva, at 5,000 volts, 60 cycles, 3 phase in 4.3 cycles.

Illumination.

In the field of illumination progress is still being made in lamp improvements. Until recently the largest size lamp made for the ordinary screw base was 200 watts. By improvements in manufacture and by the use of a heat-reflecting mica disc, the size has been increased to 300 watts. This enables the larger lamps to be used without changing sockets and wiring in existing installations. Instead of using screw sockets, the larger lamps are now of the plug-in type (known as bi-post base). This type of lamp can now be obtained in the 250 and 500 watt sizes. The advantages of bi-post construction are more precise focussing, one plane filament, smaller size of bulb that can be exposed to weather because hard glass can be used, improved fixture construction, smaller fixtures, and high over-all efficiency because of the better grid to collect the tungsten deposit.

The high-intensity, mercury-vapor lamp is being made in more different forms. The 100-watt lamp consisting of a discharge an inch long and one-twelfth inch diameter in a quartz tube has become standard for different purposes, such as in combination with tungsten lamps to produce daylight; in red-purple glass that transmits long-wave ultra-violet light to produce 'black light'; and in a special clear glass that permits the transmission of 'sun rays.'

Further research has developed high-pressure mercury arcs that have a brightness of 30,000 candle-power per square centimeter, 1,500 times brighter than the ordinary 100-watt lamp or one-fifth the brightness of the sun. It is the most concentrated commercial lamp ever developed. The lamp has a core of light smaller than a toothpick in a quartz-surrounded atmosphere of mercury vapor at a pressure of 100 atmospheres. The lamp is water cooled and operates at 840 volts. Its high actinic rays and intensity make it useful for photo-engraving work, searchlights and landing-field lights.

The efficiency and reliability of Cooper-Hewitt mercury tubular lights have been materially increased. This has been done in part by the use of reactor ballast in place of resistance and by improving the resulting poor power factor by the use of a Pyranol 3-microfarad condenser operating with each lamp. A starter with tungsten contacts increases the reliability and speed of starting the light. The new bare 350-watt lamp (tube alone) gives 19.4 lumens per watt, and with the fixture 16.0 downward lumens per watt. A combination unit of a 275-watt Cooper-Hewitt lamp and four 150-watt incandescent lamps (to correct for color) gives a total of 8.5 lumens per watt and 8.2 downward lumens per watt.

In Oklahoma City's Civic Center an innovation in municipal illumination is now in operation. The lighting units consist of a mercury-arc and tungsten-lamp combination. In order to emphasize the white limestone of the buildings and the green shrubbery, as well as to provide a high intensity source of illumination, 400-watt mercury lamps were selected as the primary units; and two 100-watt incandescent tungsten lamps in combination are used for color correction. A capacitor for power-factor correction is also incorporated with each lighting unit.

Fluorescent lamps ordinarily operate with a lagging current and the resulting low power factor is disadvantageous, particularly to the power system. The General Electric Co. now makes a unit in which two tubes are combined, one of which takes a lagging current and the other a leading current; so that the two practically compensate, making combined power factor 95 to 100 per cent. Another advantage is the reduction of the 'stroboscopic' effect or flickering. The maxima of the flicker in one tube occur when that in the other tube is a minimum, so that the total light emitted by the two is essentially constant.

Sterilamp.

In a former article (1938) reference was made to the Sterilamp of the Westinghouse Company, the rays of which destroy bacteria. This lamp has also been found most useful in connection with refrigeration. Meat, fruit and vegetables, even when in cold storage, after a few days develop mold growth. By placing Sterilamps in the refrigerator, the mold growth does not develop. For example, grapes usually develop mold growth at the end of five days and are unsalable after twelve days. Stored with a continuously operating Sterilamp, they were in perfect condition after five weeks. Bananas were the only fruit on which the lamp had any undesirable effect. The skin became darkened although the fruit was not otherwise impaired. With the Sterilamp meat can be stored at a higher temperature, and hence 'ripen' etc. without deterioration due to the growth of mold. See also TELEPHONE; TELEPHONE, INTERNATIONAL.