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 Unused cables in the ground are being put into lower-voltage service, abandoned cable is being withdrawn and salvaged.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.