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.