1348 I R O N A N D S T E E L I N D U S T R Y Journal A . I. E. E.

4. The breaker shall be capable of completing 100 normal operating cycles before any inspections or ad­justments are necessary. (If requirements 1 and 2 are met successfully, there should be no trouble in reaching 1000.)

5. The breaker shall be so designed that it can be installed, adjusted and maintained by the average mechanic without especial training in oil circuit breaker technique.

The growing knowledge of the important part played by the oil circuit breaker in a transmissiion network is stimulating investigations on the part of the operating companies to satisfy themselves as to the best circuit breaker for use on a given system. As has been previously stated, it is economically unfeasible for each manufacturer to maintain equipment for the testing of oil circuit breakers with a rating of 2,000,000 or more kv-a. at 220,000 volts. Also these tests at the manu­facturers' plants are not conclusive for it is impossible to duplicate the conditions met on an extensive, inter­connected transmission network, where recovery voltage, resonance, surges, etc., are variable and indeterminate.

The only way in which it is now possible for an operat­ing company to satisfy itself of the suitability of any theory of circuit breaker design, is to conduct carefully supervised tests on its own system. This requires a

maximum of courage, but if reliable service is the utlimate goal, all equipment must be tried and found not wanting. Competitive designs and theories, coupled with a wide range in price quotations, all in the face of a positive refusal to give any guarantees on performance, make the selection of an oil circuit breaker for a given installation extremely difficult. Present day knowledge must be amplified by further test data.

It is entirely possible that the oil circuit breaker as now known, may not be the ultimate device for opening a-c. circuits. They are used today because they are the only devices which have been developed to the point where a reasonable dependence may be placed on their operation.

The immediate problem is to combine in one oil circuit breaker all of the good features now available in the designs of the several manufacturers. By so doing it will be possible to approach the operating require­ments set down previously, and secure a breaker superior in performance to any now offered. Along with this must go continued research, looking toward the development of a device for the interruption of a high-voltage, alternating-current circuit which will be as dependable in its operation as is the transformer and generator. Pending this time, oil circuit breakers must be purchased and used with a full knowledge of their limitations.

Iron and Steel Industry Annual Report of Committee on Applications to Iron and

Steel Production* To the Board of Directors:

The importance of electricity to the production of iron and steel has reached such magnitude that this Com­mittee believes that all engineers should be informed as to the situation so as to be prepared to apply it success­fully in all its fields of application. To this end, the Committee would outline the extent to which electricity is being applied in this industry.

LIGHTING

Perhaps the first application was that to lighting. The arcs were replaced by incandescent lamps and now illumination is receiving much attention as to the proper lighting of various jobs and work spaces. Proper illumination is now credited with increase in both

•Commit tee on Applications to Iron and Steel Product ion

A. G. Pierce, Chairman, 1239 Guardian Bunding, Cleveland, Ohio A. C. Bunker, S. L. Henderson, J. W . Speer, A. C. Cummins, R. H . Keil, G. E . Stoltz, P. B. Crosby, W . C. Kennedy, T. S. Towle, J. H . Hall, A. G. Place, J. D . Wright.

F. O. Schnure.

Presented at the Summer Convention of the A. I. E. E. at

Detroit, Mich., June 20-24, 1927.

production and safety. Steel mills, however, are not yet lighted as they should be, and increased emphasis should be placed on this phase of their work by electrical engineers.

H E A T I N G

The use of electricity for heating has increased with the installation during the past year of over 25 melting furnaces. These range from }4. ton to 25 tons, and are of the arc type. The time of melt has been reduced considerably. The increase of production has also been greatly influenced by furnace design. The removable roof type of furnace appears to be the trend in design.

Resistor type furnaces are being used for annealing and for heat treating of alloy steels. Laboratory fur­naces have been used in the steel mills for many years.

Several years ago electrical heating was applied to rolls in sheet and tin mills to increase production during the first turn after a shut down or a roll change. This use is apparently well grounded since a report by the A. I. & S. E. E. states that 168 roll heaters are in use in 19 plants. Electrical heating devices have been used in crane cabs and offices for many years.

Dee. 1927 I R O N A N D S T E E L I N D U S T R Y 1349

M A I N R O L L D R I V E S

During 1926 nearly 150 main roll drives were pur­chased, all of which were electrically operated. Of these only six were a-c, the rest were d -c , ranging from 230 to 900 volts. Of a special interest is the 8000-h. p., 700-volt reversing, d-c. motor drive for the 54-in. blooming mill in a Pittsburgh mill. Large motors for such drives have become common. Individual motor drives on tandem strip mills are also of interest because of their increased use. While the use of d-c. motors has predominated, a few induction motors have been installed with speed control; also, a few large syn­chronous motors have been applied with apparent success on their particular mills. Undoubtedly, the use of synchronous motors for mill drive will increase.

To reduction of labor and the actual improvement in the steel produced is due the importance of the electri­fication of steel mills. Electric drives in steel mills permit the mill designer to produce a mill that will do things heretofore impossible.

A U X I L I A R Y M I L L D R I V E S

In connection with the installation of many new main mill drives, auxiliary drives have come in for much attention, with the idea of giving closer control of these auxiliaries with fewer operators. Automatic control of screw-downs, tables, transfer cars and drag-overs, together with furnace doors and pit covers, has increased with resultant efficiency, the ratio of steel production to men employed.

The A. I. & S . E. E. has completed its specifications for auxiliary and mill motors and one motor manu­facturer has announced motors built according to these new specifications.

Alternating current is gaining some ground applied to auxiliary drives, but direct current is apparently very well grounded in the steel mill electrical man's scheme of operations.

W E L D I N G

Electric welding can be mentioned briefly because it is used extensively for repair work, and indications are that in the future building construction will be in­fluenced by this process.

Perhaps the most important application of electric welding is its use for the building up of large machines by welding plates. These welded structures are to replace castings. The ease with which complicated as well as simple structures can be made, together with their lightness and strength, is making this innovation one of importance and one which gives promise of rapidly increasing use.

S A F E T Y

Because of the wide-spread use of electricity in mills, the various electrical departments appear to be leaders in safety programs and the elimination of all hazards as well as those electrical. This may be because of the peculiar nature of electrical hazards, and the extensive

steps taken by power companies and electricity users to eliminate these hazards and to take care of unfortunate victims. The prominent place of steel mill electrical men in the promotion of safety should be recognized.

M E A S U R E M E N T S AND INSTRUMENTS The metering of electric power has been practised

from the first, and its convenience has caused its more extensive use in the mills in order to determine not only the total power costs; but also the detailed operating costs down to individual machines and drives. Even auxiliary drive controllers are being specified to include permanent shunts for convenient metering. This permits proper distribution of costs for different processes.

Electricity also plays an important part in other than power measurements, such as tachometers and pyrom­eters for speed and temperature determinations. The metering of gases is done also readily with great con­venience by electrical means.

By the increased use of electrical power measurements attention has been called to economies that are possible. These economies are watched by all departments and stimulate effort by department heads to make savings heretofore uncontemplated. Furthermore, these mea­surements and economies stimulate improvement of design to effect even greater economies.

CONCLUSION

In conclusion, it may be noted that there is con­siderable activity in the rebuilding of steel mills so as to produce more steel at a lower cost. The old steam drives are replaced by electric drives, most of which are for direct current.

The transmission of electric power at high voltages, together with the ease with which it can be converted for convenient application, has caused the use of electricity to drive out steam. Its use is now amply safe-guarded and engineers and operators are more skilled in its application and use. The ease with which a few mill operators can control a large number .of motors through remote- control devices further demon­strates the superiority of the electric drive This rapidly increasing use of electric power demands the closest attention of electrical engineers.

The improvement in engineering that is apparent today gives a certainty of predetermination of results which is not only gratifying to the engineer, but of greatest value to the executive.

About 23,000 acres in McCurtain County, Okla­homa, are to be covered by a lake to be created by the building of four dams on the Mountain Fork River, where a paper pulp industry is developing. On the Colorado River in Texas, near Kingsland, and between Austin and Lampasas, six power dams are to be erected to impound water enough to generate 122,000 horse power of electrical energy.