Патент USA US2115777код для вставки
May 3, 1938. T, s_ JOHNSON ELECTRICAL CONDUCTOR 2,115,777 ' Filed May 8, 1936 Mefo?/c Colo/oer 1 CUIOF/C QX/c/e ‘ Layer -——,—-—5 C 0%,?“ 2 INVENTOR. 717/0’? ,5: n/é/wvso/v. ATTORNEYS 2,115,777 Patented May 3, 1938 UNITED STATES PATENT OFFICE 42,115,777 ELECTRICAL CONDUCTOR Thor S. Johnson, Irvington, N. Y., assignor to Anaconda Wire & Cable Company, New York, N. Y., a corporation of Delaware Application May s, 1936, Serial No. ‘78,559 3 Claims. (c1. 148-6) My invention relates to uninsulated electrical ther enhanced by using somewhat roughened rolls, conductors such as busses or other switchboard although smooth rolls will still permit a much less re?ective surface, aside from the darkened color, apparatus carrying heavy currents. Copper busbars are commonly used in sub-sta 5 tions and other switchboard installations in a wide variety of shapes and cross sections such as ?at, rectangular, round or channel, with a view to obtaining the greatest current carrying capacity forthe conditions of installation. The current 10 carrying capacity of such conductors is limited by the temperature rise, the usual limit of permis sible temperature rise generally ming 30° C., above the surrounding air temperature of 40° C. The maximum capacity will therefore be a our 15 rent having an energy or resistance loss which will be dissipated by a temperature difference of 30° C., over the ambient air. The current carry ing capacity of the busbar or other conductor is therefore governed not only by its conductivity and cross sectional area, but also by its ability to ' 26 dissipate heat rapidly. ' ' Heretofore copper busbars and other con ductors have been given arhighly polished smooth surface as, for example, by a cold drawing proc 2-5 ess or other means. The busbars retain their light color and smoothness with little change through age or use. The heat generated by the passage of the current through such conductors is given off to the surrounding air by conduction and con “ vection and is given up by radiation. In my in vention the radiation of heat from such conduc than would be obtained without the super?cial oxide coating. The outer layer of the oxide will 5 be a cupric oxide which may merge into a red cuprous oxide which, in turn, merges into the un oxidized metallic copper. This results in the for mation of a ?rm, lasting bond between the copper oxide and the underlying metal. 10 The invention is illustrated by way of example in the accompanying drawing which shows, in perspective,» a busbar of channel shape treated ac cording to’ my invention to provide a black ad herent copper oxide, parts of the oxide coating 15 being shown as removed to show position and arrangement. - ' In the conductor shown in the accompanying drawing, the metallic copper structure I is cov ered by a layer of oxides 2 in which the red cu prous oxide predominates. This is, in turn, cov ered with a layer 3 in which the black cupric ‘oxide predominates or composes the entire layer. These layers adhere closely to each other and to the underlying metal forming one integral struc ture. The oxide- coating’ is a permanent one, highly resistant to change, particularly in a dry atmosphere and, being completely oxidized, is un- affected by oxygen or by heating. v " Inasmuch as the amount of heat given off by 30 radiation for any given temperature is directly proportional to the emissivity of the surface, a - amount of current may be carried by a given‘ perfectly black body has the most radiating ef fect or emissivity, and the‘black voxide coating. conductor without exceeding the maximum tem closely approaches this ideal. For example, un- 35 35 perature rise. ' tors is very greatly increased .so that a larger In accordance with my invention I form on the surface of the conductor a non-polished or rough ened dark or black ?nish integral with the bus bar structure, thereby increasing the radiation ef ‘ 40 fects or efficiency over what can be obtained by a light colored highly polished surface. This black or darkened and roughened surfaceis obtained der a given set of conditions in which a polished copper‘su'rface dissipated heat at a rate vof 0.0027 watt per square inch when freshly washed, the rate of dissipation of heat increased to- 0.0029 after being tarnished in service,'whereas a similar 40 conductor treated according to my invention showed a heat dissipating capacity of 0.0038 watt ‘ by a superficial oxidation of the surface, of the ' per square inch, an increase of about 30%. The busbar preferably accompanied by a working of 45 the oxide thus formed on the surface of the metal. For this purpose the copper is heated to a sum ciently high temperature to cause a super?cial _ oxidation, and is, then rolled in suitable rolls .whichmay serve to give the‘busbar its final shape 50 and dimensions. This is in contrast to the cold rolling heretofore used which imparts a bright burnished surface to the metal. The super?cial oxidation forms a roughened or matte-like surface which also serves to increase 66 its radiating properties. ‘This may be still fur formation of the black matte 'or roughenedv sur- 45 face as an integral part of the conductor has the advantage over the exteriorly applied coatings or surfaces in that it is not affected by age nor by deterioration, and incurs no maintenance expense or difficulties. 50 While the invention has been shown as applied to achannel-shape busbar, it will be understood that it may be applied to any of the usual cross sectional shapes such as bar, rectangle, circular or special forms, the invention being in the -sur- ‘5 2' ' w I ‘2,115,777 face formed on such structures and not in the per electric conductors which‘ comprises oxidizing shape of the structure itself. the surface thereof to cupric oxide, and then hot What I claim is- . working said surface. 1. A method of ?nishing the surfaces of cop 5 per electric conductors which comprises oxidizing the surface thereof to cupric oxide, and then hot rolling said surface. _ 2. A method of ‘finishing the surfaces of cop _ ' 3. A copper electric conductor having a black matte surface of cupric oxide and an underlying 5 layer of cuprous oxide hot rolled into an integral structure with the underlying metal. THOR 8. JOHNSON.