US1574993A - Bus bar - Google Patents

Description

March 2, 1926.

1,574,993 D. F. MINER BUS BAR Filed Sept. 24, 1920 Fig.1 Fig- E C I E E 0 Ampere;

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" switchboard structures 3 i-DoUe As is: ivi Nnit, or -WILKINSBURG, I nousnnnncrnroai MANUFACTURING vANIA. -r j I ".A ptlica tion filed. September -;{.Be' it k own that I, Doue'LAs. F. MINER, a A citizen of theiUnitedIStates; and a resident 0t Wilkinsburg, .in the county otAllegheny 5 and State of Pennsylvania, have invented a new and useful Improvement in; Bus Bars, 1 of which the ,followingis V a" specification." My invention relates .to electrical f con- .ductorsj and gparticularly to; bus bars for g One object :o'flmy -'nventio n is to provide 5 'aiconductor' }that;.shall;be -so shaped as to compensate; for the {-skineiiect thereof to effect thereby 'a unifornr distribution oi- 1 current "thlerethrough', eliminate undue heat ing and, utilize "the conductor eliectively and .ec ono nical1y.

Another object. of my invention is to pro-,

.videi a ,bus-bar, "orf a, [similar conductor, and g a spacing vorsuppo'rting {member thereforj that shall be'sofforined and related as to provide a ventilating'space therebetween.

' henalternating-current passes through :a conductor, a periodically expanding and collapsing inagnetic fieldisfset up in and "around the conductor. This field induces a Y grcounter-electromotive force in the conductor j which produces'what isknown as skin effect:

j The apparent resistance of a given conv .ductor-to alternatingcurrent, divided'by its resistance to :direct. current, is known asthe 7 skin effect ratio for. the particular condi-' tions an e {the frequencyfof the alternating current considered]. {With alternating 1 currents of relatively high valuesfthe' skin efi'ect causes serious unequal, distribution of current throughout the cross-sectional arealof .the. conductor, causing. "relatively; greater current density P atthe. outer portions than, at} the central fportions' of the conductor." Thus,,the cen-,

5 tral portion is: underworked and the outer j portions areoverworked', resulting in an 1nefficient and unecono'micalfuse' of material 5 for a'givenlirnitation oftemperature oi the conductor; v a i ln'pra'ctic ng my lnY6Ilt10Il,-I provide a .conductor that is formedyas by rolling or drawing, toconfOrm to the distribution of,

currentJat standard frequencies, thus elimi- "f natingiundiue heating, and permitting the efficient and economical; use 30f copper or other conducting materialg' In my cope'n'dingapplication,"Serial No.

PATENT "0mm PENNSYLVANIA, ASSIGNOR To .WESTING- COMPA A CORPORATION or PENNSYL- BAR. it

24, 19 2'o. Serial No.41a529.

r 410,896, filed Sept. 17, 1920, teale444 structure for accomplishing similar results, as ,thoseherein set.forthtbyaddiirg magnetic metal members to theyconductors instead; of j by. shaping the latter in, special manners. Other devices appertaining to the distribution of current in conductors" are set forth in my copending applications,

Serial No. 412,530, filed Sept. 24:, 1920, and

.SerialNo. e12,531,,filed Sept. 24i, 1920, and

in a copending applicaiton ofC. F. Vllagner, Serial No. 412,461, filed Sept. 24, .1920;

': Figure, 1 of the accompanying drawings isa cross-sectional view ofa bus-barof usual form combined with a diagram show: ing the ditribution of current therein, Fig. 2. is a cross-sectional view ofa bus vention. t V

Fig. 3 'isa crosssectional View ofa modified form of bus-bar embodying-my invention, and

' Fig. 4 is a cross-sectional view of two of the bus-bars of Fig. 8 and a spacing or supporting member with which they may be associated.

In Fig. 1, a bus-bar 1 of usual form is so bar constructed in accordance with my ini affected by alternating current as, to cause adistribution of current, as indicated by the curve 2. ,With the zero or reference ordinate coincident with one side of the busbar, this figure shows, in generah'that the.

current density of such a conductor is great:

est; at the outer edges 3 thereofand that the density decreases gradually toward thecenter of the conductor. I I I 1 "To obviate this conditiornthe conductor 4 of Fig. 2 is provided. This 3 conductor is shaped, in accordance with the distribution of current as indicated in the current curve 2 of Fig. 1, that is, the thickness of the conductor at any point between is made proportional to the value of the current density indicated at the corresponding point of the current curve 2. Thus each increment of the conductor of j equal area carries an equal current bus-bar having less cross-sectional area than therectangular bar, indicated 1n Fig. 1, may; serve to carry the .same amount of reduction in the quantity of conductive the center and edges of the conductor density. By reason'of this construction, a

current for a given temperature rise. -The the form shownirf Figi 2.

*metal necessaryto form bar having a givenfcapacity, results inconsiderable sav- 'ing of Iirelatively expensive "material. [The conductor maybe provided with regular concave curved surfaces 5 extending throughout thelength thereof or, injFigi 3; may be tapered along 1 straight 'lines 6 from the edges] to -the center thereof. 1 The flatter construction, While providing substantially as good. operating"characteristics,'l

may I have manufacturing advantages "over i Either "form may -be' employed v PQSUJIODHIg member of usual form jsuch as a spacing 'orjsupport ng member 7, to therewith form longitudinal yentilatingspaces'8 .therebetween.

WVhile I have shown and described .pai'e ticularforms ofmy invention, "changes may be, eflected therein i thout 1 departing from f the spirit'and scope thereoi as set forth in 1'the appendedclaims; i I

.Iclaim as my jinventionz I 'i area 'ofthe conductor corresponcls :in dis due to skin effect. v

shape to the natural current densities of the conductor caused by skin effect for effecting with cross-sect on of the conductor."

o 'point proportioned in accordance. with' the skin'eiie'ct whereby-1 substantially} unifror to thecur-rent densitiesdeterinined effect whereby substantially -uniform current: density is 'eliected.

surfaces so disposed that-the cross-sectionaltributionflto the natural currentg -idensitie 4. A substantially flat conductorf-hafiin a cross-sectional: area corresponding in:

uniform current density throughout the [5. A solid conductor having its cross-sec tional areas distributed accordance with 1 the natural current density caused by skin eii'ect, whereby substantially'uniform' dis-' tribution' ofcurrent density isefEectedJ ariiconductor having greaterwidththair thickness and havin'gf-its thickness an current density 'atsuch point determined b current density is efiectedthroughou the area'of the conductor. c H In testimony whereof, I have hereunto subscribed my name 7 this 11th 'da ys 'of r September, "19 20.

conductor having double-concai eij' DOUGLAS ram-NE

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