US2260209A - Electrical connection - Google Patents

Description

Oct. 2, 1941. J. B. BORGADT 2,260,209

ELECTRICAL CONNECTION Filed Sept. 2, 1939 INVENTOR. JOHN B. BORGADT Patented Oct. 21, 1941 UNITED STATES PATENT OFFICE ELECTRICAL CONNECTION John B. Borgadt, East Cleveland, Ohio Application September 2, 1939, Serial No. 293,267

8 Claims.

This invention relates to electrical connections and particularly to an electrical connection between a source of high amperage, low voltage current, such as welding current, to a welding apparatus.

Large conductors such as heretofore employed for conducting high amperage current comprise a comparatively large mass of solid copper or copper laminae, and the connections thereof to the welding, or other, apparatus are effected by passing bolts through the conductor and a connecting member of the apparatus and drawing the conductor tightly against the member. Often a rigid clamping plate is included between the bolt heads and the conductor for distributing the clamping pressure. These prior conductors and connections are not eflicient for several reasons. Due to current behavior, only the surface strata of the conductors are effective to carry current, the material below these strata being relatively ineffective for current conducting purposes. For example, when such a conductor is subjected to alternating current of any amperage at 60 cycles, all of the current is conducted by surface strata of about 0.301 in thickness. Again, eddy current and other currents are induced at the path produced by the clamp and clamping bolts and screws which usually extend through the conductor, these currents comprising, in effect, secondary currents surrounding the main current. The eddy current losses are relatively great.

One of the principal objects of the'present invention is to provide an improved connection and means for effecting the same of such a character that eddy and other currents and the usual A. C. skin effect are eliminated or very greatly reduced, as a result of which much higher eiiiciency in conduction of large currents is obtained.

A more specific object is to provide an effective means for electrically connecting the transformer secondary of a welding apparatus or similar source of high amperage current to the welding apparatus.

Another specific object is to eliminate the disadvantages of the prior type of conductors and connections above described, in the manner and by means disclosed in the following description, wherein reference is made to the drawing, in which:

Fig. 1 is a fragmentary plan view of a conductor and connection embodying the principles of the present invention;

Fig. 2 is a sectional View taken on a plane indicated by the line 2--2 in Fig. 1; and

Fig. 3 is a sectional view taken on a plane indicated by the line 3-3 in Fig. 1.

Referring to the drawing, the conductor, indicated generally at I, is assumed, for purposes of illustration, to be the secondary of a transformer of a resistance welding apparatus. The conductor comprises a plurality of sections, two such sections only being illustrated in the drawing and designated 2 and 3, though any number of sections desired may be utilized, depending upon the electrical characteristics and currents required to be carried.

The apparatus to which the conductor l is to be connected has a current carrying rigid plate 4. The conductor I is clamped to the plate 4 by a suitable rigid clamping plate 5 which is drawn into clamping engagement with the conductor I by means of bolts 6 which may be screw threaded into the plate 4. The bolts 6 are insulated from the clamping plate 5 and the clamping plate 5 from the conductor by suitable insulation '1.

That portion of the plate 4 which is engaged by the conductor I is provided with a plurality of relatively deep grooves 8 which extend lengthwise of the conductors l and from the contact surface of the plate 4 inwardly and which are somewhat greater in length than that surface of the conductor I which engages the plate 4. The grooves 8 are preferably of greater depth than the thickness of that surface portion of the plate 4 which is effective to carry the current, for example, deeper than 0.30'1 inch in the form illustrated.

All sections of the connector I are likewise provided with longitudinal grooves or slots 9 which extend entirely through the connector sections from the top surface which is engaged by the clamp 5 to the bottom surface which is engaged by the plate 4. The slots 9 of the connector are preferably arranged so as to align respectively with the underlying grooves 8 of the plate 4.

The bolts 6 are so spaced that they do not extend through the connector l but extend from the clamping plate 5 directly to the plate 4 at each side of the connector, as illustrated.

The connector l and all sections thereof are built up of a plurality of strips of predetermined thickness, placed face to face, to provide the desired number of laminations. The sections 2 and 3 are likewise of a predetermined total thickness and are spaced apart from each other except where they are between the plates 4 and 5. When the connector is clamped between the plates 4 and 5, the spacing of the sections at that portion is, of course, eliminated but a substantially equivalent effect is produced by the slots 9. Likewise the slots 8 provide a laminated effect in the plate 4.

Before clamping the plates 4 and 5 against the connector l, all of the contact surfaces of the conductor I and plate 4 are silver plated so as to provide the most eiiicient contact and eliminate or reduce oxidation.

By virtue of the laminations and slots and the formation of the connector in sections, the entire conductor is divided up in such a manner that the cross section of no one portion between the slots 9 and no sections 2 or 3 is of greater thickness, or width, as the case may be, than that required for efiicient conduction of current, for example, about 0.602 inch, which is twice the depth to which conductors are effective. Since the usual welding current, in passing through a conductor, penetrates only to a depth'of about 0.301 inch from each face or each surface, all of the metal of the present conductor'is eiective for carrying current. Furthermore, due to the slots and laminations, the eddy currents usually set up in a conductor of large mass which is carrying heavy currents are eliminated or very greatly reduced.

Since the bolts 6 do not pass through the conductor I but outside of the same, the secondary currents around the bolts and ttings are reduced to a minimum. Further, because of the insulating of the bolts 6 from the clamping plate 5, and the plate 5 from the conductor l, the bolts 5, plate 4 and plate 5 do not form a short circuited secondary around the conductor. At the same time the effective contact area of the conductor is greatly increased. Finally, the grooves 8 produce a laminated eiect in the plate to a depth greater than that to which the current penetrates eiiiciently, and also compensate better for any irregularities of the contact surfaces.

Thus I have provided a connection between a large conductor and apparatus used therewith, a means to prevent or greatly reduce the A. C. skin effects in the various ttings, and eddy or secondary currents flowing around the main current, and at the same time have made available a much greater amount of contact area in proportion to the size of the conductor.

I claim:

l. An electrical connection comprising a laminated, transversely solid, metal conductor, slots in the connection portion of said conductor and extending generally in the direction of the thickness of the laminations, and generally longitudinally of the conductor for a distance part way only of the length of the conductor and being approximately coextensive with the connection portion, electrical conducting means having a contact face engaged with a face of the conductor which is parallel to the laminations, and clamping means for drawing said conducting means and conductor rmly together.

2. An electrical connection comprising a plurality of laminated metal conductor sections, the laminated sections being spaced from each other laterally of the conductor, each of said sections having a connection portion, elongated slots -in each of lsaid connection `portionsand extending generally in the direction of the lthickness of the laminations, and longitudinally of the associated connection portion, electrical conducting means having a contact face engaged with a face of the conductor which is parallel to the laminations, and clamping means fordrawing said ccnducting means and conductor iirmly together.

3. An electrical connection comprising a transversely solid, laminated metal conductor, the connecting portion thereof having elongated slots therein which extend generally in a direction normal to the laminations and longitudinally of the connecting portion, transversely continuous electrical conducting means extending the entire width of said connecting portion and having a contact -face engaged with a face of the conductor which is parallel to the laminations, and having relatively deep grooves opening in the contact face thereof and substantially aligned with said slots and extending part way only of the thickness of the conducting means, and clamping means for drawing said conducting means and conductor firmly together.

4. An electrical connection comprising a plurality of laminated, transversely solid, metal conductors spaced lapart transversely from each other, each conductor having slots in a portion to be connected, said slots extending entirely through said portion in a direction normal to the laminations and extending longitudinally thereof, electrical conducting means having a contact face in contact with a-face of said portion which is parallel to the laminations, a clamping member engaging the opposite face of the said portion, bolts operatively engaging said means and member for drawing said means and portion rmly into contact relation, and said bolts beingelectrically insulated from said clamping member.

5. An electrical connection comprising a transversely solid, metal conductor having a portion to be connected, a transversely continuous electrical conducting means having a contact face in contact with a face of said portion, clamping means for drawing said conducting means and portion rmly into Contact relation, and said conducting means having relatively narrow, deep grooves in its contact face extending generally lengthwise of the conductor and separating the contact face into contact face portions which are materially wider than the grooves.

6. An electrical connection comprising a laminated metal conductor having slots in a portion to be connected and extending part way only of the length of the conductor, said slots extending entirely through said portion in a direction normal to the laminations and extending longitudinally thereof, electrical conducting means having a contact face in contact with a face of said lportion which is parallel to the laminations, a clamping member engaging the opposite face o1' the said portion, bolts operatively engaging said means and member outside of the limits of the conductor and portion for drawing said means and portion rmly into contact relation, and said bolts being electrically insulated from said clamping member.

7. An electrical connection comprising a ylaminated metal conductor comprising a plurality of laminated sections spaced from each other transversely in a direction parallel to the plane of the laminations, each of said sections having a connection portion, slots in each of said portions and extending yentirely therethrough in a direction normal -to the laminations and extending longitudinally thereof, a transversely continuous conducting member having a Contact face engaged with a face of said portions which is parallel to the laminations, relatively narrow deep grooves in the said member and opening in the contact face thereof and spaced apart laterally with respect to each other a distance equal to the spacing of the slots of the connector sections, and being aligned with the said slots, a clamping member engaging the face of the conductor opposite from the second conductor, means outside of the lateral limits of each section for drawing said members firmly into clamping relation to the said portion of the conductor, said means being electrically insulated from one of said members.

8. An electrical connection comprising a transversely continuous conductor, a transversely oontinuous plate having a face in Contact with a.

face of the conductor and extending transversely thereof, means for clamping the conductor rmly against the face of said plate, and grooves in said plate extending lengthwise of the conductor along the contact area thereof and inwardly from the contact face part way only of the thickness of the plate for reducing the current losses in said plate and grooves extending longitudinally of the conductor part way only of its length and entirely through the conductor, said grooves being in the connecting portion of the conductor, and the mutually contacting faces of the conductor and plate being silver plated.

JOHN B. BORGADT.

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