US3652797A

US3652797A - Safety anchored multiconductor cable for electric arc furnaces

Info

Publication number: US3652797A
Application number: US63405A
Authority: US
Inventors: Daniel J Goodman
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-08-13
Filing date: 1970-08-13
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28
Also published as: DE2140768A1; DE2140768B2; DE2140768C3

Abstract

This multiconductor water-cooled electric arc furnace cable has the majority of its conductors secured within the terminal cup by means of solder. In order to prevent the conductors from dropping out of the terminal cup upon a failure of the water-cooling system causing the solder to melt, two of the conductors are additionally bolted to the inner side of the outer wall of each of the terminal cups. This bolted anchorage prevents the cable from leaving the terminal cup and dropping upon melting of the solder and provides the maximum space for the largest possible central tubular cooling water conduit. It consequently prevents serious damage to the furnace or surroundings and possible injury or deaths of workmen resulting from their coming into contact with the high-voltage high-amperage current thus released, since the conductors still remain connected to the transformer.

Description

United States Patent Goodman 1451 Mar. 28, 1972 [54] SAFETY ANCHORED 3,456,064 7/1969 Toto ..174/1s c MULTICONDUCTOR CABLE F OR' ELECTRIC ARC FURNACES Primary Examiner-E. A. Goldberg Assistant Examiner-A. T. Grimley [72] Inventor: Daniel J. Goodman, 23236 Westbury n B h 1& B b e Ave., St. Clair Shores, Mich. 48080 I 22 Filed: Aug. 13, 1970 [571 ABSTRACT [211 App! 63,405 This multiconductor water-cooled electric arc furnace cable has the ma ority of its conductors secured within the terminal cup by means of solder. ln order to prevent the conductors [52] US. Cl. ..174/l5 C, 174/19, 174/74 R, f dropping out f the terminal cup upon a f il f the 219/130 339/112 water-cooling system causing the solder to melt, two of the [5 l] Int. Cl. ..H0lb 7/34 conductors are additionally bolted to the inner side of the [58] new of Search 1 15 outer wall of each of the terminal cups. This bolted anchorage 174,47; 13/15 339/1 l 12; 219/130 prevents the cable from leaving the terminal cup and dropping upon melting of the solder and provides the maximum space [5 6] References Cited for the largest possible central tubular cooling water conduit. UNITED STATES PATENTS lt consequently prevents serious damage to the furnace or surroundmgs and possible in ury or deaths of workmen resulting Grove 5 C from their coming into ontact the high-voltage higlpam- 3,055,290 1 l/ 1962 Grove 1 74/15 C perage current thus released, since the conductors still remain 3, l TOIO t C connected to the transformer 3,143,593 7/1964 Toto ..l74/15C 3,551,581 12/1970 Goodman 174/15 C 7 Claims, 5 Drawing Figures mtm'enme m2 INVENTOR DANIEL J- GOODMAN ATTORNEYS SAFETY ANCHORED MULTICONDUCTOR CABLE FOR ELECTRIC ARC FURNACES In the drawings, FIG. 1 is a side elevation, partly in central longitudinal section, of one end of a water-cooled electric arc furnace cable,

' showing the safety anchorage construction, according to one form of the invention;

FIG. 2 is a cross section through the cable rearwardly of the terminal, taken along the line 2-2 in FIG. 1;

FIG. 3 is a fragmentary bottom plan view of one of the cable anchoring devices, with the conductor-securing solder omitted, looking in the direction of the line 3-3 in FIG. 1;

FIG. 4 is a fragmentary cross section taken along the line 4-4 in FIG. 1, with the solder present; and

FIG. 5 is'a front end elevation of the cable shown in FIG. 1.

Referring to the drawing in detail, FIG. 1 shows a multiconductor water-cooled electric cable generally designated for electric arc furnaces, the cable 10 being one of a plurality of such cables extending between a conventional transformer (not shown) and an electric arc furnace (not shown). At least three such cables are ordinarily employed, one for each phase of thethree-phase current usually used. Due to the heavy current load demand of such furnaces, however, two to four or more cables 10 may be employed for each phase thus often resulting in a total of six to twelve or more of such cables per furnace. The primary voltage of such a transformer is in the neighborhood of 13,000 volts and the secondary output 230 to 800 volts, with a secondary circuit at 10,000 amperes per phase. Such cables are made in various sizes, one such single cable in a 9,000 MCM size being capable of carrying 21000 amperes and another in an 18,000 MCM size from 45,000 to 50,000 amperes.

In particular, the multiconductor cable 10, of which only the furnace connection end unit 12 is shown, consists of a forward terminal 14 and multiconductor cable unit 15 secured thereto as described below. The forward terminal 14 is constructed of heavy copper having a forward connection portion or blade 16 adapted to be connected to the furnace. A rearward terminal (not shown) of similar construction is connected to the rearward end of the cable unit 15 and connected to the transformer (not shown). The forward portion 16 has flat opposite sides 18 (FIG. 5) by which it is bolted to the connection with the furnace or transformer, as the case may be. It is also provided with multiple-spaced holes 20 extending transversely therethrough. The forward end 22 of the blade 16 is provided with a threaded port 24 leading to the forward end of a cooling water passageway 26, the opposite end of which is provided with a rearward port 28 opening into the rearward portion or cup 30 of the terminal 14.

The terminal cup 30, as its name suggests, is of hollow cylindrical shape with an outer generally cylindrical surface 32 provided with multiple annular frustoconical teeth 34 which engage and penetrate the inner surface 36 of a hose 38 of synthetic rubber such as that known commercially by the name of neoprene. The forward end of the hose 38 is encircled by multiple longitudinally spaced annular hose clamps 40 which tightly grip and indent the hose 38 and in a watertight connection, and force its inner surface 36 into interlocking engagement with the annular teeth 34 on the terminal cup'32.

The tenninal cup 30 is provided adjacent the inner or rearward port 28 with a bore 42 opening into a counterbore 44 with an annular shoulder 46 extending therebetween. Seated in the bore 42 is the forward end of a riser tube 48, preferably of copper, the rearward end of which is seated in and snugly engages the inner cylindrical surface 50 of a flute perforated .core tube 52 of elastic deformable material, such as rubber or synthetic rubber, having multiple spaced perforations 54 therethrough for the flow of cooling water. The fluted outer surface 56 is engaged by the perforated tubular jacket 58 of each jacketed conductor 60, the perforations 62 of which lead to the conductor itself, or so-called rope 64 of fine copper wire, so-called because of its resemblance to a hemp or manila rope.

The perforated forward end of the jacket 58 extends rearwardly for a distance of approximately 2 feet, beyond which its wall becomes imperforate. At this point it is provided with a tubular plastic plug (not shown) held in place by suitable fasteners such as by four brass screws. The rearward terminal (not shown) as stated above, is similar to the forward terminal 14 except that the blade thereof corresponding to the blade 16 is disposed at right angles to the forward blade 16. The construction of the jacketed cable unit 15 and its conductors 60 themselves, together with that of the perforated fluted central tube 52, is conventional and its details rearwardly of the section line 2-2 forms no part of the present invention.

The forward end portion 66, of a plurality, preferably two, of the individual conductors 64, is enclosed in a tubular conductor clamp 68 a short distance rearwardly of its forward end 70 which abuts the annular shoulder 46. The tubular clamp 68 is of rectangular cross section (FIG. 4) and is drilled at 72 to receive the shank of an anchor bolt or stud 74 which also passes through a hole 76 in the flattened portion 78 of the conductor end portion 66 into a threaded hole 80. Threaded onto the inner end of the bolt or stud 74 is a nut 82. The remaining jacketed conductors 60 have their forward ends 70 also abutting the annular shoulder 46 within the terminal cup 30, but are not secured by the anchor bolts 74, nuts 82 and conductor clamps 68.

The non-anchored conductors are secured within the counterbore 44 by a soft solder filling 84 which is poured into the counterbore 42 in a molten condition after the two anchored conductors 64 have been bolted into place. The assembly of the various parts of the conductor cable 10 is believed to be clearly disclosed by the foregoing description of the construction thereof. The forward end portions 56 of the jacketed conductors 60 which are to be anchored, are originally of circular cross section. Their forward end portions 56, however, are passed through short tubes of circular cross section (not shown) and these tubes and the conductor end portions 66 within them are then swaged into rectangular cross section and become the tubular clamps 68 as shown in FIGS. 3 and 4. The swaging action tightly clamps the cable end portion 66 firmly and nonremovably therein, after which the drilling of the clamping tube 68 and the conductor portion therein can be carried OutJAnchoring is then performed in the manner described above, after which the remaining cable ends 66 of the unanchored conductors 64 are then inserted in the counterbore 44. This assembly is then placed in an upright position and molten soft solder is then poured into the cup 30 so as to substantially fill the counterbore 44 and also the interior of the cable hose 38 substantially back to the forward end of the perforated conductor jackets 58.

In operation, the rearward cable terminal (not shown) of each cable 10 is connected to the transformer while the forward blade 16 of the forward terminal 14 is bolted to its connection at the furnace. The port 24 is connected to its corresponding pipe at the furnace while the corresponding rearward terminal port is connected to a source of cooling water. As a result, while the furnace is in operation, the heat generated by the flow of electric current thru each cable 10 and also by the heat of the furnace itself is dissipated by the cooling water flowing through the perforated fluted core 52 and thence around the jacketed conductors 60 by way of the perforations 54 and 62 respectively.

If, for any reason, the flow of water through the cable 10 is interrupted or shut off completely, the temperature rapidly rises within the cable 10 causing the solder filling 84 within the falling against the furnace casing or injuring adjacent workmen, either by their falling weight or, more seriously and perhaps fatally, by the tremendous electric current thus released, especially if water has fallen or is standing upon the floor of the furnace room.

I claim:

1. A safety anchored electrical cable construction for electric arc furnaces, said construction comprising a multiconductor electric cable having a hose with an array of flexible electrical conductors of the same polarity encased therein and with a tubular liquid coolant conducting conduit extending through the center thereof,

an electric arc furnace connection terminal having a furnace connection portion at its forward end and having a cable conductor connection portion extending rearwardly from said furnace connection portion, said cable conductor connection portion having a hollow cylindrical outer wall disposed within said hose in liquid-tight relationship therewith and defining a conductor receiving cavity therewithin,

the forward end portions of said conductors being disposed within said cavity,

a heat-resistant mechanical conductor-clamping device disposed in said cavity in engagement with the forward end portion of one of said conductors and securing the same to the inner side of said outer wall in electrical conducting relationship therewith,

and a fusible electrically conducting filler material also disposed in said cavity and electrically connecting said cable conductor end portions to said cable conductor connection portion.

2. A safety anchored electrical cable construction, according to claim 1, wherein an additional heat-resistant mechanical conductor-clamping device of similar construction and arrangement to said first-mentioned conductor clamping device is disposed in circumferentially spaced relationship thereto and engages the forward end portion of a second electrical conductor and secures the same to said outer wall in electrical conducting relationship therewith.

3. A safety anchored electrical cable construction, according to claim 1, wherein said conductor-clamping device includes a conductor-anchorage member secured to said outer wall and projecting inwardly therefrom into said cavity and wherein means is provided for securing said forward end portion of said one conductor to said conductor-anchorage member.

4. A safety anchored electrical cable construction, according to claim 3, wherein said forward end portion of said one conductor has a hole therethrough, wherein said conductoranchorage member passes through said hole, and wherein a locking element is secured to said member on the opposite side of said conductor end portion from said outer wall.

5. A safety anchored electrical cable construction, according to claim 4, wherein said inwardly projecting member has a threaded portion thereon and wherein said locking element has a correspondingly threaded portion threadedly engaging said threaded portion of said inwardly projecting member.

6. A safety anchored electrical cable construction, according to claim 1, wherein said filler material surrounds said conductor end portions and said conductor-clamping device.

7. A safety anchored electrical cable construction, according to claim 6, wherein said filler material substantially fills the space in said cavity between said intermediate conduit and said outer wall and the interstices of the individual wires of said conductor end portions exclusive of the space therein occupied by the individual wires of said conductor end portions and said clamping device.

Claims

1. A safety anchored electrical cable construction for electric arc furnaces, said construction comprising a multiconductor electric cable having a hose with an array of flexible electrical conductors of the same polarity encased therein and with a tubular liquid coolant conducting conduit extending through the center thereof, an electric arc furnace connection terminal having a furnace connection portion at its forward end and having a cable conductor connection portion extending rearwardly from said furnace connection portion, said cable conductor connection portion having a hollow cylindrical outer wall disposed within said hose in liquidtight relationship therewith and defining a conductor receiving cavity therewithin, the forward end portions of said conductors being disposed within said cavity, a heat-resistant mechanical conductor-clamping device disposed in said cavity in engagement with the forward end portion of one of said conductors and securing the same to the inner side of said outer wall in electrical conducting relationship therewith, and a fusible electrically conducting filler material also disposed in said cavity and electrically connecting said cable conductor end portions to said cable conductor connection portion.

4. A safety anchored electrical cable construction, according to claim 3, wherein said forward end portion of said one conductor has a hole therethrough, wherein said conductor-anchorage member passes through said hole, and wherein a locking element is secured to said member on the opposite side of said conductor end portion from said outer wall.