US3898707A - Low balanced reactance delta closure for electric arc furnace transformers - Google Patents

Low balanced reactance delta closure for electric arc furnace transformers Download PDF

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Publication number
US3898707A
US3898707A US491080A US49108074A US3898707A US 3898707 A US3898707 A US 3898707A US 491080 A US491080 A US 491080A US 49108074 A US49108074 A US 49108074A US 3898707 A US3898707 A US 3898707A
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US
United States
Prior art keywords
phase
tubular
coolant
vault
conductor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US491080A
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English (en)
Inventor
James J Trageser
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
United States Steel Corp
Original Assignee
United States Steel Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United States Steel Corp filed Critical United States Steel Corp
Priority to US491080A priority Critical patent/US3898707A/en
Priority to IN2768/CAL/74A priority patent/IN140062B/en
Priority to AU76613/74A priority patent/AU489566B2/en
Priority to GB5492674A priority patent/GB1459290A/en
Priority to NL7416876A priority patent/NL7416876A/xx
Priority to BR169/75A priority patent/BR7500169A/pt
Priority to ES433734A priority patent/ES433734A1/es
Priority to IT67058/75A priority patent/IT1027279B/it
Priority to JP565575A priority patent/JPS5737116B2/ja
Priority to AT20575A priority patent/AT349770B/de
Priority to DE19752501106 priority patent/DE2501106A1/de
Priority to FR7501012A priority patent/FR2258075B1/fr
Application granted granted Critical
Publication of US3898707A publication Critical patent/US3898707A/en
Assigned to USX CORPORATION, A CORP. OF DE reassignment USX CORPORATION, A CORP. OF DE MERGER (SEE DOCUMENT FOR DETAILS). Assignors: UNITED STATES STEEL CORPORATION (MERGED INTO)
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G5/00—Installations of bus-bars
    • H02G5/10—Cooling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/11—Arrangements for conducting current to the electrode terminals

Definitions

  • a typical arrangement includes a high voltage power supply connected to a transformer to provide a high current output at a relatively low voltage.
  • the transformer output is delta connected to cable terminal bars, through a group of flexible cables to one end of a group of bus tubes mounted on a movable mast supporting electrode holders over the top of the furnace.
  • the other end of the bus tubes are connected to the furnace electrodes. Because of high currents involved, the flexible tubes and the bus tubes mounted on the mast are water cooled.
  • the flexible cable connection is required to permit movement of the furnace top and tilting of the furnace.
  • the transformer is usually enclosed in a pressurized protective vault as near the furnace as is convenient and includes a cooling system for the transformer.
  • the power transformer has a plurality of secondary coil terminal blades projecting from the top face of the transformer. Secondary riser extension bars are bolted to the blades and to a series of closure bars, one for each transformer secondary coil terminal, which are in turn bolted to the three cable terminal bars.
  • the cable terminal bars project through the wall of the vault with the closure bars inside the vault and the cable connections outside the vault.
  • In large capacity transformers there may be as many as seventy-two or ninety-six air cooled closure bars converging diagonally from the risers to the cable terminal bars.
  • Each closure bar may be in two parallel sections with spacers between the sections. This type of closure requires a complex series of support timbers and comb spacers for the closure bars.
  • the transformer vault is usually sealed and provided with a positive air pressure to prevent entrance of dirt which can accumulate on the closure bars and supporting structure and cause flashovers.
  • the flow of filtered air also serves to cool the transformer and the structure in the vault, and if desired, the air may be cooled before entry into the vault.
  • Impedance unbalance is caused by different conductor length and unbalanced spacial relationships between the three conductors.
  • the impedance unbalance becomes even more important with the trend towards higher currents, while a typical I50 ton furnace operated at 40,000 amperes a few years ago, 150 ton furnaces now operate at about 80,000 amperes.
  • Such high currents create considerable heating problems and conductor support problems as heated copper bars tend to char supporting timbers.
  • I provide a delta closure for a transformer having relatively short riser extension bars bolted to riser extension bar brackets.
  • the brackets are welded to water cooled tubular coil collectors which are in turn welded to water cooled tubular phase conductors projecting through the transformer vault wall and ending with the flexible cable terminals.
  • the phase collectors and the flexible cable terminal heads are supported by hanger rods, and the spacing of the water cooled tubular phase conductors permits maximum reactance balancing to compensate for imbalance in the flexible cables and electrode bus bars.
  • Water cooling is connected to the flexible cableelectrode bus bar cooling system with no connections inside the vault.
  • Another object is to provide such a closure that is liq uid cooled.
  • a still further object is to provide such a closure which is easily supported by hanger rods yet another object is to provide such a closure having no coolant connections inside the transformer vault.
  • FIG. 3 is a schematic side elevation of the delta closure assembly
  • FIG. 4 is a schematic front elevation of the delta closure assembly
  • FIG. 8 is a sectional detail of the connection between the tubular coil collector and the tubular phase conductor of phase C.
  • FIG. 9 is a cross sectional view along line IX--IX of FIG. 5 showing the coolant connections of phase C.
  • FIG. 11 is a cross sectional view along line XIXI of FIG. 5 showing the coolant connections and stiffeners of phase B.
  • FIG. 12 is a cross sectional view along line XII-XII of FIG. 5 showing stiffener details.
  • a typical three phase electric furnace installation includes a large cylindrical furnace housing 2, upon which rests a movable roof 4. Electrodes 6 project downward through the roof 4 and are supported by electrode holders mounted on a mast assembly 8 which also supports bus tubes 10. Bus tubes 10 are usually water cooled and are connected at one end to the holders for electrodes 6 and at the other end to mast cable terminal heads 12. Flexible water cooled cables 14 are connected from the mast cable terminal heads 12 to the transformer cable terminal heads 16. Terminal heads 16 are connected through the closure system of my invention to a power transformer 18. Transformer 18 is enclosed in a vault 20, only a pan of which is shown, and is connected to a source of high voltage three phase alternating current 22. A cooling system 24, partially shown in FIG. 2, is provided to cool vault 20. Transformer 18 provides a high current low voltage output and is usually provided with a cooling system, not shown. The parts thus far described, with the exception of the closure system, are conventional.
  • reference numeral 26 indicates a plurality of transformer secondary coil terminal blades rising from the top of the transformer 18.
  • the terminal blades 26 as shown in FIG. 4 are in three groups, with the ends of each secondary coil connected to a pair of adjacent blades.
  • Bolts 28 affix a pair of terminal riser bars 30 to each terminal blade 26.
  • a riser extension bar 32 is affixed to the top of each pair of terminal riser bars 30 by bolts 34.
  • the designation of the riser extension bars is shown in FIG. 3 as 32A for phase A, 328 for phase B and 32C for phase C.
  • Each riser extension bar is welded to a tubular coil or phase collector 36 which may be, for example, a square hard drawn high conductivity copper tube 8 inches square with /2 inch wall thickness.
  • Each phase collector has three or more vertical support hanger lugs 38, as best shown in FIG. 5.
  • the hanger lugs are connected by hanger rod assemblies 40 which include turnbuckles, eyebolts, rods, clevis and an insulator 42, to roof beams 44 of transformer vault 20. For clarity, only a portion of the support rods 40 and roof beams 44 are shown.
  • the ends of each tubular collector 36 are closed by end caps 46.
  • a pair of hollow riser tubes 48A is welded to phase collector 36A.
  • Riser tubes 48A may be, for example, hard drawn high conductivity copper tubes six inches square with /2 inch wall thickness.
  • a pair of hollow riser tubes, 488, similar to riser tubes 48A, is welded to phase collector 363.
  • a tubular phase conductor is made of two tubes 50B, is welded to the ends of riser tubes 48B and projects through vault wall 52.
  • Supporting and insulating timbers 54 surround tubes 50B for a snug fit through an opening in vault wall 52.
  • Another tubular phase conductor is made of two tubes 50A, is welded to the end of riser tubes 48A and projects through vault wall 52 in the same manner as tubes 50B.
  • a third phase conductor is made of two tubes 50C, is welded to phase collector 36C and likewise projects through vault wall 52.
  • Tubes 50A, 50B and 50C may each be, for example, hard drawn high conductivity copper tubes siz inches square with /2 inch wall thickness.
  • a pair of terminal heads 56 is welded on the end of each phase conductor.
  • FIG. 3 shows only a portion of the hanger rod assembly 58B and FIG. 4 Shows only a portion of one of the hanger rod assemblies 588.
  • Cables 14 are equipped with lugs which are bolted to terminal heads 56.
  • the ends of tubes 50 to which terminal heads 56 are attached have end caps 60 welded in place.
  • phase collector 36A has a diagonal coolant separator 62A inserted inside it extending almost the entire length of collector 36A as shown in FIG. 5.
  • Separator 62A may be /2 inch thick hard drawn high conductivity copper.
  • a hole 64 passes coolant from the upper right half of collector 36A into the outlet riser tube 48A, and matching holes 66 in collector 36A and inlet riser tube 48A passes coolant from the inlet riser tube 48A to the lower left half of collector 36A.
  • a cap 68 welded in place, covers the end of inlet riser tube 48A and a spacer 70 separates riser tubes 48A between the connection to collector 36A and the connection to the phase conductor 50A.
  • a coolant inlet 72A is connected to the lower inlet tube 50A and a coolant outlet 74A is connected to the upper tube 50A.
  • An air bleeder plug 76A is provided in the lower outlet tube 50A. Drain plugs 78A are provided at each end on the bottom side of phase collector 36A as shown in FIG. 5.
  • FIGS. I1 and 12 show a preferred stiffener in one of the tubes, other stiffeners may be used or stiffeners may be used in both tubes.
  • the stiffener consists of a stainless steel tube 94, sealed at both ends.
  • Four corner spacers, 96 are welded to tube 94 so that the tube and spacer assembly fits snugly inside lower inlet tube 50B.
  • Tube 94 extends from nearly one end of tube 508 to the other end as shown in FIG. 5.
  • the spacers 96 may conveniently extend about the same distance.
  • This configuration of the stiffener provides four sub-passageways for coolant through the stiffened tube 50B.
  • a baffle 98 is placed in the lower quadrant passage so that the entering coolant will be forced into other passageways.
  • reference numeral 100 indicates a coolantsupply header which may be conveniently mounted on vault wall 52. Header 100 is connected to a source of coolant, not shown. The source may be a pumpsupplying cool water or other coolant under pressure from a cooling tower, coolant tank, cooling pond or whatever may be convenient for the particular furnace installation.
  • a flexible rubber hose 102 connects the supply header to coolant inlet 72C. Coolant flows through inlet tube 50C, through hole 82, FIG. 8, into the lower left half of collector 36C.
  • the reactance is considerably lower than the reactance in the conventional system using diagonally converging closure bars.
  • the triangular spatial relation of the phase conductor tubes as they project through the transformer vault wall also contribute to a lower reactance.
  • the conductors are terminated outside the vault wall to provide a triangular spatial relation to the flexible cables.
  • phase conductors for each phase, said conductors being arranged generally parallel to each other and in a triangular spatial relation, each of said phase conductors having means connecting one end thereof to one of said phase collectors and;
  • a closure according to claim 2 which includes a closed transformer vault, insulating means in a wall of said vault surrounding said phase conductors where they pass through the wall in the triangular spatial relation, means inside said vault and attached to said vault for supporting the phase collectors and means outside said vault and attached to said vault for supporting th flexible cable terminal heads.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Furnace Details (AREA)
  • Discharge Heating (AREA)
  • Ac-Ac Conversion (AREA)
US491080A 1974-01-14 1974-07-23 Low balanced reactance delta closure for electric arc furnace transformers Expired - Lifetime US3898707A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US491080A US3898707A (en) 1974-01-14 1974-07-23 Low balanced reactance delta closure for electric arc furnace transformers
IN2768/CAL/74A IN140062B (de) 1974-01-14 1974-12-17
AU76613/74A AU489566B2 (en) 1974-12-18 Low balanced reactance delta connection for electric arc furnace transformers
GB5492674A GB1459290A (en) 1974-01-14 1974-12-19 Low balanced reactance delta closure for electric arc furnace transformers
NL7416876A NL7416876A (nl) 1974-01-14 1974-12-24 Elektrische vlamboogoven.
BR169/75A BR7500169A (pt) 1974-01-14 1975-01-10 Fechamento em triangulo de baixa reatancia equilibrada ligando um transformador de forca a cabos flexiveis em um forno de arco voltaico trifasico
ES433734A ES433734A1 (es) 1974-01-14 1975-01-11 Perfeccionamientos introducidos en un cierre en triangulo de baja reactancia equilibrada en o para un horno de arco e-lectrico trifasico.
IT67058/75A IT1027279B (it) 1974-01-14 1975-01-13 Dispositivo di chiusura a triangolo a bassa reattanza bilanciata,per trasofrmatori di forni elttrici ad arco
JP565575A JPS5737116B2 (de) 1974-01-14 1975-01-13
AT20575A AT349770B (de) 1974-01-14 1975-01-13 Dreieckschaltungsanordnung mit geringer, ausgeglichener reaktanz zum verbinden eines ofentransformators mit einem drehstromlicht- bogenofen
DE19752501106 DE2501106A1 (de) 1974-01-14 1975-01-13 Dreieckschaltungsanordnung fuer einen elektrischen dreiphasen-lichtbogenofen
FR7501012A FR2258075B1 (de) 1974-01-14 1975-01-14

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43291874A 1974-01-14 1974-01-14
US491080A US3898707A (en) 1974-01-14 1974-07-23 Low balanced reactance delta closure for electric arc furnace transformers

Publications (1)

Publication Number Publication Date
US3898707A true US3898707A (en) 1975-08-12

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ID=27029676

Family Applications (1)

Application Number Title Priority Date Filing Date
US491080A Expired - Lifetime US3898707A (en) 1974-01-14 1974-07-23 Low balanced reactance delta closure for electric arc furnace transformers

Country Status (11)

Country Link
US (1) US3898707A (de)
JP (1) JPS5737116B2 (de)
AT (1) AT349770B (de)
BR (1) BR7500169A (de)
DE (1) DE2501106A1 (de)
ES (1) ES433734A1 (de)
FR (1) FR2258075B1 (de)
GB (1) GB1459290A (de)
IN (1) IN140062B (de)
IT (1) IT1027279B (de)
NL (1) NL7416876A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4018975A (en) * 1975-03-21 1977-04-19 Pennsylvania Engineering Corporation Suspension means for electric furnace transformer secondary buses
US4153812A (en) * 1977-10-21 1979-05-08 Lectromelt Corporation Bus bar assembly
US5715273A (en) * 1995-04-14 1998-02-03 Danieli & C. Officine Meccaniche Spa Secondary circuit with variable impedance for electric arc furnaces
US20110056719A1 (en) * 2006-02-10 2011-03-10 Areva Nc Electricity transmission device at high current and high frequency

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3106827A1 (de) * 1981-02-24 1982-09-09 Fried. Krupp Gmbh, 4300 Essen "elektroden- und leiteranordnung eines dreiphasigen lichtbogenofens"
DE3808683C1 (de) * 1988-03-11 1989-09-07 Mannesmann Ag, 4000 Duesseldorf, De
DE3814261A1 (de) * 1988-04-27 1989-11-09 Fuchs Systemtechnik Gmbh Lichtbogenofen mit zuschaltbarer zusatz-reaktanz

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1386828A (en) * 1920-09-16 1921-08-09 Gen Electric Windings for electrical apparatus
US3366725A (en) * 1964-12-21 1968-01-30 Watteredge Co Balancing a three-phase power transmission system for an electric arc furnace

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1386828A (en) * 1920-09-16 1921-08-09 Gen Electric Windings for electrical apparatus
US3366725A (en) * 1964-12-21 1968-01-30 Watteredge Co Balancing a three-phase power transmission system for an electric arc furnace

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4018975A (en) * 1975-03-21 1977-04-19 Pennsylvania Engineering Corporation Suspension means for electric furnace transformer secondary buses
US4153812A (en) * 1977-10-21 1979-05-08 Lectromelt Corporation Bus bar assembly
US5715273A (en) * 1995-04-14 1998-02-03 Danieli & C. Officine Meccaniche Spa Secondary circuit with variable impedance for electric arc furnaces
AU695299B2 (en) * 1995-04-14 1998-08-13 Danieli & C. Officine Meccaniche S.P.A. Secondary circuit with variable impedance for electric arc furnaces
US20110056719A1 (en) * 2006-02-10 2011-03-10 Areva Nc Electricity transmission device at high current and high frequency
US8119908B2 (en) 2006-02-10 2012-02-21 Areva Nc Electricity transmission device at high current and high frequency

Also Published As

Publication number Publication date
JPS50102944A (de) 1975-08-14
DE2501106A1 (de) 1975-07-17
AT349770B (de) 1979-04-25
AU7661374A (en) 1976-06-24
BR7500169A (pt) 1975-11-04
ATA20575A (de) 1978-09-15
NL7416876A (nl) 1975-07-16
IT1027279B (it) 1978-11-20
FR2258075A1 (de) 1975-08-08
FR2258075B1 (de) 1982-03-05
ES433734A1 (es) 1976-12-01
JPS5737116B2 (de) 1982-08-07
IN140062B (de) 1976-09-04
GB1459290A (en) 1976-12-22

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Legal Events

Date Code Title Description
AS Assignment

Owner name: USX CORPORATION, A CORP. OF DE, STATELESS

Free format text: MERGER;ASSIGNOR:UNITED STATES STEEL CORPORATION (MERGED INTO);REEL/FRAME:005060/0960

Effective date: 19880112