US4586188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for converting a three-phase arc furnace to d.c. operation
Assignee: BBC BROWN BOVERI & COMPANY Ltd
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Filing: 1984-03-01
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Granted: 1986-04-29
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Expires: 2004-03-01
Abstract
Abstract An apparatus for converting an arc furnace installation from three-phase operation to d.c. operation wherein in order to ensure optimum d.c. operation after converting the three-phase arc furnace installation to d.c. operation, while retaining the three-phase furnace transformer and the high-voltage switchgear, there is connected an adaptation member (2, 7) for adjusting the arc voltage and/or for increasing the inductive reactance, in addition to the actual rectifier arrangement. This adaptation member is formed of a transformer, preferably an autotransformer, and/or a choke circuit.
Inventors
- 👤 Karl Buhler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:16
CPC Classifications
H; H05; H05B; H05B7/00; H05B7/02; H05B7/144; Y; Y02; Y02P; Y02P10/00; Y02P10/25
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
79 words
An apparatus for converting an arc furnace installation from three-phase operation to d.c. operation, the arc furnace installation having a high-voltage transformer, a controllable three-phase furnace transformer, a furnace casing and at least two electrodes, comprising an autotransformer having a transformation ratio of a primary voltage to a secondary voltage in a range from 1.2 to 2.5 for increasing the inductive reactance, and a rectifier circuit connected in between a secondary side of the three-phase transformer and the electrodes.
Claim 2
Independent Claim
79 words
An apparatus for converting an arc furnace installation from three-phase operation to d.c. operation, the arc furnace installation having a high-voltage transformer, a controllable three-phase furnace transformer, a furnace casing and at least two electrodes, comprising an autotransformer having a transformation ratio of a primary voltage to a secondary voltage in a range from 1.2 to 2.5 for increasing the inductive reactance, and a rectifier circuit connected in between a secondary side of the three-phase transformer and the electrodes.
Claim 3
Dependent Claim
24 words
An apparatus according to claim 1, comprising: a choke circuit connected in series between a secondary side of the autotransformer and the rectifier circuit.
Claim 4
Dependent Claim
25 words
An apparatus according to claim 1, wherein a ratio of a short-circuit current to an operating current is in a range between 1.2 and 3.5.
Claim 5
Dependent Claim
14 words
An apparatus according to claim 1, wherein said rectifier circuit comprises: a controllable rectifier.
Claim 6
Dependent Claim
23 words
An apparatus according to claim 1, wherein at least one of said electrodes is arranged as a bottom electrode in the furnace casing.
Claim 7
Independent Claim
78 words
An apparatus for converting an arc furnace installation from three-phase operation to d.c. operation, the arc furnace installation having a high-voltage transformer, a controllable three-phase furnace transformer, a furnace casing and at least two electrodes, comprising: an autotransformer having a transformation ratio of a primary voltage to a secondary voltage in a range 1.2 to 2.5 for adjusting the secondary voltage and a rectifier circuit connected in between a secondary side of the three-phase transformer and the electrodes.
Claim 8
Independent Claim
78 words
An apparatus for converting an arc furnace installation from three-phase operation to d.c. operation, the arc furnace installation having a high-voltage transformer, a controllable three-phase furnace transformer, a furnace casing and at least two electrodes, comprising: an autotransformer having a transformation ratio of a primary voltage to a secondary voltage in a range 1.2 to 2.5 for adjusting the secondary voltage and a rectifier circuit connected in between a secondary side of the three-phase transformer and the electrodes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-04-28 | 1989-10-28 | 1990-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-28 | 1993-10-28 | 1994-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-28 | 1997-10-28 | 1998-04-29 | $7700.00 | Window Closed / Lapsed |