US3739188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Common wire compensation circuit
Assignee: Johnson Service Co
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Filing: 1971-10-22
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Granted: 1973-06-12
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Expires: 1991-10-22
Abstract
Abstract In an electrical control system having equipment at different locations interconnected by a multi-wire cable including a common wire which links points of reference potential for the equipment, a compensating circuit samples current flowing in the common wire such that whenever a potential difference exists between the reference points a current is generated in a compensating wire which is extended to one of the points of reference potential to minimize the current flow in the common wire thereby equalizing the potentials at the reference points.
Inventors
- 👤 P Froehling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:46
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/08; H04L25/085; G; G05; G05F; G05F1/00; G05F1/10; G05F1/46
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
148 words
In an electrical system including electrical equipment at different locations and a multi-wire cable interconnecting the equipment at the locations, compensating means for minimizing the potential difference between a reference terminal at a first one of the locations and a system ground at a second one of the locations comprising in combination common wire means connected between said reference terminal and said system ground for conducting current whenever a potential difference exists between said reference terminal and said system ground, means at said second location responsive to current conducted by the common wire means to provide a compensating current which is proportional to the amplitude of the current conducted by common wire means, and means for extending the compensating current to said reference terminal to thereby minimize current flow in said common wire means and in turn the potential difference between said reference terminal and said system ground.
Claim 2
Dependent Claim
148 words
In an electrical system including electrical equipment at different locations and a multi-wire cable interconnecting the equipment at the locations, compensating means for minimizing the potential difference between a reference terminal at a first one of the locations and a system ground at a second one of the locations comprising in combination common wire means connected between said reference terminal and said system ground for conducting current whenever a potential difference exists between said reference terminal and said system ground, means at said second location responsive to current conducted by the common wire means to provide a compensating current which is proportional to the amplitude of the current conducted by common wire means, and means for extending the compensating current to said reference terminal to thereby minimize current flow in said common wire means and in turn the potential difference between said reference terminal and said system ground.
Claim 3
Dependent Claim
211 words
In an electrical system including electrical equipment at different locations and a multi-wire cable interconnecting the equipment at the locations, the combination comprising current sensing means connected in series with a common wire of said multi-wire cable between a reference terminal which provides a point of reference potential for electrical equipment at a first one of the locations and a system ground which provides a point of reference potential for electrical equipment at a second one of said locations, said current sensing means providing a voltage proportional to current flowing in the common wire and said current sensing means whenever a potential difference exists between said reference terminal and said system ground, voltage detecting means at said second location having inputs connected to said current sensing means and responsive to the voltage provided by the current sensing means to provide a compensating current at an output of said voltage detecting means, and compensating wire means connected between the output of said voltage detecting means at said second location and said reference terminal at said first location for extending the compensating current to said reference terminal to minimize current flow in said common wire and said current sensing means and thus the potential difference between said reference terminal and said system ground.
Claim 4
Dependent Claim
211 words
In an electrical system including electrical equipment at different locations and a multi-wire cable interconnecting the equipment at the locations, the combination comprising current sensing means connected in series with a common wire of said multi-wire cable between a reference terminal which provides a point of reference potential for electrical equipment at a first one of the locations and a system ground which provides a point of reference potential for electrical equipment at a second one of said locations, said current sensing means providing a voltage proportional to current flowing in the common wire and said current sensing means whenever a potential difference exists between said reference terminal and said system ground, voltage detecting means at said second location having inputs connected to said current sensing means and responsive to the voltage provided by the current sensing means to provide a compensating current at an output of said voltage detecting means, and compensating wire means connected between the output of said voltage detecting means at said second location and said reference terminal at said first location for extending the compensating current to said reference terminal to minimize current flow in said common wire and said current sensing means and thus the potential difference between said reference terminal and said system ground.
Claim 5
Dependent Claim
23 words
A system as set forth in claim 2 wherein said current sensing means includes resistance means connected in series with said common wire.
Claim 6
Dependent Claim
74 words
A system as set forth in claim 3 wherein said voltage detecting means includes amplifier means having inputs connected across said resistance means and an output connected to the output of said voltage detecting means, said amplifier means being responsive to a voltage provided across said resistance means in response to current flow over said common wire and said resistance mEans to provide said compensating current at the output of said voltage detecting means.
Claim 7
Dependent Claim
54 words
A system as set forth in claim 4 wherein said amplifier means includes means for biasing said amplifier means for operation as a high gain amplifier whereby said amplifier means is enabled to provide a relatively high output current in response to a small current flowing in the common wire and said resistance means.
Claim 8
Dependent Claim
61 words
A system as set forth in claim 4 wherein said amplifier means comprises an input stage including an operational amplifier having inputs connected across said resistance means and an output, and an output stage including a power amplifier having an input connected to the output of said operational amplifier and an output connected to the output of said voltage detecting means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |