US3863036A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone subscriber loop ground current detection circuit
Assignee: Nortel Networks Technology Corp
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Filing: 1973-10-11
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Granted: 1975-01-28
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Expires: 1993-10-11
Abstract
Abstract A circuit for indicating a ground current condition at the subscriber end of an operating loop circuit includes a relay having a plurality of coil windings. Two of the coil windings are inserted in series with the tip and ring leads respectively of the loop circuit to detect a current imbalance between the leads. The coil winding of another relay is also inserted in series with the lead terminating at ground in the associated switching office to detect current flow in excess of a minimum amount. Thus when a ground current condition, within certain limits, is present, operation of both relays provides indication of same.
Inventors
- 👤 Crudden John Anthony Mc
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:44
CPC Classifications
H; H04; H04M; H04M17/00; H04M17/02; H04M17/023; H04Q; H04Q3/00; H04Q5/00; H04Q5/24
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
139 words
A circuit for indicating a ground current condition at the subscriber''s end of an operating telephone subscriber''s loop circuit terminated at battery and ground connections in a telephone switching facility, said indication being provided to the telephone switching facility, the cIrcuit comprising: first means for detecting a current flow imbalance of at least a predetermined magnitude between tip and ring leads of the loop circuit, the detection indicating a ground current condition in said loop circuit exceeding a first limit; second means for detecting a current flow of at least a predetermined magnitude in the end of the loop circuit terminated at the ground connection, absence of detection by the second means in the presence of detection by the first means indicating a ground current condition in said loop circuit exceeding a second limit greater than the first limit.
Claim 2
Dependent Claim
139 words
A circuit for indicating a ground current condition at the subscriber''s end of an operating telephone subscriber''s loop circuit terminated at battery and ground connections in a telephone switching facility, said indication being provided to the telephone switching facility, the cIrcuit comprising: first means for detecting a current flow imbalance of at least a predetermined magnitude between tip and ring leads of the loop circuit, the detection indicating a ground current condition in said loop circuit exceeding a first limit; second means for detecting a current flow of at least a predetermined magnitude in the end of the loop circuit terminated at the ground connection, absence of detection by the second means in the presence of detection by the first means indicating a ground current condition in said loop circuit exceeding a second limit greater than the first limit.
Claim 3
Dependent Claim
49 words
A circuit as defined in claim 1 in which said indication is provided via an interface circuit to said telephone switching facility, the interface circuit comprising: enable means, responsive to control from the switching facility, for directing current carried by the loop circuit through said first and second means.
Claim 4
Dependent Claim
160 words
A circuit for indicating a ground current condition at the subscriber''s end of an operating telephone subscriber''s loop circuit, the subscriber''s loop circuit being terminated at battery and ground connections by an originating register circuit in a common control switching facility associated with the loop circuit, the circuit comprising: switch means controllable by the originating register circuit for interrupting tip and ring leads of the loop circuit, a first relay having first and second coils shunting the switch means in the tip and ring leads respectively, the relay being so connected that normal currents in the tip and ring leads cause a field cancelling effect between the first and second coils, a second relay having a coil in series between the second coil and the lead in the loop circuit terminated at said ground connection, first and second relay contacts actuated by said first and second relays respectively, said relay contacts connected to the originating register to provide said indication.
Claim 5
Dependent Claim
160 words
A circuit for indicating a ground current condition at the subscriber''s end of an operating telephone subscriber''s loop circuit, the subscriber''s loop circuit being terminated at battery and ground connections by an originating register circuit in a common control switching facility associated with the loop circuit, the circuit comprising: switch means controllable by the originating register circuit for interrupting tip and ring leads of the loop circuit, a first relay having first and second coils shunting the switch means in the tip and ring leads respectively, the relay being so connected that normal currents in the tip and ring leads cause a field cancelling effect between the first and second coils, a second relay having a coil in series between the second coil and the lead in the loop circuit terminated at said ground connection, first and second relay contacts actuated by said first and second relays respectively, said relay contacts connected to the originating register to provide said indication.
References Cited (Backward Citations)
US3046343A
Cited
US3721768A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |