US3792350A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detection of metalshield faults in buried cable
Assignee: AT&T Inc
•
Filing: 1972-03-15
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Granted: 1974-02-12
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Expires: 1992-03-15
Abstract
Abstract The electric field configuration generated by exciting a cable shield with an ac signal is detected by an earth prod in directions that are respectively perpendicular and parallel to the cable axis with respect to a ground plane. The field components in the vicinity of an open in the shield exhibit characteristic changes that are extensive and readily detectable with conventional amplifying equipment. Cable locating methodology is also disclosed.
Inventors
- 👤 F Bossler
- 👤 W Kent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:30
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/50; G01R31/58
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
201 words
A method for locating electrical opens in the metallic shield of a buried communications cable comprising the steps of: at one side of said electrical open, connecting an ac signal generator between said shield and an earth ground; grounding said shield on the other side of said open; disconnecting said shield from any other ground connections; energizing said generator with a signal in the range 200 Hz - 10 kHz thereby creating an electric field by capacitive coupling between said shield and the earth; using a probe comprising two spaced-apart earth prods connected in series to amplifier means having an input impedance at least high enough to exceed the soil resistance between said prods, oriented in a position substantially perpendicular to the cable axis as viewed in the ground plane, probing the earth''s surface along the cable run to detect where the field strength rate of decrease is greatest, the latter denoting the localized region where said open is located; and probing in said region with said probe oriented in a position substantially parallel to the cable axis to detect the point where the field strength exhibits an abrupt peak, the latter denoting the substantially exact location of said shield open.
Claim 2
Independent Claim
201 words
A method for locating electrical opens in the metallic shield of a buried communications cable comprising the steps of: at one side of said electrical open, connecting an ac signal generator between said shield and an earth ground; grounding said shield on the other side of said open; disconnecting said shield from any other ground connections; energizing said generator with a signal in the range 200 Hz - 10 kHz thereby creating an electric field by capacitive coupling between said shield and the earth; using a probe comprising two spaced-apart earth prods connected in series to amplifier means having an input impedance at least high enough to exceed the soil resistance between said prods, oriented in a position substantially perpendicular to the cable axis as viewed in the ground plane, probing the earth''s surface along the cable run to detect where the field strength rate of decrease is greatest, the latter denoting the localized region where said open is located; and probing in said region with said probe oriented in a position substantially parallel to the cable axis to detect the point where the field strength exhibits an abrupt peak, the latter denoting the substantially exact location of said shield open.
Claim 3
Dependent Claim
21 words
The method of claim 1 wherein the earth ground for said generator is placed remotely from said generator and said shield.
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein said generator is operated at a voltage level not in excess of 18 volts.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |