US3668472A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ground detection circuit for a d.c. distribution network
Assignee: Gilbert Associates Inc
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Filing: 1971-05-17
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Granted: 1972-06-06
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Expires: 1991-05-17
Abstract
Abstract The invention relates to a ground detection circuit for an ungrounded D.C. distribution network. The sensitivity to ground is uniquely independent of polarity of the D.C. bus on which the ground occurs. The occurrence of multiple grounds will cause the ground detection circuit to operate as if all such ground resistances were in parallel with each other. The principle of detection is based on the fact that the algebraic sum of currents flowing through a resistance, having one end connected to ground and the other end being alternately connected to the plus and then to the minus bus of the center tap battery source, is inversely proportional to the ''''total resistance'''' to ground of the network, where ''''total resistance'''' is the equivalent of placing all resistances to ground in parallel.
Inventors
- 👤 William B Shields
- 👤 Victor H Willems
- 👤 William F Sailer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:34
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/16
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
75 words
An unground D.C. distribution network including a positive bus, a negative bus and a source of direct current connected across said busses, tap means for said source, a resistance network connected between said busses and ground including a resistor, and switching means for connecting one end of said resistor alternately to said positive and negative busses, and ground detector means responsive to the sum of the currents flowing through said resistor during said alternate connections.
Claim 2
Dependent Claim
75 words
An unground D.C. distribution network including a positive bus, a negative bus and a source of direct current connected across said busses, tap means for said source, a resistance network connected between said busses and ground including a resistor, and switching means for connecting one end of said resistor alternately to said positive and negative busses, and ground detector means responsive to the sum of the currents flowing through said resistor during said alternate connections.
Claim 3
Dependent Claim
29 words
A network as recited in claim 1 wherein said resistance network includes a time base and wherein said switching means includes a flip-flop circuit triggered by said time base.
Claim 4
Dependent Claim
21 words
A network as recited in claim 2 wherein said flip-flop circuit includes silicon controlled rectifier means for operating said switching means.
Claim 5
Dependent Claim
51 words
A network as recited in claim 1 wherein said ground detector includes a diode and a capacitor which is charged to a voltage proportional to the current flowing away from ground through said resistor, said diode preventing the capacitor from discharging its accumulated charge when switching to the opposite polarity bus.
Claim 6
Dependent Claim
30 words
A network as recited in claim 4 but with an opposite polarity diode, its capacitor being charged to a voltage proportional to the current flowing towards ground through said resistor.
Claim 7
Dependent Claim
21 words
A network as recited in claim 4 wherein said ground detector means also includes a unijunction transistor which controls a thyristor.
Claim 8
Dependent Claim
54 words
A network as recited in claim 6 together with a control relay so that upon attainment of a predetermiNed total charge across said capacitors, representative of a predetermined value of ground resistance, said control relay will be operated by the turning on of the thyristor by discharge of said capacitors through said unijunction transistor.
Claim 9
Independent Claim
76 words
The method of detecting a ground in an underground D.C. distribution network including a positive bus, a negative bus, a source of direct current connected across said busses having tap means and a resistance network connected between said busses and said ground, including a resistor; which method comprises connecting one end of said resistor alternately to said positive and negative busses and detecting the algebraic sum of currents flowing through said resistor during said alternate connections.
Claim 10
Independent Claim
76 words
The method of detecting a ground in an underground D.C. distribution network including a positive bus, a negative bus, a source of direct current connected across said busses having tap means and a resistance network connected between said busses and said ground, including a resistor; which method comprises connecting one end of said resistor alternately to said positive and negative busses and detecting the algebraic sum of currents flowing through said resistor during said alternate connections.
References Cited (Backward Citations)
US3066284A
Cited
US3573552A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |