Patent US3753088A successfully refreshed from Google Patents.
US3753088A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for testing the adequacy of electrical circuit such as the ground circuit of an extension cord
Assignee: MULTI AMP CORP
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Filing: 1971-07-19
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Granted: 1973-08-14
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Expires: 1991-07-19
Abstract
Abstract Device for testing the adequacy of the ground and power circuits of electric tools, extension cord and the like by performing an automated series of individual tests in sequence. The major tests are to determine: open ground circuit, faulty ground circuit, short circuit and poor insulation. If no faults are found by these tests, the circuit under test is next connected to line potential to determine if it operates properly. During this phase of testing, the potentials and currents associated with the previous tests are discontinued to avoid power drain and heating. A saturating current transformer protects an essential relay from damage from excessive current. A long extension cord having a proper ground resistance (in the order of the resistance exhibited by a tool having a faulty ground cord) may be tested by modifying the test currents so that an erroneous faulty ground indication is not given.
Inventors
- 👤 D Ettelman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:47
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/16; G01R27/18
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
178 words
A device for testing the adequacy of electric circuits of both a first and a second type, in which an electrical characteristic of a circuit of the first type is adequate if within a first range and the electrical characteristic of a circuit of the second type is adequate if within a second range different from said first range, including means for generating testing electrical signals, means for applying said signals to a circuit under test which is one of said two type, and means for detecting the electrical response of the circuit under test and providing an indication of said resonse which is representative of said electrical characteristic of the circuit under test, wherein the improvement comprises: means coupled to said detecting means and active only when a circuit of one of said types is under test for varying the indication provided by the detecting means to produce substantially identical indications when a first type circuit under test has its characteristic within said first range and a second type circuit has its characteristic within said second range.
Claim 2
Independent Claim
178 words
A device for testing the adequacy of electric circuits of both a first and a second type, in which an electrical characteristic of a circuit of the first type is adequate if within a first range and the electrical characteristic of a circuit of the second type is adequate if within a second range different from said first range, including means for generating testing electrical signals, means for applying said signals to a circuit under test which is one of said two type, and means for detecting the electrical response of the circuit under test and providing an indication of said resonse which is representative of said electrical characteristic of the circuit under test, wherein the improvement comprises: means coupled to said detecting means and active only when a circuit of one of said types is under test for varying the indication provided by the detecting means to produce substantially identical indications when a first type circuit under test has its characteristic within said first range and a second type circuit has its characteristic within said second range.
Claim 3
Independent Claim
163 words
A device for testing the adequacy of electrical circuiJs of more than one type of electrical device, such as the ground circuit of an extension cord and the ground circuit of an electrical tool, including means for generating testing electrical signals coupled to a parallel combination having as one leg an electrical circuit under test and as the other leg a first winding, the field from said winding controlling the energization of an indicating device, wherein the improvement comprises: a second winding active only when an electrical circuit of one particular type is under test and responsive to the current flowing in a portion of the combination for providing a field coacting with the field from the first winding to vary the energization of said indicating device to cause substantially identical output indications by said indicating device for different types of circuits under test notwithstanding the fact that the currents through said first winding vary for said different types of circuits under test.
Claim 4
Independent Claim
163 words
A device for testing the adequacy of electrical circuiJs of more than one type of electrical device, such as the ground circuit of an extension cord and the ground circuit of an electrical tool, including means for generating testing electrical signals coupled to a parallel combination having as one leg an electrical circuit under test and as the other leg a first winding, the field from said winding controlling the energization of an indicating device, wherein the improvement comprises: a second winding active only when an electrical circuit of one particular type is under test and responsive to the current flowing in a portion of the combination for providing a field coacting with the field from the first winding to vary the energization of said indicating device to cause substantially identical output indications by said indicating device for different types of circuits under test notwithstanding the fact that the currents through said first winding vary for said different types of circuits under test.
Claim 5
Dependent Claim
31 words
A device as in claim 2, in which the second winding is in the leg with the circuit under test and produces a field opposing the field from the first winding.
Claim 6
Dependent Claim
31 words
A device as in claim 2, in which the second winding is responsive to said testing electrical signals and produces a field that adds to the field from the first winding.
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) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |