US4090127A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for measuring with direct current the total resistance of a circuit when there is also present an alternative component from the mains
Assignee: Individual
•
Filing: 1976-09-23
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Granted: 1978-05-16
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Expires: 1996-09-23
Abstract
Abstract Instrument for measuring the total resistance of the protection circuit, that is to say of the phase-to-earth circuit the electric shock may possibly pass through. The modification made in Wheatstone's bridge (two condenser placed between the couples of vertices) allows a side of the bridge to be replaced through a circuit containing electromotive force. However, the alternate voltages involved do influence neither the direct ones utilized for measuring the unknown earth resistance nor the zero-instrument. Feeding is carried out through a Graetz bridge, to which a suitable resistance was added to avoid short-circuits on a side of the same bridge.
Inventors
- 👤 Augusto Giustini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:46
CPC Classifications
G; G01; G01R; G01R17/00; G01R17/10; G01R17/105
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
157 words
An instrument for measuring the total resistance of a circuit comprising: a Wheatstone bridge circuit having the circuit whose resistance is to be measured connected as one leg thereof; a resistor having a first terminal and a second terminal; a bridge rectifier circuit having a first pair of diagonally opposite junctions, one of which is connected to said resistor first terminal, the other of said first pair of diagonally opposite junctions and said resistor second terminal adapted for connection across an alternating voltage source to be supplied with alternating voltage therefrom, said bridge rectifier circuit further having a second pair of diagonally opposite junctions connected across two diagonally opposite junctions of said Wheatstone bridge circuit to supply rectified voltage thereto, whereby said Wheatstone bridge circuit is energized; a first capacitor coupled across said two diagonally opposite junctions of said Wheatstone bridge circuit; and a second capacitor coupled across the null indicating device of said wheatstone bridge circuit.
Claim 2
Dependent Claim
157 words
An instrument for measuring the total resistance of a circuit comprising: a Wheatstone bridge circuit having the circuit whose resistance is to be measured connected as one leg thereof; a resistor having a first terminal and a second terminal; a bridge rectifier circuit having a first pair of diagonally opposite junctions, one of which is connected to said resistor first terminal, the other of said first pair of diagonally opposite junctions and said resistor second terminal adapted for connection across an alternating voltage source to be supplied with alternating voltage therefrom, said bridge rectifier circuit further having a second pair of diagonally opposite junctions connected across two diagonally opposite junctions of said Wheatstone bridge circuit to supply rectified voltage thereto, whereby said Wheatstone bridge circuit is energized; a first capacitor coupled across said two diagonally opposite junctions of said Wheatstone bridge circuit; and a second capacitor coupled across the null indicating device of said wheatstone bridge circuit.
Claim 3
Dependent Claim
59 words
An instrument as claimed in claim 1 further comprising an alternating voltage source coupled across said other of said bridge rectifier circuit first pair of diagonally opposite junctions and said resistor second terminal and having the alternating voltage source ground return resistance connected as said one leg of said Wheatstone bridge circuit for measurement of said ground return resistance.
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) | 1981-05-15 | 1981-11-14 | 1982-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-15 | 1985-11-14 | 1986-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-15 | 1989-11-14 | 1990-05-16 | $7700.00 | Window Closed / Lapsed |