US3573616A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current measuring system having a feedback path including a combined high gain amplifier and integrator
Assignee: International Business Machines Corp
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Filing: 1969-03-13
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Granted: 1971-04-06
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Expires: 1989-03-13
Abstract
Abstract A current-measuring system is provided for measuring over a wide range the flow of direct or alternating current in a conductor. The system includes a magnetic core arranged in two pieces which is clamped around the conductor for producing a magnetic field in response to current flow in the conductor. A magnetic to electric transducer, such as a Hall effect generator, is placed in a gap in the core and the output leads of the Hall effect device is connected to an operational amplifier that integrates the Hall effect signal. The operational amplifier is connected to a current driver, the output of which is connected to windings on the core. The current driver produces an output current in response to the amplifier output signal to oppose the field produced by the core. A resistor is connected between the current driver and the coil and the output voltage across the resistor is a measure of the current in the conductor.
Inventors
- 👤 Hooshang Kahen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:44
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/14; G01R15/20; G01R15/202
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
260 words
Apparatus for measuring current flowing in a conductor comprising: a core of magnetic material surrounding said conductor and having at least one air gap, said core providing a path for the magnetic field produced by said current, said core of magnetic material including first and second core pieces adapted to be placed together around said conductor; a Hall effect magnetic to electric transducer located in said air gap for producing an output voltage representative of said magnetic flux; an operational amplifier including a DC amplifier having a feedback path including a capacitor, said operational amplifier connected to said magnetic to electric transducer for integrating and phase inverting the output voltage from said magnetic to electric transducer, current means connected to the output of said operational amplifier for producing a current in response to the output voltage of said operational amplifier; and a conductive winding connected to the output of said current means and wound around said magnetic core for producing a magnetic field equal and opposite to the magnetic field produced by said conductor; and a resistor connected in series with said conductive winding and a meter connected across said resistor to measure the voltage across said resistor to provide an indication of the value of the current flowing in said conductor; and said operational amplifier integrating the output voltage of said transducer for driving said current means so as to provide a current output sufficient to cause the output voltage of said transducer to become zero and said amplifier further maintaining a voltage output representative of said magnetic flux.
Claim 2
Dependent Claim
260 words
Apparatus for measuring current flowing in a conductor comprising: a core of magnetic material surrounding said conductor and having at least one air gap, said core providing a path for the magnetic field produced by said current, said core of magnetic material including first and second core pieces adapted to be placed together around said conductor; a Hall effect magnetic to electric transducer located in said air gap for producing an output voltage representative of said magnetic flux; an operational amplifier including a DC amplifier having a feedback path including a capacitor, said operational amplifier connected to said magnetic to electric transducer for integrating and phase inverting the output voltage from said magnetic to electric transducer, current means connected to the output of said operational amplifier for producing a current in response to the output voltage of said operational amplifier; and a conductive winding connected to the output of said current means and wound around said magnetic core for producing a magnetic field equal and opposite to the magnetic field produced by said conductor; and a resistor connected in series with said conductive winding and a meter connected across said resistor to measure the voltage across said resistor to provide an indication of the value of the current flowing in said conductor; and said operational amplifier integrating the output voltage of said transducer for driving said current means so as to provide a current output sufficient to cause the output voltage of said transducer to become zero and said amplifier further maintaining a voltage output representative of said magnetic flux.
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) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |