US3921069A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable gain electronic current transformer
Assignee: General Electric Co
•
Filing: 1974-11-06
•
Granted: 1975-11-18
•
Expires: 1994-11-06
Abstract
Abstract A variable gain electronic current transformer is disclosed which includes means for detecting the current flow into a power consuming system. An operational amplifier amplifies the detected current and the output of the operational amplifier is converted into a magnetic flux field which is directed onto one surface of a Hall effect element. A variable current source supplies current to a second orthogonal surface of the Hall effect element to thereby generate an output voltage which is directly proportional to the product of the output of the operational amplifier and the variable current source. This output voltage from the Hall effect element is coupled back to the input of the operational amplifier. A second Hall effect element is positioned in the flux field generated at the output of the operational amplifier and in addition has a second variable current source coupled to one surface thereof so that the output of the second Hall effect element is a voltage which is proportional to the product of the output of the operational amplifier and the second variable current source. Accordingly, the output voltage of the second Hall effect element is directly proportional to the product of the detected current and the output of the second current source and is inversely proportional to the output of the first variable current source to thereby provide a current transformer having a large dynamic range depending upon the variance of the outputs of the first and second variable current sources.
Inventors
- 👤 Miran Milkovic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:42
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/08; G01R19/00; G01R19/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
367 words
An apparatus for metering active electrical energy in a polyphase three-line system comprising: means for measuring current in at least twO of said lines, each of said current measuring means including means for sensing the current flow through said line, operational amplifier means for amplifying said sensed current, a first source of variable current, means responsive to the output of said variable current source and said amplifier for generating a feedback voltage having a magnitude which is proportional to the product of the output of said variable current source and the output of said amplifier, said feedback voltage being coupled to the input of said operational amplifier, a second source of variable current, means responsive to the output of said operational amplifier and said second current source for generating an output voltage, said output voltage being proportional to said sensed voltage and being directly variable in accordance with the output of said second current source and inversely variable in accordance with said first current source, means for measuring two different line voltages, means coupled with said current measuring means for producing a first plurality of two analog signals representing the currents measured in the two lines, means coupled with the voltage measuring means for producing a second plurality of at least two analog signals representing the different line voltages, means for pairing different ones of the current analog signals of the first plurality with different ones of voltage analog signals of the second plurality such that the different pairs representative of the instantaneous power in different parts of said polyphase system, means coupled with said pairing means for converting each of the pairs of analog signals to a different one of a series of consecutive signals, each signal in each of the series representing instantaneous power in a different part of said system, means coupled with said lastmentioned conversion means for converting said signals in said series of consecutive signals to a signal representing average power in the system, an analog to pulse rate converter for converting said average power signal to an output pulse train having a frequency which is proportional to the magnitude of said average power signal, and means for recording said pulse trains.
Claim 2
Independent Claim
367 words
An apparatus for metering active electrical energy in a polyphase three-line system comprising: means for measuring current in at least twO of said lines, each of said current measuring means including means for sensing the current flow through said line, operational amplifier means for amplifying said sensed current, a first source of variable current, means responsive to the output of said variable current source and said amplifier for generating a feedback voltage having a magnitude which is proportional to the product of the output of said variable current source and the output of said amplifier, said feedback voltage being coupled to the input of said operational amplifier, a second source of variable current, means responsive to the output of said operational amplifier and said second current source for generating an output voltage, said output voltage being proportional to said sensed voltage and being directly variable in accordance with the output of said second current source and inversely variable in accordance with said first current source, means for measuring two different line voltages, means coupled with said current measuring means for producing a first plurality of two analog signals representing the currents measured in the two lines, means coupled with the voltage measuring means for producing a second plurality of at least two analog signals representing the different line voltages, means for pairing different ones of the current analog signals of the first plurality with different ones of voltage analog signals of the second plurality such that the different pairs representative of the instantaneous power in different parts of said polyphase system, means coupled with said pairing means for converting each of the pairs of analog signals to a different one of a series of consecutive signals, each signal in each of the series representing instantaneous power in a different part of said system, means coupled with said lastmentioned conversion means for converting said signals in said series of consecutive signals to a signal representing average power in the system, an analog to pulse rate converter for converting said average power signal to an output pulse train having a frequency which is proportional to the magnitude of said average power signal, and means for recording said pulse trains.
Claim 3
Dependent Claim
106 words
The apparatus of claim 1 wherein said means responsive to the output of said variable current source and said amplifier for generating a feedback voltage comprises a Hall effect device, and means for generating the output of said operational amplifier into a flux field having a magnitude proportional to the output of said operational amplifier, said flux field being directed through one plane of said Hall effect device and said output of said variable gain source being directed through a second orthogonal plane of said Hall effect device, the output voltage of said Hall effect device being coupled back to the input of said operational amplifier.
Claim 4
Dependent Claim
110 words
The apparatus of claim 2 wherein said means responsive to the output of said operational amplifier and said second current source comprises a second Hall effect element, the magnetic field generated by the output of said operational amplifier being directed through one plane of said second Hall effect element and the output of said second variable current source being directed through a second orthogonal plane of said Hall effect element wherein the output of said second Hall effect element is directly proportional to said sensed voltage and is directly variable in accordance with the output of said second current source and inversely variable in accordance with said first current source.
Claim 5
Dependent Claim
26 words
The apparatus of claim 3 wherein said Hall effect elements are substantially identical and wherein said Hall effect elements are formed on the same semiconductor chip.
Claim 6
Dependent Claim
47 words
The apparatus of claim 4 further comprising means for varying the output of said second current source inversely with said sensed current flow and means for correspondingly reducing the amplification factor of said apparatus for metering active electrical energy to theReby provide a constant system gain factor.
Claim 7
Independent Claim
365 words
An apparatus for metering active electrical energy in a polyphase N-line system comprising: means for measuring current in at least N-1 of said lines, each of said current measuring means including means for sensing the current flow through said line, operational amplifier means for amplifying said sensed current, a first source of variable current, means responsive to the output of said variable current source and said amplifier for generating a feedback voltage having a magnitude which is proportional to the product of the output of said variable current source and the output of said amplifier, said feedback voltage being coupled to the input of said operational amplifier, a second source of variable current, means responsive to the output of said operational amplifier and said second current source for generating an output voltage, said output voltage being proportional to said sensed voltage and being directly variable in accordance with the output of said second current source and inversely variable in accordance with said first current source, means for measuring N-1 different line voltages, means coupled with said current measuring means for producing a first plurality of N-1 analog signals representing the currents measured in the N lines, means coupled with the voltage measuring means for producing a second plurality of N-1 analog signals representing the different line voltages, means for pairing different ones of the current analog signals of the first plurality with different ones of voltage analog signals of the second plurality such that the different pairs representative of the instantaneous power in different parts of said polyphase system, means coupled with said pairing means for converting each of the pairs of analog signals to a different one of a series of consecutive signals, each signal in each of the series representing instantaneous power in a different part of said system, means coupled with said last-mentioned conversion means for converting said signals in said series of consecutive signals to a signal representing average power in the system, an analog to pulse rate converter for converting said average power signal to an output pulse train having a frequency which is proportional to the magnitude of said average power signal, and means for recording said pulse trains.
Claim 8
Independent Claim
365 words
An apparatus for metering active electrical energy in a polyphase N-line system comprising: means for measuring current in at least N-1 of said lines, each of said current measuring means including means for sensing the current flow through said line, operational amplifier means for amplifying said sensed current, a first source of variable current, means responsive to the output of said variable current source and said amplifier for generating a feedback voltage having a magnitude which is proportional to the product of the output of said variable current source and the output of said amplifier, said feedback voltage being coupled to the input of said operational amplifier, a second source of variable current, means responsive to the output of said operational amplifier and said second current source for generating an output voltage, said output voltage being proportional to said sensed voltage and being directly variable in accordance with the output of said second current source and inversely variable in accordance with said first current source, means for measuring N-1 different line voltages, means coupled with said current measuring means for producing a first plurality of N-1 analog signals representing the currents measured in the N lines, means coupled with the voltage measuring means for producing a second plurality of N-1 analog signals representing the different line voltages, means for pairing different ones of the current analog signals of the first plurality with different ones of voltage analog signals of the second plurality such that the different pairs representative of the instantaneous power in different parts of said polyphase system, means coupled with said pairing means for converting each of the pairs of analog signals to a different one of a series of consecutive signals, each signal in each of the series representing instantaneous power in a different part of said system, means coupled with said last-mentioned conversion means for converting said signals in said series of consecutive signals to a signal representing average power in the system, an analog to pulse rate converter for converting said average power signal to an output pulse train having a frequency which is proportional to the magnitude of said average power signal, and means for recording said pulse trains.
Claim 9
Dependent Claim
106 words
The apparatus of claim 6 wherein said means responsive to the output of said variable current source and said amplifier for generating a feedback voltage comprises a Hall effect device, and means for generating the output of said operational amplifier into a flux field having a magnitude proportional to the output of said operational amplifier, said flux field being directed though one plane of said Hall effect device and said output of said variable gain source being directed through a second orthogonal plane of said Hall effect device, the output voltage of said Hall effect device being coupled back to the input of said operational amplifier.
Claim 10
Dependent Claim
110 words
The apparatus of claim 7 wherein said means responsive to the output of said operational amplifier and said second current source comprises a second Hall effect element, the magnetic field generated by the output of said operational amplifier being directed through one plane of said second Hall effect element and the output of said second variable current source being directed through a second orthogonal plane of said Hall effect element wherein the output of said second Hall effect element is directly proportional to said sensed voltage and is directly variable in accordance with the output of said second current source and inversely variable in accordance with said first current source.
Claim 11
Dependent Claim
26 words
The apparatus of claim 8 wherein said Hall effect elements are substantially identical and wherein said Hall effect elements are formed on the same semiconductor chip.
Claim 12
Dependent Claim
47 words
The apparatus of claim 9 further comprising means for varying the output of said second current source inversely with said sensed current flow and means for correspondingly reducing the amplification factor of said apparatus for metering active electrical energy to thereby provide a constant system gain factor.
References Cited (Backward Citations)
US3343084A
Cited
US3718860A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |