US3798543A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direct current ratio measuring apparatus
Assignee: Advantest Corp
•
Filing: 1972-12-18
•
Granted: 1974-03-19
•
Expires: 1992-12-18
Abstract
Abstract This invention relates to a direct current ratio measuring apparatus wherein the current ratio is determined by first making a reference current and then making an unknown current to be measured flow through an input winding wound on a magnetic core of high magnetic permeability and in each case automatically cancelling out the flux in the core by introducing cancelling currents into another winding on the core, these cancelling currents being measurable to determine the ratio without introducing errors therein as occurs if an attempt is made to directly measure the reference and unknown currents.
Inventors
- 👤 I Takeda
- 👤 T Suzuki
- 👤 H Furukawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:15
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/10; G01R1/00; G01R1/28
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
229 words
Apparatus for measuring the ratio of an unknown direct current and a known reference current from a stable source, comprising a magnetic core; an input winding, a magnetic-flux cancelling winding, and a magnetic flux detecting element, the windings being wound on said core; means coupled to said flux detecting element to develop an output voltage of polarity and magnitude representative of the flux in the core; a coefficient multiplier device for multiplying said output voltage by a coefficient to generate a cancelling current and pass it through said flux cancelling winding to cancel the flux in the core; a voltmeter for measuring said output voltage; and multi-step controller means operative in a first step to set the coefficient multiplier device at unity and to introduce the known reference current into the input winding while the voltmeter reads the initial value of said output voltage required to cancel the flux in the core; said controller means being operative in a subsequent step to introduce said unknown current into the input winding and to set the coefficient multiplier device to multiply the resulting output voltage by a coefficient proportional to the initial value of said output voltage while the voltmeter reads the new value of output voltage required to cancel the flux in the core, said new value being proportional to the ratio of the unknown and the reFerence currents introduced.
Claim 2
Dependent Claim
229 words
Apparatus for measuring the ratio of an unknown direct current and a known reference current from a stable source, comprising a magnetic core; an input winding, a magnetic-flux cancelling winding, and a magnetic flux detecting element, the windings being wound on said core; means coupled to said flux detecting element to develop an output voltage of polarity and magnitude representative of the flux in the core; a coefficient multiplier device for multiplying said output voltage by a coefficient to generate a cancelling current and pass it through said flux cancelling winding to cancel the flux in the core; a voltmeter for measuring said output voltage; and multi-step controller means operative in a first step to set the coefficient multiplier device at unity and to introduce the known reference current into the input winding while the voltmeter reads the initial value of said output voltage required to cancel the flux in the core; said controller means being operative in a subsequent step to introduce said unknown current into the input winding and to set the coefficient multiplier device to multiply the resulting output voltage by a coefficient proportional to the initial value of said output voltage while the voltmeter reads the new value of output voltage required to cancel the flux in the core, said new value being proportional to the ratio of the unknown and the reFerence currents introduced.
Claim 3
Dependent Claim
150 words
A direct current ratio measuring apparatus according to claim 1 including a second magnetic flux cancelling winding having a variable number of turns, wherein while said unknown direct current is introduced into said input winding, and said new value of said output voltage required to cancel the magnetic flux in the magnetic core is read by the voltmeter, said multi-step controller means is operative in a third step to set the number of turns of said second magnetic flux cancelling winding at a value corresponding to the output voltage value resulting when said unknown current is introduced into said input winding, said first flux cancelling winding has a fixed number of turns and is connected to said coefficient multiplier device through a resistance, and said voltmeter measures and indicates said resulting output voltage value as a more significant figure and said new output voltage value as a less significant figure.
References Cited (Backward Citations)
US2919067A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |