US3769576A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus including an oscillator for detecting short circuits in electrical components
Assignee: Individual
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Filing: 1972-06-02
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Granted: 1973-10-30
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Expires: 1992-06-02
Abstract
Abstract An apparatus for testing short circuit in electrical components such as motor or generator stators having plural windings with extremely low direct current resistance but measurable high frequency alternating current impedance. Preferably, the invention is embodied in a tester unit which includes leads for attachment to individual current windings forming a part of the article to be tested, and a transistor oscillator operated by a battery and having a display device such as a milliammeter in the output circuit in series with a diode or the like. A feedback circuit parallel with the milliammeter and the exterior load includes a center tapped inductor and a variable resistor in series with each other and controlling base current. The method includes operating the oscillator so as to produce a pulsating DC current in the output circuit, and successively connecting the exterior leads to each individual winding in the stator to be tested, and comparing the impedance readings of the windings with each other after calibrating the meter by adjusting the variable resistor to provide maximum current in the external circuit.
Inventors
- 👤 A Norkaitis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:08
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/34
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
211 words
An apparatus for testing for short circuits in an external circuit comprising plural electrical windings having relatively great impedance in relation to the direct current resistance thereof, said apparatus comprising, in combination, an oscillator circuit and means for readily detachable connection of the terminals thereof to an external circuit which includes said inductive load, said oscillator circuit including means for supplying electrical energy in the 500 to 5,000 cycle per second range to said external circuit, an output circuit, and means For controlling the current flow in said output circuit, said output circuit including an ammeter for measuring the flow of current therein and at least one diode in series with said ammeter for insuring current flow in one direction through said ammeter, said output circuit control means including a current control device operatively controlled by a feedback circuit having parallel input portions and containing a variable resistance in series with said parallel portions, each of said parallel portions having an inductance therein, with one of said parallel portions being connected to said output circuit on one side of said means for controlling current flow direction and the other of said parallel portions being connected to said output circuit on the other side of said means for controlling current flow direction.
Claim 2
Independent Claim
211 words
An apparatus for testing for short circuits in an external circuit comprising plural electrical windings having relatively great impedance in relation to the direct current resistance thereof, said apparatus comprising, in combination, an oscillator circuit and means for readily detachable connection of the terminals thereof to an external circuit which includes said inductive load, said oscillator circuit including means for supplying electrical energy in the 500 to 5,000 cycle per second range to said external circuit, an output circuit, and means For controlling the current flow in said output circuit, said output circuit including an ammeter for measuring the flow of current therein and at least one diode in series with said ammeter for insuring current flow in one direction through said ammeter, said output circuit control means including a current control device operatively controlled by a feedback circuit having parallel input portions and containing a variable resistance in series with said parallel portions, each of said parallel portions having an inductance therein, with one of said parallel portions being connected to said output circuit on one side of said means for controlling current flow direction and the other of said parallel portions being connected to said output circuit on the other side of said means for controlling current flow direction.
Claim 3
Dependent Claim
38 words
An apparatus as defined in claim 1 wherein said electrical energy supply and said internal circuit are disposed within a portable instrument, said instrument having a display means associated therewith for displaying a reading made by said ammeter.
Claim 4
Dependent Claim
26 words
An apparatus as defined in claim 1 in which said means for controlling current flow in said output circuit is in the form of a transistor.
Claim 5
Dependent Claim
19 words
An apparatus as defined in claim 1 in which two parallel connected diodes are in series with said ammeter.
Claim 6
Dependent Claim
67 words
An apparatus as defined in claim 1 in which the inductance in one of said parallel input portions of said feedback circuit comprises a first coil, and in which the inductance in the other of said parallel input portions of said feedback circuit comprises only a portion of said first coil, whereby said one feedback circuit has the same resistance but less inductance than said other circuit.
Claim 7
Dependent Claim
34 words
An apparatus as defined in claim 2, wherein said instrument includes calibration marks on said display means to facilitate retentive display of a previous reading to facilitate comparison of previous readings with later readings.
Claim 8
Dependent Claim
31 words
An apparatus as defined in claim 2 which includes switch means for rendering said internal circuit non-conductive when said instrument is attached to said external circuit but is not in use.
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) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |