Patent US3745375A successfully refreshed from Google Patents.
US3745375A
Expired / Lapsed
US
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Phase unbalance or open-phase detecting apparatus
Assignee: Meidensha Electric Manufacturing Co Ltd
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Filing: 1971-12-01
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Granted: 1973-07-10
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Expires: 1991-12-01
Abstract
Abstract A plurality of current transformers have primary windings connected to a phase signal circuit and secondary winding each having a plurality of terminals, respectively. One terminal of the secondary windings is connected to a positive direct signal generating means in common to said current transformers so that a constant voltage signal is held thereat when there is at least one of the phase signals in a normal condition. The other terminals of the secondary windings are connected to a plurality of negative direct signal generating means which are the same in number as said current transformers. Difference signals are derived from the outputs of the positive direct signal generating means and the negative direct signals generating means. The variation of the difference signals indicate the phase unbalanced or open-phase signal.
Inventors
- 👤 M Huruse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:44
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/32; H02H3/34
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
209 words
Apparatus for detecting a phase-current imbalance or openphase condition in a polyphase circuit, which comprises: a plurality of current transformers, each having a primary winding connected in one of the phases of said polyphase circuit and a center-tapped secondary winding; first rectifying means, connected to one terminal of each of said plurality of secondary windings, for developing a smoothed d.c. signal of a first polarity between the rectifying means and said center-tap; a plurality of second rectifying means, each connected to the other terminal of a corresponding secondary winding, for developing at least one smoothed d.c. signal voltage between at least one of the second rectifying means and said center-tap, said signal voltage being proportional to the alternating current in a corresponding phase and opposite in polarity to the signal of said first polarity; means, connected to said first rectifying means and to each of said plurality of second rectifying means, for developing at least one difference signal corresponding to the voltage difference between said d.c. signal of a first polarity and said at least one d.c. signal of a second polarity; and detecting means, responsive to said difference signal, for detecting an imbalance in the current value or an open-phase condition in any one of said polyphase lines.
Claim 2
Dependent Claim
209 words
Apparatus for detecting a phase-current imbalance or openphase condition in a polyphase circuit, which comprises: a plurality of current transformers, each having a primary winding connected in one of the phases of said polyphase circuit and a center-tapped secondary winding; first rectifying means, connected to one terminal of each of said plurality of secondary windings, for developing a smoothed d.c. signal of a first polarity between the rectifying means and said center-tap; a plurality of second rectifying means, each connected to the other terminal of a corresponding secondary winding, for developing at least one smoothed d.c. signal voltage between at least one of the second rectifying means and said center-tap, said signal voltage being proportional to the alternating current in a corresponding phase and opposite in polarity to the signal of said first polarity; means, connected to said first rectifying means and to each of said plurality of second rectifying means, for developing at least one difference signal corresponding to the voltage difference between said d.c. signal of a first polarity and said at least one d.c. signal of a second polarity; and detecting means, responsive to said difference signal, for detecting an imbalance in the current value or an open-phase condition in any one of said polyphase lines.
Claim 3
Dependent Claim
74 words
Apparatus according to claim 1, wherein said first rectifying means comprises a plurality of similarly-poled half-wave rectifiers, each having one electrode connected to one terminal of a corresponding secondary winding and the other electrode connected to a common smoothing circuit; and said second rectifying means comprises a plurality of center-tapped full-wave rectifiers corresponding to the Respective phases and each connected to the terminals of a corresponding secondary winding and to an associated smoothing circuit.
Claim 4
Dependent Claim
44 words
Apparatus according to claim 1, wherein the center-tap of each secondary winding is connected in common to a source of reference potential of said detecting means and said d.c. signals of said first and second polarity are measured with respect to said reference potential.
Claim 5
Dependent Claim
47 words
Apparatus according to claim 2, wherein said half-wave rectifiers comprise semiconductor diodes, and said common smoothing circuit comprises a resistor and a capacitor; and said full-wave rectifiers each comprise a pair of similarly-poled semiconductor diodes and said associated smoothing circuits each comprise a resistor and a capacitor.
Claim 6
Dependent Claim
49 words
Apparatus according to claim 1, wherein said detecting means comprises: a plurality of normally non-conducting transistors each receiving on the base circuit thereof a corresponding one of said plurality of difference signals; and an AND-gate having a plurality of inputs, each connected to the collector of a corresponding transistor.
Claim 7
Dependent Claim
41 words
Appparatus according to claim 1, wherein said detecting means comprises: an OR-gate having a plurality of inputs each receiving a corresponding one of said difference signals; and a Schmitt trigger circuit having its input connected to the output of said OR-gate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |