US3644783A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dc detection circuit
Assignee: Esquire Inc
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Filing: 1969-08-18
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Granted: 1972-02-22
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Expires: 1989-08-18
Abstract
Abstract A DC detection circuit in an AC power circuit for detecting DC and for protecting AC loads from the deleterious application of a DC current. The DC detection circuit is particularly applicable to an emergency lighting system having both AC and DC power sources and AC and DC lighting facilities for detecting the application of DC and for disconnecting the AC lighting facilities to prevent their damage and for lighting the DC lighting facilities.
Inventors
- 👤 Carl R Snyder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 01:54
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/50; H02J; H02J9/00; H02J9/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
108 words
In an AC power circuit having at least one AC load connected to an AC power source, said AC load capable of being deleteriously affected by the application of a DC voltage thereto, a DC detecting circuit comprising: gated switch means connected across said AC load; integrator circuit means having an input connected to said AC voltage source and an output; trigger means responsive to the output of said integrator circuit indicating the application of a DC power for applying a gating voltage to said gated switch means; and means responsive to the conduction of said gated switch means for disconnecting said AC load from said AC source.
Claim 2
Dependent Claim
108 words
In an AC power circuit having at least one AC load connected to an AC power source, said AC load capable of being deleteriously affected by the application of a DC voltage thereto, a DC detecting circuit comprising: gated switch means connected across said AC load; integrator circuit means having an input connected to said AC voltage source and an output; trigger means responsive to the output of said integrator circuit indicating the application of a DC power for applying a gating voltage to said gated switch means; and means responsive to the conduction of said gated switch means for disconnecting said AC load from said AC source.
Claim 3
Dependent Claim
63 words
A DC detecting circuit as described in claim 1, wherein, said integrator circuit means includes a series combination of a resistance and a capacitance, and said trigger means has a threshold voltage level greater than the maximum voltage of said AC source, said trigger means connected between the gate of said gated switch means and the juncture of said resistance and said capacitance.
Claim 4
Dependent Claim
36 words
A DC detecting circuit as described in claim 1, wherein said disconnecting means includes: fuse means which are responsive to the conduction of said gated switch means for disconnecting said AC load from said AC source.
Claim 5
Dependent Claim
137 words
In an AC power circuit having at least one AC load connected to an AC power source, said AC load capable of being deleteriously affected by the application of a DC voltage thereto, an AC/DC signalling circuit comprising: AC signalling means connected across said AC load for indicating the presence of an AC voltage, a series combination of DC signalling means and gated switch means, said series combination connected across said AC load; integrator circuit means having an input connected to said AC source and an output; and trigger means responsive to said output of said integrator circuit indicating the application of a DC voltage for applying a gating voltage to said gated switch means to energize said DC signalling means (and means responsive to the application of a DC voltage for deenergizing said AC signalling means).
Claim 6
Dependent Claim
137 words
In an AC power circuit having at least one AC load connected to an AC power source, said AC load capable of being deleteriously affected by the application of a DC voltage thereto, an AC/DC signalling circuit comprising: AC signalling means connected across said AC load for indicating the presence of an AC voltage, a series combination of DC signalling means and gated switch means, said series combination connected across said AC load; integrator circuit means having an input connected to said AC source and an output; and trigger means responsive to said output of said integrator circuit indicating the application of a DC voltage for applying a gating voltage to said gated switch means to energize said DC signalling means (and means responsive to the application of a DC voltage for deenergizing said AC signalling means).
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) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |