US4028737A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transient voltage protection circuit
Assignee: Schneider Electric Buildings Americas Inc
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Filing: 1975-04-02
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Granted: 1977-06-07
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Expires: 1995-04-02
Abstract
Abstract A triac controlling current from an AC line to a load is protected against excessive transient voltages on the line by a protection circuit that turns on the triac when excessive positive or negative transient voltages occur so that the resultant power is dissipated in the controlled load.
Inventors
- 👤 Ronald L. Bailey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 02:05
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0824; H02; H02H; H02H7/00; H02H7/10; H02H7/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
128 words
A transient voltage protection circuit for a thyristor connected through the power and common terminals thereof in series with a load controlled thereby and an AC power supply, said circuit comprising a voltage divider and said thyristor through the power and common terminals thereof in parallel circuits, a tap on the voltage divider providing a control voltage as a function of the instantaneous voltage on said AC supply, a source of regulated DC reference voltage at a magnitude below the control voltage corresponding to a thyristor destructive voltage on said AC supply, a source of turn-on voltage, and means for selectively coupling said thyristor through a gate and the common terminal thereof across the source of turn-on voltage in response to said control voltage exceeding the reference voltage.
Claim 2
Dependent Claim
128 words
A transient voltage protection circuit for a thyristor connected through the power and common terminals thereof in series with a load controlled thereby and an AC power supply, said circuit comprising a voltage divider and said thyristor through the power and common terminals thereof in parallel circuits, a tap on the voltage divider providing a control voltage as a function of the instantaneous voltage on said AC supply, a source of regulated DC reference voltage at a magnitude below the control voltage corresponding to a thyristor destructive voltage on said AC supply, a source of turn-on voltage, and means for selectively coupling said thyristor through a gate and the common terminal thereof across the source of turn-on voltage in response to said control voltage exceeding the reference voltage.
Claim 3
Dependent Claim
27 words
A transient voltage protection circuit according to claim 1 additionally comprising a bias voltage source in series with the voltage divider in said circuit paralleling the thyristor.
Claim 4
Dependent Claim
112 words
A transient voltage protection circuit according to claim 1 additionally comprising a second voltage divider and a bias voltage source in a series circuit, said series circuit and the thyristor through the power and common terminals thereof in parallel circuits, a second tap on said second voltage divider providing a second control voltage as a function of the instantaneous voltage on said AC supply, and second means for selectively coupling said thyristor through the gate and the common terminal thereof across the source of turn-on voltage in response to said DC reference voltage exceeding the second control voltage upon occurrence of an excessive transient voltage of reverse polarity on said AC supply.
Claim 5
Dependent Claim
38 words
A transient voltage protection circuit according to claim 1 wherein a comparator receiving inputs from said sources of DC reference and control voltage provides at an output terminal as an output a signal to which said means responds.
Claim 6
Dependent Claim
26 words
A transient voltage protection circuit according to claim 4 wherein said means couples the output terminal of said comparator to the gate terminal of said thyristor.
Claim 7
Dependent Claim
45 words
A transient voltage protection circuit according to claim 4 wherein said means comprises a switching device connected to deliver the turn-on voltage from the source thereof to said gate terminal of the thyristor in response to a signal received from the output of said comparator.
Claim 8
Dependent Claim
16 words
A transient voltage protection circuit according to claim 6, wherein said switching device comprises a transistor.
Claim 9
Dependent Claim
15 words
A transient voltage protection circuit according to claim 4 wherein said comparator comprises a transistor.
Claim 10
Dependent Claim
21 words
A transient voltage protection circuit according to claim 1 wherein the sources of the DC reference and turn-on voltages are one.
References Cited (Backward Citations)
US3603843A
Cited
US3769548A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-06-06 | 1980-12-06 | 1981-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-06 | 1984-12-06 | 1985-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-06 | 1988-12-06 | 1989-06-07 | $7700.00 | Window Closed / Lapsed |