US3881118A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic switching circuits
Assignee: National Research Development Corp UK
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Filing: 1973-08-17
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Granted: 1975-04-29
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Expires: 1993-08-17
Abstract
Abstract Apparatus for use as a switch in series with an alternating current supply, including a bi-directional rectifier combination (for example a pair of thyristors); a bridge rectifier circuit; two resistors each of which is connected between a separate one of the input terminals of the bridge rectifier circuit and a separate one of the main terminals of the bi-directional rectifier combination; at least one electrical connection from an input terminal of the bridge rectifier circuit to a trigger electrode of the bi-directional rectifier combination; and, a control circuit of controllable conductivity connected across the output terminals of the bridge rectifier circuit. The switching circuits described close only when the supply voltage is zero and open only when the supply current is zero. An application of the circuits is described in which a conventional electro-mechanical switch and one such electronic switching circuit are connected in parallel, and their switching operations are controlled by a suitable control circuit to provide the transient-free loadswitching characteristic of the electronic switching circuit as well as the low voltage loss characteristic of the electromechanical switch under steady state conditions.
Inventors
- 👤 Robert Henry Forrest
- 👤 Reginald John Kingston Splatt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:46
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/78; H03K17/79; H03K17/56; H03K17/72; H03K17/725; H03K2217/00; H03K2217/0036; Y; Y10; Y10S; Y10S323/00; Y10S323/902
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
253 words
An electronic switching circuit for controlling a supply of alternating current electricity to a load comprising: a bidirectional rectifier combination; a bridge rectifier circuit; two resistors each of which is connected between a separate one of the input terminals of the bridge rectifier circuit and a separate one of the main terminals of the bi-directional rectifier combination; at least one electrical connection from an input terminal of the bridge rectifier circuit to a trigger electrode of the bi-directional combination; a switchable semiconductor device having a control current path and a main current path which may be switched to a conductive state by drawing current through the control current path, the main current path being connected across the output terminals of the bridge rectifier circuit, and a control circuit means for controlling the current in the said control current path characterized in that the control circuit means comprises a transistor whose emitter-to-collector current path is connected in series with the said control current path of the switchable semiconductor device and whose base is connected to receive a full-wave rectified waveform from the bridge rectifier circuit; a source of direct current voltage; and, first control means for applying a direct current voltage from the said source to the emitter of the said transistor to cause the said transistor to become conductive whenever the said full-wave rectified waveform approaches zero voltage and then to maintain a continuous control current in the control current path of the switchable semiconductor device Until the first control means is reset.
Claim 2
Dependent Claim
253 words
An electronic switching circuit for controlling a supply of alternating current electricity to a load comprising: a bidirectional rectifier combination; a bridge rectifier circuit; two resistors each of which is connected between a separate one of the input terminals of the bridge rectifier circuit and a separate one of the main terminals of the bi-directional rectifier combination; at least one electrical connection from an input terminal of the bridge rectifier circuit to a trigger electrode of the bi-directional combination; a switchable semiconductor device having a control current path and a main current path which may be switched to a conductive state by drawing current through the control current path, the main current path being connected across the output terminals of the bridge rectifier circuit, and a control circuit means for controlling the current in the said control current path characterized in that the control circuit means comprises a transistor whose emitter-to-collector current path is connected in series with the said control current path of the switchable semiconductor device and whose base is connected to receive a full-wave rectified waveform from the bridge rectifier circuit; a source of direct current voltage; and, first control means for applying a direct current voltage from the said source to the emitter of the said transistor to cause the said transistor to become conductive whenever the said full-wave rectified waveform approaches zero voltage and then to maintain a continuous control current in the control current path of the switchable semiconductor device Until the first control means is reset.
Claim 3
Dependent Claim
60 words
An electronic switching circuit as claimed in claim 1 and wherein the source of direct current voltage comprises a further rectifier circuit, and a resistor and a Zener diode connected in series across the output of the rectifier circuit, and the said first control means comprises means for applying the voltage developed across the Zener diode to the said transistor.
Claim 4
Dependent Claim
20 words
An electronic switching circuit as claimed in claim 2 and wherein the said first control means comprises an opto-electronic isolator.
Claim 5
Dependent Claim
30 words
An electronic switching circuit as claimed in claim 2 and wherein the further rectifier circuit is a voltage-multiplying circuit having input connections connected in parallel with the bi-directional rectifier combination.
Claim 6
Dependent Claim
56 words
An electronic switching circuit including an electro-mechanical switch connected in parallel with an electronic switching circuit as claimed in claim 1 and second control means connected to the electro-mechanical switch and to the electronic switching circuit for ensuring that the electronic switching circuit closes before the electro-mechanical switch closes and opens after the electro-mechanical switch opens.
Claim 7
Dependent Claim
100 words
An electronic switching circuit as claimed in claim 5 and wherein the said second control means comprises first delay means connected to the electro-mechanical switch and second delay means connected to the electronic switching circuit for providing corresponding first and second delays respectively said first and second delays being chosen such that the electronic switching circuit will not carry substantially more than half a cycle of the alternating current supply when closed before the electro-mechanical switch is closed and will not carry substantially more than half a cycle of the alternating current supply after the electro-mechanical switch has been opened.
References Cited (Backward Citations)
US3381226A
Cited
US3723769A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |