Patent US4670810A successfully refreshed from Google Patents.
US4670810A
Expired / Lapsed
US
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Zero-current a.c. switching system
Assignee: ELECTRONIC INSTRUMENT & SPECIALTY CORP 42 PLEASANT STREET STONEHAM MA 02180 A CORP OF MA
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Filing: 1986-03-17
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Granted: 1987-06-02
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Expires: 2006-03-17
Abstract
Abstract A zero-current a.c. switching system is provided for controlling actuation of relay contacts between a power supply and a load. A primary switch selectively energizes the relay to maintain the relay contacts in the closed state. The load current flowing through the relay contacts to the load is sensed. A secondary switch responds to the sensed load current for normally conducting to energize the relay in parallel with the primary switch. The secondary switch ceases conducting each time the load current drops below a predetermined level to cease energizing the relay and open the relay contacts the next time the load current drops below the predetermined level following the opening of the primary switch.
Inventors
- 👤 Bjorn E. Valeur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:17
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/78; H03K17/795; H03K17/7955; H03K17/13; H03K17/56; H03K17/60; H03K17/601
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
117 words
A zero-current a.c. switching system for controlling actuation of relay contacts between a power supply and a load comprising: means for sensing the load current flowing through the relay contacts to the load; primary switching means for selectively energizing the relay to maintain the relay contacts in the closed state; and secondary switching means, responsive to said means for sensing, for normally conducting to energize the relay in parallel with said primary switching means, and for ceasing conducting each time the load current drops below a predetermined level to cease energizing the relay and open the relay contacts the next time the load current drops below said predetermined level following the opening of said primary switching means.
Claim 2
Dependent Claim
117 words
A zero-current a.c. switching system for controlling actuation of relay contacts between a power supply and a load comprising: means for sensing the load current flowing through the relay contacts to the load; primary switching means for selectively energizing the relay to maintain the relay contacts in the closed state; and secondary switching means, responsive to said means for sensing, for normally conducting to energize the relay in parallel with said primary switching means, and for ceasing conducting each time the load current drops below a predetermined level to cease energizing the relay and open the relay contacts the next time the load current drops below said predetermined level following the opening of said primary switching means.
Claim 3
Dependent Claim
52 words
The switching system of claim 1 in which said means for sensing includes diode means, responsive to a load current of at least said predetermined level, for providing a drive signal and LED means, responsive to said drive signal, for emitting radiation to maintain said secondary switching means in the conducting condition.
Claim 4
Dependent Claim
23 words
The switching system of claim 2 in which said diode means includes first and second diodes connected in parallel and with reverse polarity.
Claim 5
Dependent Claim
23 words
The switching system of claim 2 in which said LED means includes first and second LEDs connected in parallel and with reverse polarity.
Claim 6
Dependent Claim
28 words
The switching system of claim 2 in which said secondary switching means includes semiconductor means, responsive to the radiation from said LED means, for maintaining said conducting condition.
Claim 7
Dependent Claim
20 words
The switching system of claim 5 in which said LED means and said semiconductor means are included in an optocoupler.
Claim 8
Dependent Claim
40 words
The switching system of claim 1 in which said means for sensing includes LED means, responsive to a load current of at least a said predetermined level, for emitting radiation to maintain said secondary switching means in the conducting condition.
Claim 9
Dependent Claim
22 words
The system of claim 7 in which said LED means includes first and second LEDs connected in parallel and with reverse polarity.
Claim 10
Dependent Claim
36 words
The system of claim 1 in which said means for sensing includes means for inducing an output current representative of the load current and means, responsive to said means for inducing, for providing an actuating signal.
Claim 11
Dependent Claim
17 words
The system of claim 9 in which said means for providing an actuating signal includes amplifier means.
Claim 12
Dependent Claim
25 words
The switching system of claim 9 in which said secondary switching means includes semiconductor means, responsive to said actuating signal, for maintaining said conducting condition.
Claim 13
Dependent Claim
15 words
The switching system of claim 1 in which said secondary switching means include semiconductor means.
Claim 14
Dependent Claim
39 words
The switching system of claim 1 further including impedance means connected to said secondary switching means for controlling the current through said secondary switching means in said conducting condition and for controlling the duration of the zero-current cross over.
Claim 15
Dependent Claim
16 words
The switching system of claim 1 in which said primary switching means includes a mechanical switch.
Claim 16
Dependent Claim
17 words
The switching system of claim 1 in which said primary switching means includes a solid state switch.
Claim 17
Dependent Claim
47 words
The switching system of claim 1 in which said secondary switching means switches repeatedly from said conducting condition to said non-conducting condition at a rate which equals twice the frequency of the load current so that the relay contacts are always ready for virtually instantaneous zero-current switching.
Claim 18
Dependent Claim
138 words
A zero-current a.c. switching system for controlling actuation of relay contacts between a power supply and a load comprising: diode means, responsive to a load current of at least a predetermined level, for providing a drive signal; LED means responsive to said drive signal for emitting radiation; primary switching means for selectively energizing the relay to maintain the relay contacts in the closed state; and secondary switching means, including semiconductor means responsive to said emission of radiation from said LED means, for maintaining a conducting condition to energize the relay in parallel with said primary switching means, and for ceasing conducting each time said LED means ceases emitting radiation to cease energizing the relay and open the relay contacts the next time the load current drops below said predetermined level following the opening of said primary switching means.
Claim 19
Dependent Claim
138 words
A zero-current a.c. switching system for controlling actuation of relay contacts between a power supply and a load comprising: diode means, responsive to a load current of at least a predetermined level, for providing a drive signal; LED means responsive to said drive signal for emitting radiation; primary switching means for selectively energizing the relay to maintain the relay contacts in the closed state; and secondary switching means, including semiconductor means responsive to said emission of radiation from said LED means, for maintaining a conducting condition to energize the relay in parallel with said primary switching means, and for ceasing conducting each time said LED means ceases emitting radiation to cease energizing the relay and open the relay contacts the next time the load current drops below said predetermined level following the opening of said primary switching means.
Claim 20
Dependent Claim
23 words
The switching system of claim 17 in which said diode means includes first and second diodes connected in parallel and with reverse polarity.
Claim 21
Dependent Claim
23 words
The switching system of claim 17 in which said LED means includes first and second LEDs connected in parallel and with reverse polarity.
Claim 22
Dependent Claim
20 words
The switching system of claim 17 in which said LED means and said semiconductor means are included in an optocoupler.
Claim 23
Dependent Claim
23 words
The switching system of claim 17 further including resistance means connected to said semiconductor means for limiting the current through said semiconductor means.
Claim 24
Dependent Claim
16 words
The switching system of claim 17 in which said primary switching means includes a mechanical switch.
Claim 25
Dependent Claim
17 words
The switching system of claim 17 in which said primary switching means includes a solid state switch.
Claim 26
Dependent Claim
47 words
The switching system of claim 17 in which said secondary switching means switches repeatedly from said conducting condition to said non-conducting condition at a rate which equals twice the frequency of the load current so that the relay contacts are always ready for virtually instantaneous zero-current switching.
Claim 27
Dependent Claim
134 words
A zero-current a.c. switching system for controlling actuation of relay contacts between a power supply and a load comprising: means for inducing an output signal representative of the load current; means, responsive to said means for inducing, for providing an actuating signal in response to said load current dropping below a predetermined level; primary switching means for selectively energizing the relay to maintain the relay contacts in the closed state; and secondary switching means, responsive to said actuating signal, for maintaining a conducting condition to energize the relay in parallel with said primary switching means, and for ceasing conducting each time said actuating signal is ceased to de-energize the relay and open the relay contacts the next time the load current drops below said predetermined level following the opening of said primary switching means.
Claim 28
Dependent Claim
134 words
A zero-current a.c. switching system for controlling actuation of relay contacts between a power supply and a load comprising: means for inducing an output signal representative of the load current; means, responsive to said means for inducing, for providing an actuating signal in response to said load current dropping below a predetermined level; primary switching means for selectively energizing the relay to maintain the relay contacts in the closed state; and secondary switching means, responsive to said actuating signal, for maintaining a conducting condition to energize the relay in parallel with said primary switching means, and for ceasing conducting each time said actuating signal is ceased to de-energize the relay and open the relay contacts the next time the load current drops below said predetermined level following the opening of said primary switching means.
Claim 29
Dependent Claim
18 words
The switching system of claim 25 in which said means for providing said actuating signal includes amplifier means.
Claim 30
Dependent Claim
39 words
The switching means of claim 25 further including impedance means connected to said secondary switching means for controlling the current conducted through said secondary switching means in the conducting condition and for controlling the duration of the zero-current cross-over.
Claim 31
Dependent Claim
15 words
The switching system of claim 25 in which said secondary switching means includes semiconductor means.
Claim 32
Dependent Claim
16 words
The switching system of claim 25 in which said primary switching means includes a mechanical switch.
Claim 33
Dependent Claim
17 words
The switching system of claim 25 in which said primary switching means includes a solid state switch.
Claim 34
Dependent Claim
47 words
The switching system of claim 25 in which said secondary switching means switches repeatedly from said conducting condition to said non-conducting condition at a rate which equals twice the frequency of the load current so that the relay contacts are always ready for virtually instantaneous zero-current switching.
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) | 1990-06-01 | 1990-12-01 | 1991-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-01 | 1994-12-01 | 1995-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-01 | 1998-12-01 | 1999-06-02 | $7700.00 | Window Closed / Lapsed |