US3790846A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic load monitoring and transfer circuit
Assignee: Individual
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Filing: 1972-12-18
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Granted: 1974-02-05
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Expires: 1992-12-18
Abstract
Abstract Primary and standby loads are connected in parallel with a source of AC power. Primary and standby bidirectional thyristors are connected in series with the primary and standby loads respectively. Gate control circuits for the bidirectional thyristors are coupled together in such a manner that as one of the gate control circuits is energized it shunts current from the other to provide a bistable mode of operation. A phase shifter is provided for advancing the phase of the gate current to the primary thyristor relative to the phase of the gate current to the standby thyristor to initiate operation of the primary load. Upon an open circuit failure of the primary load, operation automatically switches to the standby load. The entire load monitoring and transfer circuit is conveniently housed in a twin lamp light socket. An indicator light is provided for indicating that the standby load is in operation or that the standby load is good as held in reserve.
Inventors
- 👤 M Morris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:23
CPC Classifications
H; H05; H05B; H05B39/00; H05B39/10; H05B39/105
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
205 words
In an automatic load monitoring and transfer circuit: means for connecting primary and standby loads in parallel with each other and for connecting said primary and standby loads across a source of AC power; primary and standby bidirectional thyristors connected in series with said primary and standby load connecting means respectively to define with said load connecting means primary and standby parallel circuit branches; primary and standby gate control circuits for controlling electrical conduction through said respective primary and standby bidirectional thyristors; means interconnecting said primary and standby gate control circuits for shunting gate drive current from said standby gate control circuit upon firing of said primary bidirectional thyristor and for preferentially firing said standby bidirectional thyristor upon open circuit failure of said primary load; and phase shifting means connected for advancing the phase of the gate drive current to said primary bidirectional thyristor relative to the phase of the gate drive current to said standby bidirectional thyristor, whereby advanced firing of said primary bidirectional thyristor serves to gate load current through said primary load connecting means and serves to shunt gate drive current from said standby thyristor to hold said standby thyristor in the non-conductive state so long as said primary load remains conductive.
Claim 2
Dependent Claim
205 words
In an automatic load monitoring and transfer circuit: means for connecting primary and standby loads in parallel with each other and for connecting said primary and standby loads across a source of AC power; primary and standby bidirectional thyristors connected in series with said primary and standby load connecting means respectively to define with said load connecting means primary and standby parallel circuit branches; primary and standby gate control circuits for controlling electrical conduction through said respective primary and standby bidirectional thyristors; means interconnecting said primary and standby gate control circuits for shunting gate drive current from said standby gate control circuit upon firing of said primary bidirectional thyristor and for preferentially firing said standby bidirectional thyristor upon open circuit failure of said primary load; and phase shifting means connected for advancing the phase of the gate drive current to said primary bidirectional thyristor relative to the phase of the gate drive current to said standby bidirectional thyristor, whereby advanced firing of said primary bidirectional thyristor serves to gate load current through said primary load connecting means and serves to shunt gate drive current from said standby thyristor to hold said standby thyristor in the non-conductive state so long as said primary load remains conductive.
Claim 3
Dependent Claim
44 words
The apparatus of claim 1 wherein said primary and standby bidirectional thyristors each comprise triacs, and wherein said primary and standby gate control circuits include primary and gate resistor means interconnecting respective gate and terminal number ones of said respective primary and standby thyristors.
Claim 4
Dependent Claim
51 words
The apparatus of claim 2 wherein said standby resistor means of said standby gate control circuit includes a series connection of first and second resistors to define a node therebetween, and wherein said terminal number one of said primary thyristor is connected to said node of said standby gate control circuit.
Claim 5
Dependent Claim
62 words
The apparatus of claim 3 wherein the resistance of said primary gate control resistor means is approximately equal to the resistance of said first resistor means of said standby gate control resistor means, and wherein the resistance of said second resistor of said standby gate control circuit is substantially less than the resistance of said first resistor of said gate control circuit.
Claim 6
Dependent Claim
28 words
The apparatus of claim 1 wherein said phase shifting means includes, a capacitor connected between terminal number one and the gate control terminal of said primary bidirectional thyristor.
Claim 7
Dependent Claim
41 words
The apparatus of claim 1 wherein said means for connecting said primary and standby loads in parallel includes, a housing having a pair of lamp sockets formed therein to receive primary and standby incandescent lamps forming said primary and stanDby loads.
Claim 8
Dependent Claim
35 words
The apparatus of claim 1 including, primary and standby loads connected in parallel via said primary and standby load connecting means, and wherein said primary and standby loads comprise primary and standby incandescent lamps, respectively.
Claim 9
Dependent Claim
32 words
The apparatus of claim 1 including, an indicating means connected in series with said standby load and said primary bidirectional thyristor for sensing and indicating a conductive path through said standby load.
Claim 10
Dependent Claim
28 words
The apparatus of claim 1 including, an indicating means connected in parallel with said standby load for indicating conduction of load current through said standby parallel circuit branch.
Claim 11
Dependent Claim
28 words
The apparatus of claim 6 wherein said housing includes, a third lamp socket to receive an indicating lamp for indicating flow of load current through said standby lamp.
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) | 1977-02-04 | 1977-08-06 | 1978-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-04 | 1981-08-06 | 1982-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-04 | 1985-08-06 | 1986-02-05 | $7700.00 | Window Closed / Lapsed |