US4198625A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual alarm detection on single loop
Assignee: SPX Technologies Inc
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Filing: 1978-05-02
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Granted: 1980-04-15
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Expires: 1998-05-02
Abstract
Abstract A circuit for distinguishing between two classes of alarms on a single loop. An alarm of a first class causes an impedance of a first predetermined value to be added in the loop; and an alarm of a second class causes a much larger additional impedance, or an open condition, to be inserted in the loop. The loop is bridged across an element of a voltage divider and, therefore, the loop characteristics, including the changed characteristics due to the impedance change in response to an alarm of either class, controls the potential of a test point of the voltage divider. Voltage comparators monitor the potential of the test point relative to control potentials, and cause relays to provide a no alarm signal, a first alarm signal, or a second alarm signal when there is no alarm condition on the loop, an alarm of the first class, or an alarm of the second class, respectively, on the loop.
Inventors
- 👤 Irving Mande
- 👤 Robert W. Right
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:36
CPC Classifications
G; G08; G08B; G08B19/00; G08B23/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
190 words
An alarm differentiating circuit comprising in combination: (a) a potential source having lower and upper potential limits identified herein as A and I, respectively, and intermediate potentials from B to H increasing in magnitude, with respect to A, in alphabetic sequence; (b) first circuit means bridged across said potential source for clamping first and second terminals at potentials D and G, respectively; (c) second circuit means responsive to a non-alarm indicating condition for maintaining a third terminal at a potential within the range of H to I; (d) said second circuit means responsive to a first class of alarm indication for switching said third terminal to a potential within the range of E to F; (e) said second circuit means responsive to a second class of alarm indication for switching said third terminal to a potential within the range of B to C; and (f) potential differentiating means coupled to said potential source, and said first, second and third terminals for producing first, second and third unique alarm indicating signals when said third terminal is within said H to I; E to F; and B to C potential range, respectively.
Claim 2
Dependent Claim
190 words
An alarm differentiating circuit comprising in combination: (a) a potential source having lower and upper potential limits identified herein as A and I, respectively, and intermediate potentials from B to H increasing in magnitude, with respect to A, in alphabetic sequence; (b) first circuit means bridged across said potential source for clamping first and second terminals at potentials D and G, respectively; (c) second circuit means responsive to a non-alarm indicating condition for maintaining a third terminal at a potential within the range of H to I; (d) said second circuit means responsive to a first class of alarm indication for switching said third terminal to a potential within the range of E to F; (e) said second circuit means responsive to a second class of alarm indication for switching said third terminal to a potential within the range of B to C; and (f) potential differentiating means coupled to said potential source, and said first, second and third terminals for producing first, second and third unique alarm indicating signals when said third terminal is within said H to I; E to F; and B to C potential range, respectively.
Claim 3
Dependent Claim
86 words
The combination as set forth in claim 1, wherein said potential differentiating means comprises four voltage comparators, (a) with a first one of said comparators sensing the relative potential between potential G and said third terminal; (b) with a second one of said voltage comparators sensing the relative potential between potential D and said third terminal; and (c) with the third and fourth ones of said voltage comparators sensing the relative potential between potential D and the output of said second one of said voltage comparators.
Claim 4
Dependent Claim
22 words
The combination as set forth in claim 2, wherein said third and fourth voltage comparators produce inverse outputs relative to each other.
Claim 5
Dependent Claim
21 words
The combination as set forth in claim 3, wherein the outputs of said first and third voltage comparators are coupled together.
Claim 6
Dependent Claim
82 words
The combination as set forth in claim 4 and including first and second sensing circuits, each having first and second stable states, coupled to the outputs of said third and fourth voltage comparators, respectively, for producing one of three unique output signals indicative of the outputs of said third and fourth voltage comparators which, in turn, are indicative of the specific one of the potential H to I; E to F and B to C within which said third terminal may reside.
Claim 7
Dependent Claim
40 words
The combination as set forth in claim 5, wherein said first and second sensing circuits are both in a first one of their first and second stable states when said third terminal is in the potential range H to I.
Claim 8
Dependent Claim
38 words
The combination as set forth in claim 5 or 6, wherein said first and second sensing circuits are in said second and first stable states, respectively, when said third terminal is in the potential range E to F.
Claim 9
Dependent Claim
36 words
The combination as set forth in claim 7, wherein said first and second sensing circuits are in said first and second stable states, respectively, when said third terminal is in the potential range B to C.
Claim 10
Dependent Claim
45 words
The combination as set forth in claim 5, wherein one of said first and second sensing circuits is electrically lockable and locks into one of its stable states when triggered to that state and independent of the continuation of the condition which initiated the action.
Claim 11
Dependent Claim
34 words
The combination as set forth in claim 9, wherein said lockable sensing circuit locks in response to said third terminal declining from the potential range H to I, to the range E to F.
Claim 12
Dependent Claim
43 words
The combination as set forth in claim 10, wherein said lockable sensing circuit does not lock in response to said third terminal declining from the potential range to H to I through said range E to F to the range B to C.
Claim 13
Dependent Claim
16 words
The combination as set forth in claim 11, wherein said lockable sensing circuit includes a relay.
Claim 14
Dependent Claim
67 words
The combination as set forth in claim 1, wherein said second circuit means comprises, (a) a voltage divider bridged across said potential source and wherein a junction point of said voltage divider comprises said third terminal; and (b) a loop bridged across an element of said voltage divider for modifying the potential of said third terminal in response to a change in the impedance of said loop.
Claim 15
Dependent Claim
50 words
The combination as set forth in claim 13, wherein said loop includes first and second classes of normally closed series connected contacts for modifying the impedance of said loop in first and second manners in response to the opening of one of said first and second classes of contacts, respectively.
Claim 16
Dependent Claim
28 words
The combination as set forth in claim 14, wherein said first and second classes of series contacts modify the impedance of said loop by increasing the loop impedance.
Claim 17
Dependent Claim
22 words
The combination as set forth in claim 15, wherein a contact of said first class unshunts a first fixed impedance when opened.
Claim 18
Dependent Claim
24 words
The combination as set forth in claim 15 or 16, wherein a contact of said second class unshunts a second fixed impedance when opened.
Claim 19
Dependent Claim
28 words
The combination as set forth in claim 15 or 16, wherein the electrical continuity of said loop is broken in response to contacts of said second class opening.
References Cited (Backward Citations)
US3646552A
Cited
US3702474A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |