US4991049A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Anti-short-cycle circuit
Assignee: International Controls and Measurements Corp
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Filing: 1989-10-12
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Granted: 1991-02-05
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Expires: 2009-10-12
Abstract
Abstract A protective time delay delay circuit delays energization to an electric load until a predetermined time has elapsed from a previous deenergization. A transistor has its emitter connected to an ac conductor and has its base coupled to an RC timing circuit. The collector is connected to the gate of a triac whose current electrodes are coupled to the thermostat conductor and to a load device. A small resistor and a zener can be connected to the transistor to provide brownout protection. A temperature sensitive resistor can be included to increase or decrease the lockout period as a function of temperature. This resistor can be remotely mounted in thermal proximity to the load to be protected. A thermistor placed in parallel to latching capacitor can provide thermal overload protection.
Inventors
- 👤 Andrew S. Kadah
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 02:59
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/0816
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
119 words
Protective circuit for delaying energization of a load when a voltage is applied until a predetermined time period has elapsed following a previous de-energization, comprising a triac having a first power electrode connected to a first ac conductor, a second power electrode connected to a load device which is in turn connected to a second ac conductor, and a gate electrode; a transistor having a base, electrode, an emitter electrode coupled to said first ac conductor, and a collector electrode connected to the gate of said triac; a latching capacitor connected between the gate of said triac and said second ac conductor; and a capacitor timing circuit coupled between the base of said transistor and said second ac conductor.
Claim 2
Dependent Claim
119 words
Protective circuit for delaying energization of a load when a voltage is applied until a predetermined time period has elapsed following a previous de-energization, comprising a triac having a first power electrode connected to a first ac conductor, a second power electrode connected to a load device which is in turn connected to a second ac conductor, and a gate electrode; a transistor having a base, electrode, an emitter electrode coupled to said first ac conductor, and a collector electrode connected to the gate of said triac; a latching capacitor connected between the gate of said triac and said second ac conductor; and a capacitor timing circuit coupled between the base of said transistor and said second ac conductor.
Claim 3
Dependent Claim
22 words
Protective circuit as in claim 1 further comprising a rectifying diode in series between said emitter electrode and said first ac conductor.
Claim 4
Dependent Claim
16 words
Protective circuit as in claim 2 further comprising a resistance in series with said rectifying diode.
Claim 5
Dependent Claim
18 words
Protective circuit as in claim 3 wherein said resistance has a value of about 10 to 1000 ohms.
Claim 6
Dependent Claim
23 words
Protective circuit as in claim 3 further comprising a zener diode connected in series between said emitter electrode and said first ac conductor.
Claim 7
Dependent Claim
27 words
Protective circuit as in claim 1 wherein said capacitive timing circuit consists of a capacitor connected between the base of said transistor and said second ac conductor.
Claim 8
Dependent Claim
48 words
Protective circuit as in claim 1 wherein said capacitive timing circuit includes a timing capacitor connected to the base of said transistor and to said second ac conductor, and a timing resistor connected to said base and to said second ac conductor in parallel with said timing capacitor.
Claim 9
Dependent Claim
26 words
Protective circuit as in claim 7 wherein said timing capacitor and timing resistor have a time constant on the order of about three to ten seconds.
Claim 10
Dependent Claim
20 words
Protective circuit as in claim 7 further including a current-limiting resistor in series with said base and said timing capacitor.
Claim 11
Dependent Claim
26 words
Protective circuit as in claim 7 wherein said timing resistor has a temperature-dependent value to provide a time constant that adjusts automatically to severe temperature conditions.
Claim 12
Dependent Claim
25 words
Protective circuit as in claim 1 further comprising a temperature sensitive resistance in parallel with said latching capacitor to provide temperature-actuated shut-off for said triac.
Claim 13
Dependent Claim
33 words
Protective circuit as in claim 1 further comprising a transient protective capacitor connected between said first and second ac conductors in parallel with a circuit formed of said triac and said load device.
Claim 14
Dependent Claim
21 words
Protective circuit as in claim 1 wherein said first 2 and second ac conductors carry 24 volt ac thermostat control power.
Claim 15
Dependent Claim
20 words
Protective circuit as in claim 1 wherein said first and second ac conductors carry from 3 vac to 460 vac.
Claim 16
Dependent Claim
25 words
Protective circuit as in-claim 7 wherein said timing capacitor and timing resistor have a time constant on the order of 0.1 seconds to ten minutes.
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) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |