US3553531A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Voltage stabilizer with overload protection and automatic restoration
Assignee: Italtel SpA
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Filing: 1969-05-08
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Granted: 1971-01-05
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Expires: 1989-05-08
Abstract
Abstract The voltage developed across a partly capacitive load L is stabilized by a transistor Ts1, connected in series with the load, which has a feedback loop including an amplifier A receiving the output of a comparator S matching the load voltage against a fixed reference voltage. Upon cut-in, the feedback amplifier and the series transistor are blocked and a bypass G supplies a trickle current Ig which, as the load voltage Vu builds up to a relatively low first level V4, unblocks the series transistor via a threshold network S4 whereupon normal load current begins to flow and, as the load voltage reaches a higher second level V2, the feedback amplifier is activated through another threshold network S2 to initiate voltage regulation. If, on overload or short circuit, the load voltage temporarily drops below its normal level V1, a current-limiting network S1 blocks the series transistor; a sustained voltage reduction below the second level V2 deactivates the feedback amplifier, resumption of normal operation with removal of the overload being delayed by a storage circuit M having a time constant greater than that of the load. A further threshold network S3 disconnects the bypass under normal operating conditions.
Inventors
- 👤 Augusto Rimondini
- 👤 Primo Foresti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:11
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/56; G05F1/565; G05F1/569; G05F1/573; G05F1/5735
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
207 words
A voltage stabilizer comprising: an input circuit connectable across a source of operating voltage; an output circuit containing a load; dynamic resistance means connected in series between said input and output circuits and provided with feedback means responsive to an output voltage developed across said load for varying the magnitude of said dynamic resistance means in a sense tending to hold said output voltage substantially constant at a normal operating level; blocking means connected to said output circuit for deactivating said feedback means and cutting off current flow through said dynamic resistance means in response to said output voltage dropping to a predetermined first level below said operating level; starting means connected to said output circuit for restoring current flow through said dynamic resistance means in response to said output voltage rising to a predetermined second level below said first level while maintaining said feedback means inactive until attainment of said first level; delay means controlled by said blocking means for maintaining said starting means inoperative for a predetermined period following cutoff of current flow through said dynamic resistance means; and current-limiting means coupled to said dynamic resistance means for holding the conductivity thereof substantially constant in response to said current flow reaching a maximum rated value.
Claim 2
Dependent Claim
207 words
A voltage stabilizer comprising: an input circuit connectable across a source of operating voltage; an output circuit containing a load; dynamic resistance means connected in series between said input and output circuits and provided with feedback means responsive to an output voltage developed across said load for varying the magnitude of said dynamic resistance means in a sense tending to hold said output voltage substantially constant at a normal operating level; blocking means connected to said output circuit for deactivating said feedback means and cutting off current flow through said dynamic resistance means in response to said output voltage dropping to a predetermined first level below said operating level; starting means connected to said output circuit for restoring current flow through said dynamic resistance means in response to said output voltage rising to a predetermined second level below said first level while maintaining said feedback means inactive until attainment of said first level; delay means controlled by said blocking means for maintaining said starting means inoperative for a predetermined period following cutoff of current flow through said dynamic resistance means; and current-limiting means coupled to said dynamic resistance means for holding the conductivity thereof substantially constant in response to said current flow reaching a maximum rated value.
Claim 3
Dependent Claim
55 words
A voltage stabilizer as defined in claim 1, further comprising generator means responsive to said operating voltage for passing a trickle current through said load in the cutoff condition of said dynamic resistance means, thereby developing across said load an output voltage rising to said second level in the presence of a finite load resistance.
Claim 4
Dependent Claim
24 words
A voltage stabilizer as defined in claim 2 wherein said generator means comprises a high-resistance bypass path in shunt with said dynamic resistance means.
Claim 5
Dependent Claim
31 words
A voltage stabilizer as defined in claim 3 wherein said bypass path includes electronic switch means responsive to an output voltage higher than said second level for interrupting said trickle current.
Claim 6
Dependent Claim
55 words
A voltage stabilizer as defined in claim 1 wherein said delay means comprises a storage condenser connected to be charged by said output voltage in the active conditions of said feedback means, said condenser being provided with a charging circuit of relatively low time constant and with a discharging circuit of relatively high time constant.
Claim 7
Dependent Claim
29 words
A voltage stabilizer as defined in claim 5 wherein said load is partly reactive, said relatively high time constant being greater than the maximum time constant of said load.
Claim 8
Dependent Claim
60 words
A voltage stabilizer as defined in claim 5 wherein said feedback means comprises an amplifier with a control electrode connected to said output circuit for energization by said output voltage, said blocking means including a Zener diode inserted between said control electrode and said output circuit, said charging circuit being connected to said Zener diode in parallel with said amplifier.
Claim 9
Dependent Claim
46 words
A voltage stabilizer as defined in claim 7 where said starting means comprises a first transistor without input means connected across said condenser, said dynamic resistance means comprising a second transistor with parallel input connections to the outputs of said amplifier and of said first transistor.
Claim 10
Dependent Claim
25 words
A voltage stabilizer as defined in claim 8 wherein said current-limiting means comprises a further Zener diode connected across the input of said second transistor.
Claim 11
Dependent Claim
62 words
A voltage stabiliZer as defined in claim 7 wherein said feedback means further comprises a voltage divider connected across said output circuit, a source of reference voltage, and comparison means with two inputs respectively connected to a tap on said voltage divider and to said source of reference voltage, said comparison means having an output connected to an input of said amplifier.
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) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |