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US3819956A
Expired / Lapsed
US
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Lockout means for thyristor firing circuit
Assignee: Schneider Electric USA Inc
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Filing: 1972-07-20
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Granted: 1974-06-25
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Expires: 1992-07-20
Abstract
Abstract A thyristor firing circuit uses saturable transformers to transmit firing pulses to the thyristors. A lockout circuit causes a constant voltage to be applied to the transformer primaries to saturate the transformers so that neither circuit noise nor transients can produce firing pulses in the secondary windings.
Inventors
- 👤 R Hughes
- 👤 M Messick
- 👤 J Volpe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:39
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/16; H03K17/51; H03K17/56; H03K17/72
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
A thyristor firing circuit comprising: a direct current source, a saturable transformer having a primary and a secondary winding, switching means having a pair of inputs connected to a pulsating signal source and a pair of outputs connected between the primary winding and the direct current source for supplying pulses of direct current to the primary windinG in response to the input signal pulses for causing the secondary winding to produce output thyristor firing pulses, and lockout firing means having an output for causing the switching means to conduct continuously for causing a continuous direct current flow in the primary winding to saturate the saturable transformer to prevent the secondary winding from producing output thyristor firing pulses in response to the input signal pulses.
Claim 2
Dependent Claim
124 words
A thyristor firing circuit comprising: a direct current source, a saturable transformer having a primary and a secondary winding, switching means having a pair of inputs connected to a pulsating signal source and a pair of outputs connected between the primary winding and the direct current source for supplying pulses of direct current to the primary windinG in response to the input signal pulses for causing the secondary winding to produce output thyristor firing pulses, and lockout firing means having an output for causing the switching means to conduct continuously for causing a continuous direct current flow in the primary winding to saturate the saturable transformer to prevent the secondary winding from producing output thyristor firing pulses in response to the input signal pulses.
Claim 3
Dependent Claim
36 words
The firing circuit as recited in claim 1 wherein the switching means includes a transistor having an emitter and collector connected in series with the primary winding and a base connected to the pulsating signal source.
Claim 4
Dependent Claim
23 words
The firing circuit as recited in claim 2 wherein the output of the lockout means is applied to the base of the transistor.
Claim 5
Dependent Claim
21 words
The firing circuit as recited in claim 3 wherein the output of the lockout means causes the transistor to be conductive.
Claim 6
Dependent Claim
57 words
The firing circuit as recited in claim 1 wherein the pulsating signal source causes the switching means to repeatedly switch between a conducting and non-conducting condition and the lockout means includes means for applying a continuous signal to the switching means to maintain the switching means in its conducting condition thereby causing saturation of the saturable transformer.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |