Patent US4377835A successfully refreshed from Google Patents.
US4377835A
Expired / Lapsed
US
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Recovery protection device for a thyristor valve
Assignee: ABB Norden Holding AB
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Filing: 1981-06-29
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Granted: 1983-03-22
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Expires: 2001-06-29
Abstract
Abstract In a thyristor valve having a plurality of series-connected thyristors, each thyristor has an individual recovery protection device arranged in its entirety at the potential of the thyristor. For each thyristor, the protection device comprises a voltage-sensing member whch indicates the point of time when the thyristor takes up reverse blocking voltage. A time-determining member defines a certain time interval, counting from said point of time. Control members are arranged to deliver a control pulse for firing the thyristor if the off-state voltage of the thyristor during the time interval exceeds a predetermined value.
Inventors
- 👤 Gunnar Asplund
- 👤 Lars Eklund
- 👤 Bernt stlund
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:44
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0824; H02; H02H; H02H7/00; H02H7/10; H02H7/12; H02H7/125; H02H7/127
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
206 words
In a thyristor valve having a plurality of series-connected thyristors, an individual recovery protection device for each of said thyristors operating at the potential of a respective thyristor, comprising: a first voltage sensor for providing a first signal when the reverse voltage across said thyristor exceeds a first reference level; a second voltage sensor for providing a second signal when the off state voltage across said thyristor exceeds a second reference level; a bi-stable circuit having a set input connected to receive said first signal, and a reset input; a monostable circuit connected to receive an input signal from said bi-stable circuit, whereby an output pulse of fixed duration is produced; an AND circuit having a first input connected to receive said monostable circuit output pulse, and a second input connected to receive a signal from said second voltage sensor; an OR circuit having a first input connected to receive an output signal from said AND circuit, and a second input for receiving an input signal for simultaneously igniting the thyristors of said valve; said OR circuit providing an output signal to said bi-stable circuit reset input; and means for generating a control signal for igniting said thyristor in response to said OR circuit output signal.
Claim 2
Dependent Claim
206 words
In a thyristor valve having a plurality of series-connected thyristors, an individual recovery protection device for each of said thyristors operating at the potential of a respective thyristor, comprising: a first voltage sensor for providing a first signal when the reverse voltage across said thyristor exceeds a first reference level; a second voltage sensor for providing a second signal when the off state voltage across said thyristor exceeds a second reference level; a bi-stable circuit having a set input connected to receive said first signal, and a reset input; a monostable circuit connected to receive an input signal from said bi-stable circuit, whereby an output pulse of fixed duration is produced; an AND circuit having a first input connected to receive said monostable circuit output pulse, and a second input connected to receive a signal from said second voltage sensor; an OR circuit having a first input connected to receive an output signal from said AND circuit, and a second input for receiving an input signal for simultaneously igniting the thyristors of said valve; said OR circuit providing an output signal to said bi-stable circuit reset input; and means for generating a control signal for igniting said thyristor in response to said OR circuit output signal.
Claim 3
Dependent Claim
41 words
The recover protection device according to claim 1, further comprising: a third voltage sensor for generating an ignition signal when said thyristor off-state voltage exceeds a predetermined value, said ignition signal being connected to a third input of said OR circuit.
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) | 1986-03-21 | 1986-09-20 | 1987-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-03-21 | 1990-09-20 | 1991-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-03-21 | 1994-09-20 | 1995-03-22 | $7700.00 | Window Closed / Lapsed |