US4228477A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for monitoring the current distribution in parallel-connected converted branches
Assignee: Siemens AG
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Filing: 1979-01-31
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Granted: 1980-10-14
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Expires: 1999-01-31
Abstract
Abstract A circuit arrangement for monitoring the current inbalance in two parallel-connected converter branches, each of which includes at least two series-connected converter valves. The anodes and cathodes, respectively, of adjacent converter valves in a given branch are connected together via cross-connections containing current transformers. A differential current transformer is provided at the output junction point of the two converter branches. Starting with the output signal of the differential current transformer, the exact current misdistribution for each adjacent converter valve pair is determined via summing amplifiers by adding the currents of the transverse transformers. A protective measure is triggered if a current misdistribution occurs.
Inventors
- 👤 Achim Claus
- 👤 Heinrick Geissing
- 👤 Willi Ulbrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:16
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/10; H02H7/12; G; G01; G01R; G01R19/00; G01R19/10; H02H3/00; H02H3/26; H02H3/36
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
168 words
A circuit arrangement for monitoring current in two parallel-connected converter branches each of which comprises at least two series-connected converter valves comprising: a differential current transformer for measuring the difference between the levels of currents flowing in the two branches at a junction point of the branches, cross-connections, each containing the primary winding of a current transformer, for connecting the anodes and cathodes of corresponding converter valves in both branches, and threshold detection means associated with each transformer for triggering protective measures in response to current imbalance comprising an amplifier connected to the output of the differential current transformer for supplying a signal to a threshold detector and a summing amplifier in each cross-connection for supplying a signal to a threshold detector, the summing amplifier having one summing input connected to the current transformer and another summing input connected to the output of the respective preceding amplifier, the gains of the circuits containing the amplifier and the summing amplifiers being in the ratio of 0.5 to 1, respectively.
Claim 2
Dependent Claim
168 words
A circuit arrangement for monitoring current in two parallel-connected converter branches each of which comprises at least two series-connected converter valves comprising: a differential current transformer for measuring the difference between the levels of currents flowing in the two branches at a junction point of the branches, cross-connections, each containing the primary winding of a current transformer, for connecting the anodes and cathodes of corresponding converter valves in both branches, and threshold detection means associated with each transformer for triggering protective measures in response to current imbalance comprising an amplifier connected to the output of the differential current transformer for supplying a signal to a threshold detector and a summing amplifier in each cross-connection for supplying a signal to a threshold detector, the summing amplifier having one summing input connected to the current transformer and another summing input connected to the output of the respective preceding amplifier, the gains of the circuits containing the amplifier and the summing amplifiers being in the ratio of 0.5 to 1, respectively.
Claim 3
Dependent Claim
22 words
A circuit arrangement in accordance with claim 1 in which the differential current transformer and the current transformers comprise bushing current transformers.
Claim 4
Dependent Claim
38 words
A circuit arrangement in accordance with claim 2 in which the line sections located immediately ahead of the junction point of both converter branches are brought through the measuring openings of the differential current transformer in opposite directions.
Claim 5
Dependent Claim
19 words
A circuit arrangement in accordance with claim 1 in which the amplifier and the summing amplifiers comprise operational amplifiers.
Claim 6
Dependent Claim
27 words
A circuit arrangement in accordance with claim 1 in which each threshold detection means includes an absolute value former connected between the amplifier and the threshold detection.
Claim 7
Dependent Claim
38 words
A circuit arrangement in accordance with claim 1 in which the output signal of the amplifier or one of the summing amplifiers is fed to a first threshold detector and, via an inverter, to a second threshold detector.
Claim 8
Dependent Claim
33 words
A circuit arrangement in accordance with claim 1, further comprising the threshold members being operational amplifiers having a uniform DC voltage applied to the noninverting inputs of the amplifiers as the threshold value.
Claim 9
Dependent Claim
27 words
A circuit arrangement in accordance with claim 1 in which the protective measure triggered by a threshold detector is disconnection of both converter branches by a switch.
Claim 10
Dependent Claim
33 words
A circuit arrangement in accordance with claim 1 wherein the converter is self-commutating and the protective measure comprises the controlled converter valves of both converter branches being quenched when a threshold detector responds.
Claim 11
Dependent Claim
27 words
A circuit arrangement in accordance with any one of claims 1 to 9, further comprising the protective measure being triggered by relays connected to the threshold detectors.
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) | 1983-10-14 | 1984-04-14 | 1984-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-14 | 1988-04-14 | 1988-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-14 | 1992-04-14 | 1992-10-14 | $7700.00 | Window Closed / Lapsed |