US3591831A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Harmonic filter protection means
Assignee: CGEE ALSTHOM NORTH AMERICA Inc
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Filing: 1969-10-23
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Granted: 1971-07-06
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Expires: 1989-10-23
Abstract
Abstract A protection system and fault indicator for harmonic filters associated with high-voltage electric power lines. Residual fundamental-frequency currents passed by two such filters connected to the same line are compared in the current circuit of a power directional relay. The system is adjusted so that under normal operating conditions the net fundamental-frequency current in the current circuit of the relay is zero. If one of the two filters malfunctions, the resulting increase in its fundamentalfrequency current actuates the relay in a sense that indicates which filter is in trouble.
Inventors
- 👤 Andrew J Mcconnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 16:12
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/26; H02H3/36; H02H7/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
117 words
In a protection system for a group of different harmonic filters comprising at least first and second parallel filters connected to a conductor carrying alternating current of fundamental frequency: a. power directional sensing means comprising separate potential and current circuits, said sensing means being operative to initiate a predetermined protective function in response to the simultaneous energization of said circuits by out-of-phase electrical quantities having like frequencies; b. first means for supplying said potential circuit with a first quantity derived from fundamental-frequency voltage across said group of filters; and c. second means for supplying said current circuit with a second quantity essentially representing any abnormal difference between fundamental-frequency currents flowing through the first and second filters, respectively.
Claim 2
Dependent Claim
117 words
In a protection system for a group of different harmonic filters comprising at least first and second parallel filters connected to a conductor carrying alternating current of fundamental frequency: a. power directional sensing means comprising separate potential and current circuits, said sensing means being operative to initiate a predetermined protective function in response to the simultaneous energization of said circuits by out-of-phase electrical quantities having like frequencies; b. first means for supplying said potential circuit with a first quantity derived from fundamental-frequency voltage across said group of filters; and c. second means for supplying said current circuit with a second quantity essentially representing any abnormal difference between fundamental-frequency currents flowing through the first and second filters, respectively.
Claim 3
Dependent Claim
28 words
The protection system of claim 1 in which said first means includes phase shifting means for obtaining a predetermined phase relationship between said first quantity and said voltage.
Claim 4
Dependent Claim
21 words
The protection system of claim 1 in which said second means includes means for restricting harmonic-frequency current in said current circuit.
Claim 5
Dependent Claim
37 words
The protection system of claim 1 in which said second means includes compensating means responsive to any normal difference between said fundamental-frequency currents for ensuring that the magnitude of said second quantity is zero during normal conditions.
Claim 6
Dependent Claim
23 words
The protection system of claim 1 which includes overvoltage responsive means connected in parallel with said current circuit for preventing excessive voltage thereacross.
Claim 7
Dependent Claim
52 words
The protection system of claim 1 in which said sensing means is constructed and arranged to initiate one protective function if said second quantity has a leading phase relation to said first quantity and to initiate another protective function if said second quantity has a lagging phase relation to said first quantity.
Claim 8
Dependent Claim
109 words
The protection system of claim 1 which includes a second power directional sensing means having a potential circuit connected in parallel with the potential circuit of the first-mentioned sensing means for energization by another electrical quantity derived from said voltage, and having a current circuit connected in series with the current circuit of said first sensing means, said second sensing means being operative in response to the simultaneous energization of its circuits for initiating one protective function when said second quantity has a leading phase relation to said other quantity and for initiating another protective function when said second quantity has a lagging phase relation to said other quantity.
Claim 9
Dependent Claim
36 words
The protection system of claim 7 in which said second sensing means is arranged to operate when said second quantity attains a magnitude lower than its threshold level at which said first sensing means is actuated.
Claim 10
Dependent Claim
23 words
The protection system of claim 7 which includes means for temporarily delaying said predetermined protective function upon actuation of said first sensing means.
Claim 11
Dependent Claim
32 words
The protection system of claim 1 in which said sensing means is arranged to operate in delayed response to the simultaneous energization of its ciRcuits by said first and second quantities, respectively.
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) | 1974-07-05 | 1975-01-04 | 1975-07-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-05 | 1979-01-04 | 1979-07-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-05 | 1983-01-04 | 1983-07-06 | $7700.00 | Window Closed / Lapsed |