Patent US3909672A successfully refreshed from Google Patents.
US3909672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitor bank protection relay
Assignee: ABB Inc USA
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Filing: 1974-02-07
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Granted: 1975-09-30
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Expires: 1994-02-07
Abstract
Abstract A protective relay for shunt capacitor banks which is arranged to provide a neutralizing signal which balances any initial unbalance inherent in the capacitor bank which may be due to slight differences in the capacitors which make up the bank so that initially the output signal is substantially zero whereby the sensitivity of the relay to the failure of one or more of the parallel series connected capacitors is considerably increased without the necessity of amplification or other complications. The relay further is rendered insensitive to varying unbalances present in the polyphase transmission line, not caused by capacitor failure, by the use of resistive elements connected to compensate for line unbalance. These resistors will be more secure against failure than the capacitor elements used in the shunt capacitor banks.
Inventors
- 👤 Thomas G Lundquist
- 👤 Victor Burtnyk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 17:35
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/16
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
200 words
A protective relay for protecting a polyphase shunt capacitor bank energized from a polyphase power transmission line in which said bank includes a plurality of arrays of interconnected capacitors, said relay comprising, a first circuit means operatively connected to said polyphase capacitor bank and sensing the magnitude of the current through each of said capacitor arrays established as a consequence of the operation of said capacitor bank, said first means having an output circuit energized with a first output quantity having a magnitude which is a function of the change in relative operating condition of said capacitor arrays, a second circuit means consisting solely of substantially resistive Elements operatively connected to said polyphase line and sensing the magnitude of a desired electrical component established as a consequence of the opertion of said transmission line, the magnitude of said second output quantity being a function of the magnitude of the voltage relations between the conductors said polyphase line, and third circuit means operatively connected to said output circuits of said first and second circuit means, said third circuit means having an output circuit energized in response to a change in the relative in magnitudes of said first and second output quantities.
Claim 2
Dependent Claim
200 words
A protective relay for protecting a polyphase shunt capacitor bank energized from a polyphase power transmission line in which said bank includes a plurality of arrays of interconnected capacitors, said relay comprising, a first circuit means operatively connected to said polyphase capacitor bank and sensing the magnitude of the current through each of said capacitor arrays established as a consequence of the operation of said capacitor bank, said first means having an output circuit energized with a first output quantity having a magnitude which is a function of the change in relative operating condition of said capacitor arrays, a second circuit means consisting solely of substantially resistive Elements operatively connected to said polyphase line and sensing the magnitude of a desired electrical component established as a consequence of the opertion of said transmission line, the magnitude of said second output quantity being a function of the magnitude of the voltage relations between the conductors said polyphase line, and third circuit means operatively connected to said output circuits of said first and second circuit means, said third circuit means having an output circuit energized in response to a change in the relative in magnitudes of said first and second output quantities.
Claim 3
Dependent Claim
28 words
The relay of claim 1 in which said resistive elements are connected together in the same polyphase configuration as are the arrays of capacitors of said capacitor bank.
Claim 4
Dependent Claim
25 words
The relay of claim 2 in which said resistive elements and said arrays of said capacitors of said bank are both connected in delta configuration.
Claim 5
Dependent Claim
50 words
The relay of claim 1 in which said resistive elements and said capacitor arrays are connected in wye configuration and in which said first and second output quantities are determined as a function of the magnitudes of said components between the neutral of the respective said wye configurations and ground.
Claim 6
Dependent Claim
23 words
The relay of claim 4 in which each of said first and second circuit means individually includes the winding of an individual transformer.
Claim 7
Dependent Claim
23 words
The relay of claim 5 in which said windings of said transformers are of high impedance and said output quantities are voltage quantities.
Claim 8
Dependent Claim
183 words
A protective relay for protecting a polyphase shunt capacitor bank energized from a polyphase power transmission line, said relay comprising, a first circuit means operatively connected to said capacitor bank and operable to sense the magnitude of the unbalance in a desired electrical quantity present in said capacitor bank, a second circuit means consisting solely of substantially resistive elements operatively connected to said polyphase line and operable to sense the unbalanced magnitude of said desired electrical quantity present in said line independently of the magnitude of the unbalance of said quantity caused by the operation of said capacitor bank, and third circuit means interconnecting said first and second circuit means and effective to provide a desired output signal when the magnitude of unbalance of said quantities sensed thereby reaches a predetermined established magnitude, and adjustable means altering the effect of the relative magnitude of unbalance of said quantity sensed by said second circuit means to compensate for any initial inherent unbalance of said quantity present in said capacitor bank whereby the initial relative magnitude with unfaulted capacitors in said bank is substantially zero.
Claim 9
Dependent Claim
183 words
A protective relay for protecting a polyphase shunt capacitor bank energized from a polyphase power transmission line, said relay comprising, a first circuit means operatively connected to said capacitor bank and operable to sense the magnitude of the unbalance in a desired electrical quantity present in said capacitor bank, a second circuit means consisting solely of substantially resistive elements operatively connected to said polyphase line and operable to sense the unbalanced magnitude of said desired electrical quantity present in said line independently of the magnitude of the unbalance of said quantity caused by the operation of said capacitor bank, and third circuit means interconnecting said first and second circuit means and effective to provide a desired output signal when the magnitude of unbalance of said quantities sensed thereby reaches a predetermined established magnitude, and adjustable means altering the effect of the relative magnitude of unbalance of said quantity sensed by said second circuit means to compensate for any initial inherent unbalance of said quantity present in said capacitor bank whereby the initial relative magnitude with unfaulted capacitors in said bank is substantially zero.
Claim 10
Dependent Claim
29 words
The relay of claim 7 in which the capacitors of said capacitor bank are connected in the same array as are the resistive elements of said second circuit means.
Claim 11
Dependent Claim
17 words
The relay of claim 8 in which said capacitors and said resistive elements are connected in wye.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |