Patent US3754163A successfully refreshed from Google Patents.
US3754163A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protection of transformers
Assignee: Individual
•
Filing: 1972-09-21
•
Granted: 1973-08-21
•
Expires: 1992-09-21
Abstract
Abstract A system for the protection of electrical power transformers in the event of a fault occurring in which measurements of both the differential current and the voltage at the terminals of one of the windings of the transformer are utilised to provide a tripping signal to disconnect the transformer in the event of a fault occurring. The system distinguishes between a fault and a magnetising inrush situation by detecting saturation of the transformer core and operates faster than protective devices utilising a measurement of differential current only.
Inventors
- 👤 J Sykes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:23
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/04; H02H7/045
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
218 words
A system for protecting transformers against faults consisting of means for measuring the current in each of the windings of the transformer, means for comparing the currents so measured to obtain a measure of the differential current, means for measuring the voltage at the terminals of one winding of the transformer, means for estimating, from the measured values of the currents in the windings, the value of the voltage at the terminals of the said one winding of the transformer, means for determining the magnitude of the difference between the said measured voltage and the said estimated voltage, means for comparing the magnitude of said voltage difference with a reference value and for producing an output indicative of whether the magnitude of said difference is less than or greater than the reference value, means for comparing the magnitude of said differential current with a reference value and for producing an output indicative of whether the magnitude of said differential current is less than or greater than the reference value, means for combining the outputs of the two last mentioned means constructed and arranged to produce a signal that can be used to disconnect the transformer in the event that both the magnitude of the differential current and of the said voltage difference exceed the respective reference values simultaneously.
Claim 2
Independent Claim
218 words
A system for protecting transformers against faults consisting of means for measuring the current in each of the windings of the transformer, means for comparing the currents so measured to obtain a measure of the differential current, means for measuring the voltage at the terminals of one winding of the transformer, means for estimating, from the measured values of the currents in the windings, the value of the voltage at the terminals of the said one winding of the transformer, means for determining the magnitude of the difference between the said measured voltage and the said estimated voltage, means for comparing the magnitude of said voltage difference with a reference value and for producing an output indicative of whether the magnitude of said difference is less than or greater than the reference value, means for comparing the magnitude of said differential current with a reference value and for producing an output indicative of whether the magnitude of said differential current is less than or greater than the reference value, means for combining the outputs of the two last mentioned means constructed and arranged to produce a signal that can be used to disconnect the transformer in the event that both the magnitude of the differential current and of the said voltage difference exceed the respective reference values simultaneously.
Claim 3
Dependent Claim
44 words
A system as claimed in claim 1 wherein the means for estimating the value of the voltage at the terminals of the said one winding is constructed and arranged to make such estimate on the basis that the core of the transformer is saturated.
Claim 4
Dependent Claim
32 words
A system as claimed in claim 1 including means to produce a reference value with which the said voltage difference is compared said voltage difference being a function of the differential current.
Claim 5
Dependent Claim
65 words
A system as claimed in claim 1 wherein the means for estimating the value of the voltage at the terminals of the said one winding of the transformer include circuit elements producing voltages representative of the magnitudes of the self inductance of the said one winding and of the mutual inductance of the transformer respectively, the voltages thus produced being functions of the differential current.
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) | 1976-08-20 | 1977-02-19 | 1977-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-20 | 1981-02-19 | 1981-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-20 | 1985-02-19 | 1985-08-21 | $7700.00 | Window Closed / Lapsed |