Electricity: electrical systems and devices – Safety and protection of systems and devices – Transformer protection
Patent
1989-02-01
1991-05-07
Jennings, Derek S.
Electricity: electrical systems and devices
Safety and protection of systems and devices
Transformer protection
361 93, H02H 7045
Patent
active
050141538
ABSTRACT:
An apparatus for monitoring phased currents in a first winding and a second winding of a transformer and for disconnecting the transformer from a power source supplying the transformer when a difference between the magnitude of the current in the first winding and the magnitude of the current in the second winding exceeds a predetermined amount to indicate a fault condition is disclosed. The apparatus is used in combination with circuitry for generating first and second current signals each having a phase and magnitude which is a function of the phase and magnitude of the phased currents in the first and second windings, respectively. The apparatus includes a circuit for shifting the phase of the second current signal to match the phase of the first current signal, a circuit for detecting a difference between the magnitude of the first current signal and the magnitude of the phase shifted second current signal, and a circuit for disconnecting the transformer from the power source when the detected difference exceeds the predetermiend amount.
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Westinghouse Installation.Operation.Maintenance Instructions (Types HU and HU-1 Transformer Differential Relays), pp. 8-11, FIG. 9, Jan. 1976.
IEEE Transactions on Power Apparatus and Systems, vol. PAS-94, No. 6, Nov./Dec. 1975 (A Three-Phase Differential Relay for Transformer Protection--C. H. Einvall and J. R. Linders), pp. 1-3 and 5-6, FIG. 4.
IEEE Guide for Protective Relay Applications to Power Transformers (IEEE C37.91-1985), pp. 14-15, FIGS. 1, 2, and 6.
Basler BE1-87G Variable Percentage Differential Relay brochure (UBK-3, 11-85), p. 3, FIG. 2, 1985.
ASEA Catalogue RK 62-10 E, Edition 4, Jan. 1978, File R, Part 1 (Transformer Differential Relay Type RADSE), FIGS. 7-8.
ASEA Catalogue RK 62-12 E, Edition 1, Sep. 1979, File R, Part 1 (Transformer Differential Protection Type RADSB), p. 1, FIG. 1.
Basler Specification for BE1-87G Variable Percentage Differential Relay with Drawing No. 9 1708 00 680, FIG. 1, 11-1985.
Basler Instruction Manual for Variable Percentage Differential Relay Model No. BE1-87G (Pub. No. 9 1708 00 990, Rev. B), pp. 1-2 and 3-1, FIG. 3-1, 10-1986.
IEEE Transactions on Power Apparatus and Systems, vol. PAS-104, No. 12, Dec. 1985 (Fault Induced Wave Distortion of Interest to Relay Engineers), p. 3577.
Westinghouse Installation.Operation.Maintenance Instructions I.L. 41-337.3C (Types CA-16 and CA-26 Percentage Differential Relays for Bus and Transformer Protection), pp. 3-4, FIG. 10, 8-1971.
Power Transformer Protection, Part IV (AIEE Trans., vol. 66, pp. 911-915, 1947), pp. 269, and 271-272.
G. E. Protective Relays 7275, Aug. 14, 1978 (Type BDD Percentage-Differential Relays with Harmonic Restraint), p. 1, FIG. 2.
Westinghouse Installation.Operation.Maintenance Instructions I.L. 41-332.2A (Type CA Percentage Differential Relay for Transformer Protection), FIG. 4, Jan. 1966.
Basler Electric Company
Jennings Derek S.
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