Journal ArticleDOI
An improved transformer differential relay
TLDR
In this article, a transformer is energized and there is an inrush of magnetizing current, which flows in only one winding of the transformer, producing a differential current which tends to operate conventional percentage differential relays.Abstract:
POWER TRANSFORMERS usually are protected against damage due to internal faults by percentage differential relays, which compare currents on opposite sides of the transformer. However, when a transformer is energized, there is often an inrush of magnetizing current, which flows in only one winding of the transformer, producing a differential current which tends to operate conventional percentage differential relays. Special means, therefore, are necessary to prevent transformer relays from operating falsely on magnetizing inrush currents.read more
Citations
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Journal ArticleDOI
A Current-Based Solution for Transformer Differential Protection. Part I: Problem Statement
TL;DR: A new approach for transformer differential protection is proposed and a relay that is based on this approach is described and the existing methods for discriminating internal faults from inrush and overexcitation conditions are summarized.
Journal ArticleDOI
A Transformer Differential Relay with Second-Harmonic Restraint
R. L. Sharp,W. E. Glassburn +1 more
Journal ArticleDOI
A three-phase differential relay for transformer protection
C.-H. Einvall,J.R. Linders +1 more
TL;DR: In this article, the harmonic restraint differential relay concept has been enlarged upon to provide a new static multiple-winding transformer differential relay, which includes simplification of the frequency selective circuits and new techniques for rapidly determining the harmonic content of the applied currents.
Journal ArticleDOI
A Microprocessor Based Three-Phase Transformer Differential Relay
James S. Thorp,Arun G. Phadke +1 more
TL;DR: In this paper, simple recursive expressions for the harmonics using a sampling rate of 12 times a cycle were given for a three-phase, three-winding power transformer, which were used as the basis for a one cycle algorithm which was compatible with proposed digital line protection schemes.
Performance Analysis of Traditional and Improved Transformer Differential Protective Relays
TL;DR: This paper describes a new approach for transformer differential protection that ensures security for external faults, inrush, and overexcitation conditions and provides dependability for internal faults and describes the relay that is based on this approach.
References
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Journal ArticleDOI
Harmonic-Current-Restrained Relays for Transformer Differential Protection
TL;DR: In this article, a new type relay is described which, using the principle of harmonic-current restraint, is able to distinguish between the differential current due to an internal fault and that due to magnetizing inrush by their difference in wave form, operating with high speed on the fault current and being restrained from operating by the magnetizing-inrush current.