Topic
Isolation transformer
About: Isolation transformer is a research topic. Over the lifetime, 8145 publications have been published within this topic receiving 72396 citations.
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20 Jul 2008TL;DR: In this paper, the advantages and disadvantages of different interconnecting transformers for distributed generation interconnection are discussed and a neutral reactor sizing for grounding transformer connections is discussed, which is a critical point because the selection of the correct interface with the local utility will simplify feasibility studies; therefore, decreasing the overall cost of the DG interconnect investigation to benefit all.
Abstract: The interconnection of distributed generation (DG) into the power distribution system creates many challenges for utilities. Many of these challenges are related to the type of interconnection transformer (or lack thereof) and consequently the grounding used for the DG interconnection. There remains confusion about the various transformer types for DG interfacing. This is a critical point because the selection of the correct interface with the local utility will simplify feasibility studies; therefore, decreasing the overall cost of the DG interconnect investigation to benefit all. This paper discusses the advantages and disadvantages of different interconnecting transformers. Neutral reactor sizing for grounding transformer connections is discussed.
52 citations
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TL;DR: In this article, the authors provide a technique for design optimization for maximizing power harvest, revealing a critical result: for any given core in any particular application, power harvest is maximized when the core is permitted to saturate at an opportune time in the line cycle.
Abstract: Energy harvesting offers an important design option for creating sensing and control elements without a requirement for custom wiring or batteries. An exciting possibility creates a “self-powered” sensor node with an integrated energy harvester that can extract power from the magnetic fields around a power line to a load, in the manner of a current transformer. However, this “current transformer” provides not just current sensing, but also power for a sensor package, all without ohmic contact. This paper provides a technique for design optimization for maximizing power harvest, revealing a critical result: For any given core in any particular application, power harvest is maximized when the core is permitted to saturate at an opportune time in the line cycle. Circuits for optimizing this power transfer window and experimental results supporting the analysis are presented in this paper.
52 citations
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TL;DR: A flux-based technique is proposed to detect and identify the faulty phase in transformers to apply in online conditions and by using the proposed technique, the faulty region can be identified in offline conditions, as well.
Abstract: Power transformer, as one of the most important apparatus in power system, must be protected against the turn-to-turn faults. Although the various methods based on the terminal currents and/or voltages have been presented for transformer protection, the flux-based methods can be used to achieve the more accurate, sensitive, and secure results. Since the symmetrical form of the magnetic flux distribution will be disturbed due to any fault occurrence in the transformer windings, it can be considered as an appropriate criterion to achieve a suitable protection algorithm, which can detect the fault occurrence and identify the faulty phase/region. In this paper, a new leakage flux sensor is introduced and then a flux-based technique is proposed to detect and identify the faulty phase in transformers to apply in online conditions. By using the proposed technique, the faulty region can be identified in offline conditions, as well. The experimental results (which are done on a distribution transformer) show that this technique is secure in the face of overfluxing and transformer energizing conditions and can detect turn-to-turn faults with high sensitivity. Moreover, tap changer operation, imbalanced loads, and/or unsymmetrical voltage sources cannot influence the proposed technique security.
52 citations
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TL;DR: In this paper, a physically consistent dual model for single-phase two-winding transformers for low-frequency transients is proposed. But the model remains invariant for all low-frequency transients including deep saturation conditions driven from any of the two windings.
Abstract: This paper presents a physically consistent dual model applicable to single-phase two-winding transformers for the calculation of low-frequency transients First, the topology of a dual electrical equivalent circuit is obtained from the direct application of the principle of duality Then, the model parameters are computed considering the variations of the transformer electromagnetic behavior under various operating conditions Current modeling techniques use different topological models to represent diverse transient situations The reversible model proposed in this paper unifies the terminal and topological equivalent circuits The model remains invariable for all low-frequency transients including deep saturation conditions driven from any of the two windings The proposed model is tested with a single-phase transformer for the calculation of magnetizing inrush currents, series ferroresonance, and geomagnetic-induced currents (GIC) The electromagnetic transient response of the model is compared to the π model and to laboratory measurements for validation
52 citations
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10 Oct 1969
TL;DR: In this paper, the authors describe a ground integrity detector circuit with two voltage stepdown transformers connected in series with one another and with the sensor, which is intended to be connected to a remote ground terminal as well as the ground terminal of the line voltage source.
Abstract: A circuit for use with a sensor located in a hazardous area such as in an atmosphere of explosive gases, organized to prevent electrical power at the sensor from exceeding prescribed levels even upon reasonably foreseeable failures of parts of the circuit. The circuit, which is located in a nonhazardous area, includes an indicator, such as a relay-controlled alarm, to respond to the sensor, and terminals for connection to a source of line voltage. Two voltage stepdown transformers have their secondaries connected in series with one another and with the sensor. The primary of one transformer is connected to the line voltage source; and the primary of the other transformer is connected to the indicator. Each transformer secondary lies intermediate a pair of current-limiting resistors, and the primary and secondary windings of each transformer are isolated by means of a grounded conductive sheet. Each transformer, along with its associated current-limiting secondary resistors, is embedded in potting material to form a self-contained isolating circuit module. The circuit is intended to be connected to a remote ground terminal as well as the ground terminal of the line voltage source. A ground integrity detector circuit interrelates these three terminals by means of resistances and a neon glow tube is provide a signal whenever one of the ground circuits is lost, as well as a signal upon failure of one of the resistances forming the ground integrity detection circuit. The remote ground connection has a path extending through the circuit chassis to insure that its ground is maintained.
52 citations