Innovation of a Control Transformer Design

The present article deals with an innovative design of a control transformer. It describes a conventional design of a control transformer and provides the basic theoretical information on control transformers which is available in the world technical literature, patents, as well as other available sources addressing this topic. Subsequently, the article describes a novel, original design and presents the related drawing documentation.

An Eco-Friendly Gas Insulated Transformer Design

Electricity companies around the world are constantly seeking ways to provide electricity more safely and efficiently while reducing the negative impact on the environment. Mineral oils have been the most popular transformer insulation, having excellent electrical insulating properties, but have many problems such as high flammability, significant cleaning problems, and are toxic to fish and wildlife. This paper presents an alternative approach to mineral oil: a transformer design that is clean and provides better performance and environmental benefits. A 50 kVA, 34.5/0.4 kV gas insulated distribution transformer was designed and evaluated using the COMSOL Multiphysics environment. R410A was used as insulation material. R410A is a near-azeotropic mixture of difluoromethane (CH2F2, called R-32) and pentafluoro ethane (C2HF5, called R-125), which is used as a refrigerant in air conditioning applications. It has excellent properties including environmentally friendly, no-ozone depletion, low greenhouse effect, non-explosive and non-flammable, First, the breakdown voltage of the selected gas was determined. The electrostatic and thermal properties of the R410A gas insulated transformer were investigated in the COMSOL environment. The simulation results for the performance of oil and SF6 gas insulated transformers using the same model were compared. The gas-insulated transformer is believed to have equivalent performance and is an environmentally friendly alternative to current oil-based transformers.

Design Analysis of High Frequency Linear Transformer with Ārtap Framework

This paper presents the design and a design analysis of a coaxial, linear transformer. This is a novel high frequency transformer concept for energy conversion. The examined transformer was designed for 1 MHz nominal frequency. One of the main advantages of the proposed transformer design is its simple winding system. It contains only two coaxial copper tubes, which can be easily manufactured and modeled with high precision. One of the key design tasks is the minimization of the leakage inductance. The inductance of the straight coils depends on the ratio of the height and the diameter of the coil. Therefore, a three-dimensional FEM analysis is sufficient to calculate the optimal length of the linear transformer. The planar 2D model and the 3D model of the transformer are presented in this paper. The accuracy of the 2D and 3D calculation results were compared to each other and to the measurements to show the applicability of the planar 2D models. Moreover, the sensitivity of the losses and the leakage inductance with respect to the winding parameters is presented. The dependencies of the design variables on the performance parameters, such as the power mass density and the leakage inductance of this transformer concept were examined. It was shown that the value of the leakage inductance is a linear function of the ratio of the length and the diameter of the transformer windings.

Ac loss modelling and measurement of superconducting transformers with coated-conductor Roebel-cable in low-voltage winding

Power transformers using a high temperature superconductor (HTS) ReBCO coated conductor and liquid nitrogen dielectric have many potential advantages over conventional transformers. The ac loss in the windings complicates the cryogenics and reduces the efficiency, and hence it needs to be predicted in its design, usually by numerical calculations. This article presents detailed modelling of superconducting transformers with Roebel cable in the low-voltage (LV) winding and a high-voltage (HV) winding with more than 1000 turns. First, we model a 1 MVA 11 kV/415 V 3-phase transformer. The Roebel cable solenoid forming the LV winding is also analyzed as a stand-alone coil. Agreement between calculations and experiments of the 1 MVA transformer supports the model validity for a larger tentative 40 MVA 110 kV/11 kV 3-phase transformer design. We found that the ac loss in each winding is much lower when it is inserted in the transformer than as a stand-alone coil. The ac loss in the 1 and 40 MVA transformers is dominated by the LV and HV windings, respectively. Finally, the ratio of total loss over rated power of the 40 MVA transformer is reduced below 40% of that of the 1 MVA transformer. In conclusion, the modelling tool in this work can reliably predict the ac loss in real power applications. This is the Accepted Manuscript version of an article accepted for publication in 'Superconductor Science and Technology'. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/0953-2048/28/11/114008.