Leakage reactance variation in dry-type transformers due to spacer positioning: A FEM and experimental study

Because of high productivity, closer dimensional tolerances, and minimal material waste precision forging (net or near net shape) processes have been used for manufacturing automobile components. The primary disadvantage of precision forging is the encountered higher tool stresses due to applied higher forging loads. Thus, forging load reduction is a higher priority in precision forging in terms of energy consumption and cost because higher loads required higher investment and higher energy consumption. Forging load is affected by several parameters such as temperature, material flow, the geometry of the billet, and punch movement. In this study, forging load, material flow, and normal pressure distribution in the forged part were investigated considering uni-directional, bi-directional, and two-step forging processes. FEM simulations were performed by using a solid cylindrical billet. To perform FEM simulations, the finite element analysis package (DEFORM 2D) was used. Also, experimental studies of the FEM models were performed. For bi-directional and step-forging experimental studies, a double-acting servo press was used because the movement of the top and bottom punch can be controlled accurately. Then the results of FEM and experimental studies were compared with each other. The results of the FEM simulations and experimental studies show two-step forging offers lower forging load and energy consumption whereas the uni-directional closed die forging process needs higher load and energy consumption

Hyperelastic and viscoelastic properties of recycled rubber material – experimental and fem characterization study

Power transformers are crucial parts of electrical power systems. Electromagnetic parameters, especially leakage inductance and reactance, have a big impact on how well and reliably they work. Leakage inductance has an effect on voltage regulation, transient response, harmonic behavior, and short-circuit performance. In renewable energy systems, such as wind, solar, and hybrid microgrids, dry-type transformers play a vital role in ensuring stable voltage conversion and efficient integration of distributed generation sources into the grid. This paper discusses an experimental study of transformer leakage inductance, concentrating on the impact of conductor thickness. The study involves systematically varying the winding thickness and measuring the resulting leakage inductance, load losses, leakage reactance, and no-load losses. The experimental results demonstrate how changes in conductor thickness influence leakage inductance and associated performance characteristics, offering design insights for improving efficiency and reliability of transformers used in renewable energy applications. This work provides practical guidance for transformer design to balance electrical efficiency and thermal stability.

The stand is taken that the resolution of the leakage reactance of a pair of windings into the individual reactances of the two windings is indeterminate unless referred to a third winding and that therefore it varies with the object in view when making the resolution. If the object is the influence of exciting current on performance, the problem is converted into a three-winding transformer problem by conceiving of the exciting current as produced by a (fictitious) load in a (fictitious) third winding. It is pointed out that the resolution of leakage reactance into individual reactances is possible only in the case of three windings, and that therefore in a transformer with three real windings and a fictitious exciting-current-load winding, constituting the equivalent of a four-winding transformer, the simple resolution fails, each winding having a different individual leakage reactance when associated with one pair of the remaining windings than when associated with another pair. Furthermore, the resolution made from the standpoint of real load currents will be different from that made from the standpoint of exciting current. Formulas are given for such resolutions, and experimental methods are described. The problem is also considered from the standpoint of flux distribution and linkages, and the limitations of some common views are pointed out.

Chromium–nickel steels are widely used in various fields of the engineering practice because of their increased corrosion resistance. One of the most used chromium–nickel steel is AISI 316Ti. It is known from the engineering practice that processing this steel by cutting creates difficulties and problems. However, there is no information regarding the effectiveness of the slide burnishing (SB) method in terms of quality of the processed surface of this chromium–nickel steel. A comprehensive experimental and FEM study of the surface integrity of slide burnished specimens made of AISI 316Ti austenitic stainless steel has been carried out. The effect of the SB parameters on the obtained roughness, microhardness, residual stress, fatigue strength (life) and wear resistance has been studied. A fully coupled thermal-stress FEM analysis has been conducted to be appreciated the effect of the generated temperature in SB process on the residual stress formation. The SB of AISI 316Ti steel achieves: roughness of Ra = 0.055 μm; micro-hardness increased by more than 32%; significant wear resistance; introduced residual stress with a maximum absolute value, which significantly exceeds the yield limit of the bulk material; increased fatigue strength by 38.9%; fatigue life increasing more than 385 times. The obtained experimental outcomes for the main characteristics of the surface integrity prove that SB can be successfully applied as a mixed burnishing for finishing symmetrical rotational components made of chromium–nickel steels.

Theoretical, numerical and experimental studies are described that have been carried out to develop a solid-rotor induction machine design for a particularly demanding application as an accelerator drive for a diesel engine turbocharger. In this application the turbo-motor will be required to operate at speeds of up to 130 000 rpm and in temperatures that can exceed 200°C. The results show that the equivalent circuit gives predictions that are of sufficient precision for design purposes and provides a useful design tool. It is shown that the use of a solid rotor affects the value of the stator leakage reactance and influences the motor performance through this effect as well as by presenting a high rotor resistance.