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In this paper we describe the development of a small, office-friendly CNC machine. We compare popular CNC archetypes and their ability to be operated in a non-workshop environment. We have made an enclosed machine that is safe both for the operator and people nearby and clean to use, with outer walls fully integrated into the frame for improved rigidity. We made some unique design decisions for increasing the working area without sacrificing stiffness in a small form factor CNC. [ABSTRACT FROM AUTHOR]

A proper and successful methodology of electrical contact design is achieved by combining the theoretical and practical studies. This paper presents an instructional approach involving FEM simulations in order to aid in the practical operations on electrical contacts in MV and HV electrical apparatuses effectively. Prior to the completed engineering and scientific work in the field of the electrical apparatuses, constructing the FEM-based model is an effective way to achieve and understand the pros and cons of the experimental solutions. This design method is widely used by the industrial companies and can be implemented as an educational method giving young engineers a new edge. The desired effect of the proposed course was to develop student understanding of electrical contacts engineering by combining the theoretical (simulations) and the practical approach. Ordered creativity was successfully put into practice by checking the parameters derived from the simulations on the real scale layout, which affected and enhanced student confidence in the field and in engineering skills. This instructional approach consisted of two sections (The Theoretical and the Practical) and is essential for understanding and further exploiting the acquired knowledge and certain other measures in engineering work. Moreover, it renders a complete engineering experience employing consequences and their impact on experimental electrical contact research based on multitasking and diversity. The statistical analysis proved that the proposed method had a significant impact and yielded improved results. Moreover, a major improvement in student learning and satisfaction after participating in the proposed course was noted. [ABSTRACT FROM AUTHOR]

The purpose of the proposed course is to enhance students' knowledge, engineering skills and understanding in the field of electrical contacts power engineering – the currents of contact welding. The main goal for students is to acquire brief skills concerning measurements of certain parameters using static layout: currents that cause contact welding, clamping force of contacts joints and breaking force. Moreover, students are encouraged to obtain soft skills like confidence in the mentioned field and creativity. Student work during the exercise is evaluated on the basis of report from laboratory work and test. Essential aspect is safety training while working with HV and MV switchgears – that is another obligatory feature which participants will obtain from this course. Course results were evaluated as significant on the basis of concluded statistical analysis and comparison to previous formula employed during the classes. [ABSTRACT FROM AUTHOR]

This paper aims to discuss the behavior of the proprietary real-time simulator (RTS) during testing the coordination of distance relay protections in power engineering. During the construction process of the simulator, the mapping of various dynamic phenomena occurring in the modeled part of the power system was considered. The main advantage to the solution is a lower cost of construction while maintaining high values of essential parameters, based on the generally available software environment (MATLAB/Simulink). The obtained results are discussed in detail. This paper is important from the point of view of the cost-effectiveness of design procedures, especially in power systems exploitation and when avoiding faults that result from the selection of protection relay devices, electrical devices, system operations, and optimization of operating conditions. The manuscript thoroughly discusses the hardware configuration and sample results, so that the presented real-time simulator can be reproduced by another researcher. [ABSTRACT FROM AUTHOR]

Along with the increase in the use of nonlinear electronic devices, e.g. personal computers, power tools and other electrical appliances, the requirements for uninterruptible power supplies are constantly growing. This paper proposes a method and deep analysis of results viable for checking how single-phase uninterruptible power supplies (UPSs) cope with nonlinear circuits under varying power loads in terms of electric energy quality. Various classes of single-phase UPS systems with different topologies were tested, for instance line-interactive and double conversion (online) single-phase UPS devices. Furthermore, measurements were carried out in view of a power source - loads were supplied both from a power grid and UPS built-in battery. Juxtaposition of the obtained results such as a THDU, THDI (Total Harmonic Distortion) percentage ratio of input/output voltage and current, a power factor and crest factor volume etc. of the tested UPS systems indicated major differences in their performance during laboratory tests. [ABSTRACT FROM AUTHOR]

The purpose of this work is to discuss the tulip contact behavior during mechanical and electrical simulations in a Finite Element Method (FEM) environment using ANSYS and COMSOL software. During the simulations, the full contact movement was analyzed. During the contact movement, the individual behavior of the contact components was taken into consideration. The motion simulation was carried out at different velocities and forces acting on the contact. The obtained results were compared to each other and discussed. Relatively, the angles of the contact surfaces to each other were also changed, which meant that we could conduct a more in-depth analysis. The other approach of simulation research was a field analysis of physical phenomena occurring in the tulip contact. This analysis was performed in COMSOL Multiphysics. Parametric analysis allowed an observation of the electric field in the tulip contact at different contact distances with respect to each other. This work is important in terms of the cost effectiveness for design procedures concerning tulip contacts and fault avoidance, which both result from mechanical and electrical conditions throughout contact exploitation and optimization of the working conditions for the tulip contact. [ABSTRACT FROM AUTHOR]