Anca-Simona Deaconu

PLC controlled elevator drive system

This paper presents a control method for an advanced electrical drive system for transportation, namely an elevator. For cost efficiency the control is performed with the simplest appropriate PLC. Thus, the software code was wisely developed to be fast and small size. Starting from an educational platform, which models a two floor elevator using a DC electrical drive, different sensors types and a PLC, the development of the actual driving sequences and PLC program, written using ladder diagram language, is detailed. In order to account for various normal operation and malfunctioning scenarios, some testing techniques are presented as well as their implemented into the PLCs program. Thereby, the paper has also an instructive aspect for engineers working in the automation field.

CAD for three phase ONAN cooling system transformers

This paper presents a Computer-Aided Design method for a three phase power transformer using MATLAB programming environment. The considered transformer is Oil Natural Air Natural cooling system type. During the designing by changing the value of just one single variable implies to recalculate everything. Such operation is time consuming but this drawback can be overcome by fully automating the design procedure, for example using MATLAB. The developed program is written in script format so that it can be easily modified to fit the imposed parameters of the transformer. The designing algorithm of the transformer has been optimized. Thus, it has ten steps with nine validation checkpoints. It may also be used as an educational model. The validations are implemented into the code and are required because there is no sure-fire method for designing a transformer from the first attempt. During the design it is necessary to change various values. Thus, only when all nine verifications are satisfied one may conclude that the transformer is well designed.

Educational platform for working with programmable logic controllers

The restructuring and the reorganization of the educational teaching system has comprehended not only the academic teaching curriculum and management system but also the teaching methods. Educational platforms and virtual laboratories are increasingly becoming a key component during the teaching process especially for technical teaching. Although the existence of virtual laboratories and e-learning platforms can be very useful tools for electrical engineering in particular they will never replace real laboratories. The main reason is that using real educational platforms the students have the opportunity to become familiar with the basic principles and real elements of a particular area. Moreover, they can develop various complex applications and test their behavior. In the end, the main objective is that the present students - future engineers should be able to both operate real world systems and implement designed solutions that are likewise the teaching platforms. In this vein it is proposed a platform based on the programmable logic controllers (PLC) technology that has not been done so far. It is designed to be open enabling to add new modules and features. While the considered platform is based on a specific brand of PLC it can be very easily adapted without major technical issues to other brands.

Petri net versus Ladder Diagram for controlling a process automation

Industrial automation is constantly expanding, and, regarding their control more and more solutions are presently developing on the market. These include older methods like Petri nets (1966), and standardized languages, which are commonly used in the field of programmable logic controllers (PLCs). The paper presents the Ladder Diagram programming language, that is one of the standardized languages, and one of the most widely used for industrial automation systems. In these circumstances, it is useful to make a comparison between the two methods, drawing out the advantages and the disadvantages of each solution separately. Petri nets benefit from the existence of a highly developed mathematical support and high flexibility in analyzing all elements that can influence the conduct of an event, which is a major advantage. On the other hand, the Ladder Diagram language, which corresponds to the standard IEC 61131, is easy to use and implement, regardless of the hardware structure used by the manufacturer. Also, this method allows both ON-line and OFF-line simulations of the automation process operation. Finally, an educational platform is also presented.

Quality analysis of an educational website regarding the server traffic subject of analysis: www.electro.pub.ro Server

It has been studied the quality of a website with educational character from the point of traffic seen on the host server and accessed most keywords.

Noise analysis for no load operating power transformers

In this paper is presented a statistical analysis of the sound power emitted by power transformers. The power of the analyzed transformers within this analysis is greater than 6 MVA in no-load operation when the cooling system is turned off. Using this statistical approach the complex multiphysics problem of estimating the transformer sound power is greatly simplified.

Computer numerically controlled device

In the industry, prototyping is an unavoidable step. The three-dimensional (3D) models of prototypes are relatively easy to develop with the help of dedicated 3D software. The difficulties step in when the prototypes have to physically be manufactured. Moreover the manual prototyping is time consuming, expensive and sometimes requires specialized crafting in order to obtain alike parts that would behave similar during strength tests. The entire snag fades away when computer numerically controlled device is used. It is capable to process a wide range of materials (e.g. steel, aluminum, wood, glass) and reproduce with high accuracy identical items based on the 3D model designed with a computer. The prototype or small series production is cheaper and faster due to the repeatability of movements during the manufacturing process. In the paper are highlighted the steps and the requirements that must be followed in order to develop a 3-axis computer numerically controlled device.

Thermal analysis of a PMSM for an intermittent periodic duty cycle

Within electric drives in industrial area and beyond the permanent magnet synchronous machines (PMSM) are increasingly and widely used. This type of machines offer several advantages compared to squirrel-cage induction machines that are replaced in many electric drives types. Some of these advantages are the increased power density, require similar control methods to induction machines and not lastly most of the permanent magnet synchronous machines do not require cooling fan, which contributes to an increased overall efficiency. Due to the lack of forced cooling an important issue that it is analyzed is the heating of the machine with respect to the applied control method. The PMSM is fed using two types of powering when considering an intermittent period duty cycle.