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This paper presents a fuzzy-logic algorithm for predictive maintenance (Industry 4.0) and at the same time for future design improving, applicable for high voltage equipment (switches, surge-arresters, etc.). Starting from this algorithm a software tool can be developed tool for high voltage equipment maintenance. It is an example of implementing advanced mathematical and software solutions for the maintenance of operational high voltage switching equipment (and other high voltage devices, too). For testing and validating the algorithm experimental data (and also experimental setups) were operated from the industrial environment (manufacturers and users of that equipment) and used for conceiving a monitoring and diagnosing digital based procedure, both for a more efficient design of that equipment as well as for efficiently assess the technical state of their main HV contacts. The results obtained are encouraging and recommend the use of the algorithm on a larger scale.

Metal oxide varistors (MOV) are the newest and most advanced category of overvoltage protection elements, with obvious advantages. They are manufactured in an extremely wide range of construction, for each voltage level, from telecommunications networks and low voltage electrical installations to high and very high voltage networks, regardless of the type of current (AC or DC). This paper presents an original overvoltage protection module designed to operate in the automotive environment, based on Metal Oxide Varistors. Some design feature and experimental results are also presented in the second part of the paper.

The unprecedented expansion of urban areas is a great challenge, but also a great opportunity to develop new technologies and services that will change the way we see and perceive our society. The exponential improvement of our electronics, telecommunication/information technologies, and the lower cost of production, allows us to solve complex challenges and bold leaps in the development of urban areas. This article proposes a solution for integrated utilities, addressing the challenges that come with large telecommunication, water, gas and electricity networks, in order to provide services at a low, reliable and sustainable price. For the future, it is expected that millions of distributed, storage and management power generation systems, but equipped with autonomous intelligence and automation to increase the economy, sustainability, reliability and security of technicalmunicipal networks.

Because the internet broadcasting, most photos or video streams need copyright protection or forgery detection. Nowadays, the metadata tries to embed and preserve copyright data and general information. The ownership metadata should never be removed, for an efficient protection, but practically it could be relatively easy extracted. This research proposes, based on a comparison between metadata and watermarking methods, a watermarking framework that inserts visual and hide information into digital images, instead of metadata protection. The visible watermark inserted into the host image could be removable or not, based on the bijective or non-bijective embedding watermark function. A removable watermark allows the far end receiver to eliminate the visible watermark, whether it uses a framework that uses the invers embedding function. In this way, only the controlled receivers could profit by the clean photos/video stream. More of this, the hidden watermark could embed typical information that identify the owner.

In the area beyond each high voltage overhead line or around any high voltage power equipment, integrated inside power stations or operating alone, high values of the electric field intensity (and/or magnetic field induction) accidentally occur. Certain preventive safety measures, both for the environment, as well as for the human personnel, are mandatory. An objective and fair assessment of the electric field intensity around all these facilities is mandatory, before considering any new design features or limiting the operational exposure. This paper shows some measurements of the electric field intensity, performed at the Fantanele 220kV/110kV/20kV Power Station, located in Central Transylvania, Romania. This power station is belonging to the National Romanian Power Grid Operator, TRANSELECTRICA S.A. Our case study is also filled with some electric field measurements, added to describe the electromagnetic field parameters. Data collected will be also used for the refurbishment of some existing power facilities in Romania and for a dedicated digital map of this potentially high-risk power objectives.

In the area of all power stations, or in their close proximity, there are, in some situations, high values of the magnetic field induction and/or electric field intensity. In many cases, low frequency electromagnetic fields are not taken in consideration, until recently, as dangerous for humans. A realistic and objective assessment of the electromagnetic field (magnetic field induction and electric field intensity) in the proximity of these facilities is a major step before designing new safety measures, suitable both for environment, as well as for human operators. This article presents a database, populated with measurements of these two main parameters measured inside or close to some major power stations, located in the Central Transylvania Region of Romania, belonging to the National Power Grid Operator, TRANSELECTRICA S.A. The newly created database will be the start point to build a digital map of field exposure for all the considered stations, before reducing or eliminating human exposure on certain dangerous zones. The given database could be also used for the refurbishment or construction of new safety features.

This paper aims to present a simple and original algorithm, completed by generating a dedicated software, performed for obtaining an optimisation of the typical engineering schedule graph established for a real highway segment, located in the West Region of Romania. The main issue for construction schedule was the interdependence and the time relations between all phases. The Critical Path of the whole construction sequence was designed by using the Ford Algorithm. By implementing this procedure, we obtained a more accurate operation overview in case of all major phases belonging to the construction engineering on site, by simply emphasizing the time correlations between all its phases and/or operations. This originally applied software sequence could be a very simple and easy to use tool for other engineering applications, in all industrial or construction domains.

The main issue of this paper is to design a controller for Discrete Event Systems (DES), based on the Supervisory Control Theory (SCT), applied in transport or logistic areas. This theory is used mostly for command and control of many cybernetic, manufacturing, communication, military or transportation as well as many others. The controller designed for the DES applications is currently named as a supervisor. The SCT based applications involve many dedicated languages and automation concepts taken from the classic control domain. By using SCT, any logistic chain can be modeled by using automation sequences. The automation itself is a true event sequence generator. The desired and controlled behavior of that logistic system is clearly defined by its specifications. By using SCT elements, any supervisor can be particularly synthesized, avoiding the transportation to reach some undesired states. After defining all operations, the resulted supervisor can be implemented in practice to perform real control tasks. Programmable Logic Controllers (PLCs) are widely applied for control tasks in today industry, and, by consequent, the supervisor for an industrial logistic chain could be implemented by means of PLCs. The language which is mostly used for programming PLCs is based on the Ladder Logic Diagram (LLD). Any supervisor described in an automation sequence form could be easily converted to an LLD code. As an example, in this paper, a small manufacturing system that consists of two machines and a buffer is considered. All pieces must be vehiculated between the machines on a simple logistic sequence, depending on their state. The implementation of the supervisor is also provided.

The Supervisory Control Theory (SCT) is a general technique used to design a controller for Discrete Event Systems (DES) such as production/manufacturing systems, cybernetic systems, communication systems, transportation systems and many others. Resulted controller for the DES is named a supervisor. The SCT involves many formal languages and automata concepts for supervisor synthesis. In SCT, any manufacturing plant can be modeled by using automata. This automaton is a true event sequence generator. By using SCT, a supervisor can be synthesized for avoiding plant from some undesired states in all conditions. The Programmable Logic Controllers (PLC) is widely used to perform control tasks in modern industry. It is also clear that, the supervisor is commonly implemented by means of PLCs. The most popular computing language for programming PLCs is Ladder Logic Diagrams (LLD). The supervisors in automata form can be easily converted to LLD code. In this paper, fundamental information about SCT is presented. As an example a small manufacturing systems that consist of two machines and a buffer is considered. This is a new approach for solving an industrial process issue consisting on a PCB which is transferred from a component soldering machine to another, using a buffer. The implementation methodologies of all supervisor techniques are also provided, in order to increase the speed/productivity of the whole process.

Power transformers are probably one of the most complicated and most important equipment working inside the power transmission and distribution system. The assessment of the technical status is performed with the double purpose of extending its life and to reduce all risks. It is a complex and important task, depending on the role of that transformer inside the system. It could be a routine set of investigations or special investigations that appeal to the latest techniques and methods of measurement. In order to get a correct diagnosis, the measured data must be as accurately obtained, correlated and evaluated starting from the applicable technical regulations, the latest recommendations and information from the literature, and based also on the similar technical experience. This paper will present a case study for the variation of the load efficiency (the efficiency) as well as some economical aspects, based on real measurements and technical data sheet parameters.

The power transformer is probably one of the most complex and most important equipment existing in the power transmission and distribution system. The evaluation of the technical condition, done with the double purpose of extending its life and reducing the risk of defect, is a complex and important activity, depending on the importance of the transformer in the system. Whether it's routine investigations or special investigations that appeal to the latest techniques and methods of measurement, in order to get a correct diagnosis, the measured data must be as accurately determined, correlated and evaluated on the basis of applicable technical regulations, the latest recommendations and information from the literature, and last but not least, the similar experience. This paper will show a case study for the variation of the load efficiency (the yield) as well as some economical aspects, based on real measurements and technical data.

In the proximity of high voltage overhead lines or high voltage power equipment located inside power stations, high values of the magnetic field induction (and/or electric field intensity) could appear sometimes, too. Safety measures, both for environment as well as for human operators are mandatory. The realistic assessment of the magnetic field induction nearby these facilities is one important stage before adopting new design features or limiting the human exposure. This paper presents some measurements of the magnetic field induction, taken by our team, mostly at the Fantanele 220 kV/110 kV/20 kV Power Station, located in the Central Region of Romania and owned by the National Power System Operator, TRANSELECTRICA S.A. This case study will be completed with some electrical field measurements, for a better perspective on the electromagnetic field parameters. Data is also used for the refurbishment of the existing power facilities.

This article describes a solar energy system, operating off-grid, having either a single photovoltaic panel - PV, or a group of multiple PVs, grouped in a simple solar battery-SB, directly supplying an electric battery-EB, or a group of EBs, having no DC-DC adapter (a buck, a boost or a combination of them, a classic solution available on the market). That SB must be adjusted to the voltage of the EB, in order to supply the same amount of electric energy as when the system functions at its mathematically detected maximum power operating point, on a MPP command strategy. This newly discussed technical solution could be less expensive, compared to the actual one which involves a SB, a DC-DC converter and the EB. It is a cost reduction because that DC-DC converter is no longer used at all. It requires a computer aided model for implementing the current-voltage characteristics. The results of this model will be compared with the classic DC-DC converter solution results, in order to prove validity.

The modernization of existing power generators is one of the key priorities of electricity producers around the world. In order to achieve the digital interconnection of synchronous generators, located largely in hydro-power plants, it is necessary to use an appropriate excitation system. This paper presents an overview of the main objectives to be met by electricity producers in Romania. A model for experimental studies is also presented. The main purpose of this paper is not only to present the current situation in this field, but also to identify some solutions and trends regarding the modernization of the existing generators, in order to meet the requirements of the existing norms and standards, system and the software, and, also, testing its operational efficiency.

Many industrial or domestic applications contain non-linear loads (converters, UPSs, process computers, LED lamps) that generate higher harmonics and distortions in the waveform spectrum of the absorbed current. When operating far from the sinusoidal shape of the current passing through the transformer, its windings generate additional losses, complementary to those of the permanent sinusoidal mode, thus reducing the transformer charging capacity (which has been designed for purely sinusoidal regimes). Therefore, in order not to cause supplementary heating inside its constructive elements, it is necessary to assess its power in relation to the level of the deforming regime.

This paper presents a simple algorithm, forwarded by an adequate software, performed in order to obtain an optimisation of the engineering graph developed for a real 400 kV Over Head Power Line, located in the West Region of Romania. The Critical Path of the whole construction sequence was determined by using the Ford Algorithm. We obtained a more accurate operation overview for all major phases on the construction site, by emphasizing the time relations between all these phases/operations. The newly applied software could be useful for other engineering applications, in all domains.

In low-voltage electrical installations, power issues having the highest incidence are related to the presence of higher harmonics in the waveform spectrum of the absorbed currents and also to the imbalances in the three-phase distributions. The deforming (non-sinusoidal) regime becomes even more undesirable for networks having a low short-circuit response factor (high impedance systems) and, normally, it also causes distortion of waveforms of the supply voltage. Current unbalance (more rarely) is typically seen in networks that supply single-phase consumers (where virtually no balancing is possible on each phase) causing unwanted effects in installations. In this paper, we will investigate how the neutral conductor should be dimensioned inside low-voltage three-phase electric installations, where these deforming modes and / or load imbalances may occur. A new algorithm, easy to implement in any software environment, dedicated for dimensioning the neutral conductor of that installation, will be also described.

This article will present an off-grid photovoltaic energy system based on a photovoltaic element (PV), or a group of PVs, integrated in a solar battery (SB), directly connected to an electrical battery (EB) having no DC-DC adapter (use of adapters is the most common solution existing now on in this domain). This SB must be properly adjusted to the EB, not only as voltage, but it must provide also the same amount of energy as the system when operating at its classically detected maximum power operating point. This proposed technical solution is more economically justified, compared to the classic one: SB+DC-DC+EB, due to the simple fact that the DC-DC converter is no longer required at all. A simple mathematical model for the current-voltage characteristics is also presented, followed by a comparison between the classic DC-DC converter-based solution and the newly proposed one, without DC-DC converter.

Metal Oxide Varistors are a very common power electronic device, applied for efficient overvoltage protection at any voltage level. This piece of equipment has a high non-linear current response function of the applied voltage, and, it provides a relatively high heat absorption capacity in case of accidental overvoltage pulse (shock)s. The crossing response current is clearly activated by temperature of that device, and, by consequent, overheating could be disastrous. Actual researches must be carried out both for a new more performant material as well as for new technical solutions for the design of all equipment integrating them, by studying heat extraction and heat transfer inside a new complex varistor device. Our article proposes a totally new device, used basically for low voltage applications, having a supplementary metal mass added to the body of that varistor, shaped as small disk. It actions like a heat pump immediately after the voltage pulse (shock) and as additional radiators at the end of the heating process caused by a transitory overvoltage. A CAD solution combined with a finite element model, followed by some experimental results are also presented, for confirming the performance of that newly design. By placing additional metal alloy masses inside a new varistor structure it will have a higher heat pumping and dissipation capability, in order to reduce temperature stress and all aging effects.

This article will discuss about the improvement of a simple radio frequency (RF) front-end transceiver unit located into an embedded system taken from the automotive industry, as part of a remote keyless entry (RKE) car system. The main objective is to reduce its size and complexity as well as to reduce radiation. Some impedance tests on the existing and on the proposed model were also carried out.

This paper will briefly present some simulations about a small antenna, part of a TiS (Tire Info System) used to constantly measure pressure inside that car wheel, and to send data to a Central Unit. We will analyze the behavior of this antenna, mounted alone, on different positions inside the tire, ignoring the metallic rim or the metallic tire reinforcement, as impedance and efficiency.

Having excellent dielectrical properties combined with other good physical properties, polymers are used today for the electrical insulation of underground high voltage power transmission cables. Considering the microscopic level, these dielectrics are not homogeneous. They have a structure of amorphous and crystalline regions and the junction between these regions is the host of hopping regions. Thus, this microscopic inhomogeneity is providing substantial space charge at this microscopic level. The existence of space charge offers an electric stress enhancement, which may reduce the lifetime of the whole material. Complementary, the electric strength of the HV/MV cable is affected by the presence of that cavities (voids) in the insulating region. In service, when the whole insulation is subjected to electrical, mechanical and thermal stress, these cavities may lead to a larger discontinuous region. This paper treats, by simulation, the combined effect of space charge and cavities on the electric field, electric potential and temperature distribution within solid insulation. The values of their magnitudes in cavities are calculated, enabling us to envisage if partial discharges appear in these weak parts.

Power conversion using electrical machines is always accompanied by power losses (active and reactive) and implicitly by losses of electricity in all the elements of that given electrical network topology. The level of energy losses in the electrical machines operating as motors oscillates in the range between $\mathbf{5}\div \mathbf{25}\%$ of the active energy supplied, depending on the structure of the electrical network, the operating conditions of the motor, its parameters etc. Most of that energy is lost as heat, but there are magnetization losses too. This paper will describe a new computational method for active power assessment and will test it with measurements on a real 160 kW asynchronous motor powering a mixing unit. It is a simple algorithm which could easily be applied for each electrical machine in service, by the owners of that drive, using simplified equipment.

Metal Oxide Varistors are, from the chemical point of view, ceramics, acting as n-semiconductors and having a poly-crystalline and complex structure. The main application of these power electronic devices is for construction of overvoltage protection equipment (for every voltage level), because of some advantages like: an increased level of non-linearity between the resulting current and the voltage characteristic, a high energy adsorption capacity and an excellent fast response time, which make them ideal for protecting other sensible electronic devices and circuits. This paper presents a new material and some manufacturing technology aspects for a Metal Oxide Varistor based on a new mixture of oxides used in order to obtain a new ceramic with higher non-linear electric properties. The two oxides involved are Cr 2 O 3 and MnO 2 as dopants or additives. All measurements of the electrical performances will be carried out in relation with an existing 5 dopants material (three +these two).

Underground low voltage cables as well as medium voltage ones (AC and DC) still present insulations made of special paper. The most important issue of this simple and efficient material is ageing, especially under stress conditions. This research tries to establish a mathematical model (based on computer implemented numerical methods) which can easily characterize the ageing process of the dielectric material even under cyclic voltage stress, in case of DC low voltage cables. Focused on the evaluation of the threshold value of charge accumulation by use of parameters derived from PEA measurements, the article investigates the space charge evolution under cyclic stress of papers for DC cables applications.

Protection of any sensitive piece of electric or electronic equipment against accidental overvoltage occurrence (mostly lightning strokes applied to power networks) is a constant concern for the power electronics domain. The most performant and reliable devices, used as main components to perform this operation, are Metal Oxide Varistors (MOV, or ZnO) surge-arresters. These complex devices are ceramic materials, including different metal oxides, mostly Zinc Oxide (ZnO, around 90% in mass percentage). These electronic devices can work better only if modifying their manufacturing process or by introducing other new additives, which can improve the electrical parameters of the ceramic semi-conductor material, especially on the non-linear dependence between the applied voltage and their response as resulting crossing current. This article is based mostly on an empirical process which can conduct to new semiconductor materials, by modifying some thermal parameters only. This article will describe the influence of the sintering temperature over the main electrical properties, for two newly conceived varsitor materials, only 2 and only 5 main dopants (additives).

Used for their excellent electrical behavior, as well as for their other good general properties, polymers are today applied mostly for the electrical insulation of underground BV/MV power line cables. Observed from the microscopic level, these dielectrics are not homogeneous. They present a mix of amorphous and crystalline volumes and the interface between these regions offers boudary junctions. This microscopic inhomogeneity detemines an increased space charge at the microscopic place. The existence of space charge causes an electric stress enhancement which may reduce the lifespan of the dielectric material. In this paper, partial discharges occurring in an air-filled gap between two closed high density polyethylene cavities are experimentally investigated. Measurements are performed at different temperatures, from 10°C up to 90°C and for different relative humidity ratios, from 20 up to 70%. The influence of these environmental parameters on PDIV, PD phase distribution and occurance numbers is clealy described.

All SF 6 based insulated systems are, today, the most advanced technical solution applied for HV or even MV devices, such as circuit-breakers and surge arresters. Capsulated SF 6 equipment, unlike opem one, are submitted to various hidden faults which are fully revealed only when all the existing piece of equipment is completely or partially destroyed. This simple gas is widely used due to a lot of excellent insulating properties. These properties are clearly depending on a lot of known variables, one of them is electrodes' shape, their material, and, also, the roughness of their electrodes, too. This paper presents a synthesis of this new dependence, combined with some experimental results. This simple study could be applied by both producers and users of this piece of equipment, as well as for their design.

Metal Oxide Varistors are, as electrical materials, composite ceramics, behaving like n - semiconductors, based on a poly-crystalline and complex physical and chemical structure. The application domain of these state of the art power electronic devices is mostly the overvoltage protection equipment (designed for every voltage level), based on some major advantages such as: a very high level of non-linearity between the resulting crossing current and the applied voltage characteristic, a high energy adsorption capacity and an excellent rapid response time, which make them suitable for protecting any other sensible electronic devices and pieces of circuits. This paper describes a new electronic material and some manufacturing technology issues of a Metal Oxide Varistor, based on some new mixtures of oxides used to obtain a new ceramic material with higher non-linear electric properties. The two dopant oxides taken in consideration are Sb 2 O 3 and Co 3 O 4 as additives. All measurements of the electrical behavior were carried out in relation with a classic 5 dopants material (other three + these two ones).

This paper quantitatively analyses magnetic levitation systems based on the integration of both permanent and DC electromagnets as the magnetic field sources. Such hybrid devices offer the advantages of high lift force to magnet weight ratio and very low power losses in its winding. The evaluation over a particular configuration is made both analytical and numerical reaching the optimal geometry for the hybrid magnet. Dynamical features of these systems are also treated, getting basics design criteria for the main magnetic field source. The results are compared with the solution of a small experimental model to verify its feasibility. All process is digitally controlled by using a standard PC and an adequate software.

This paper presents a laboratory method and an original control solution used in order to compute the influence of High Voltage Lines and Equipment on Low Voltage ones at 20 kV. All voltage lines taken in consideration could be either regular 400/230 V AC supply lines or even classic telecommunication lines belonging to the HV power station or to other TC companies. High voltage overhead lines are parallel or crossed in the proximity of low voltage lines, so, they could produce strong electric/magnetic fields or resistive modifications on the low voltage facilities. These influences can induce interferences and could cause fatal injuries to humans operating on low voltage equipment (even on domestic appliances) or great damages to all electronic equipment (IT, TV, TC, domestic). Our goal is to present, first of all, an analytic method used to assess the values of some parameters like the capacitive current, the capacitive voltage, the psofometrical voltage, the longitudinal induced voltage as well as the resistive voltage component. This laboratory equipment could be used for teaching purposes and for studies and recommendations demanded for designing electrical lines. Conceived for industrial use, it was already tested in the university, as didactic tool. On the second part of our paper, we will describe the architecture of that system, both as hardware, as well as from the software applied.

The anisotropy of the magnetic materials is an important parameter in many cases, especially in modern applications, like sensors or drives. This paper proposes a new approach to the study of the behavior of the intrinsic and extrinsic properties of these materials depending of the orientation of the sample in a magnetic field. By controlling a Vibrating sample magnetometer (VSM), it could be possible to obtain a hysteresis loop for various magnetization angles. The study was made mostly for tape recording media samples but it could be generalized to all magnetic materials on the market. The main advantage of this study is the possibility of digitally control on the VSM, which made this approach more flexible, fast and accurate.