Quality assessment during dc motor manufacturing should be accomplished by quality controls in order to detect the different fault conditions associated to the components included in the machine. However, some defects can be produced by the automatic manufacturing process during the assembly of the individual components. Among others, inter-turns short-circuit, turn to earth short-circuit and open-winding can result from the rotor insertion inside the stator. The main problem with these kind of faults is that the motor can operate but there is a high probability of motor breakdown in the near future. In this work, the above fault conditions are analyzed and an electromagnetic field and thermal monitoring method is proposed

In the last decade, the emergence of leaf disease caused by the fungus Mycosphaerella sp. is jeopardizing the development of some species of the genus Eucalyptus at its juvenile life stage. The development of forest species for energy purposes, namely to generate biomass in shorter periods, must take into account this circumstance at the time of measuring the energy density generated by these species.

This paper defines a method which relates the measure of the severity of the disease with the energy lost per Ha. First, it has been characterized from the energy point of view, thus, it has quantified the calorific value of the biomass of Eucalyptus globulus decomposing it in their respective fractions at certain moisture. Then, depending on the degree of severity of the disease, it has been estimated the amount of dry biomass per tree at the age of 27 months and crossing it with the calorific values it has been determined the energy loss per unit of area according to the overall damage index.

Finally, a brief economic analysis considering the consequences of this disease in a stand of Eucalyptus globulus for energy production, has been performed.

In this work a new design for reversible air-air heat pumps is proposed. This design is based on the inversion of the air flow on the ducts, instead of the refrigerant changeover, as is proposed by ASHRAE. Thanks to this modification it is possible to use any conventional air-air refrigeration machine for air conditioning as a reversible heat pump.

The new design is more efficient, especially when a great air quality it is required in the building and therefore a larger amount of outdoor air it is used. Compared with traditional designs it also increases the efficiency as the outdoor temperatures become more extreme. This improvement will make it possible to use heat pumps, with acceptable performances, in more rigorous climates than those in which they are used today.

Nowadays, energy efficiency is a hot topic in a very demanding environment. In this way, improvements in lighting applications, which is a significant point of energy consumption, could be very much welcomed. Electronic ballast may serve to this goal since they are focused on achieving energy savings, reduction in the utility line harmonic content and reactive power, as well as on implementing dimming control and some other parameter of interest in lighting applications. On the other hand, power quality problems are very common in our power system and any new electric device should be designed taking into account these events. One of the typical problems in electrical distribution systems are voltage sags. These have a great incidence on the electrical equipment connected to the network in the same area. The sags cause more damages than the rest of disturbances because these have a greater frequency of occurrence. In this work, the effects of voltage sags on several 150-W high- pressure sodium lamps combined with two different types of electronic ballast have been studied. One of the ballasts supplies the required voltage to minimize the reactive component in the resonant inverter, while the other regulates the power supplied by the utility line to be constant in long term, the resonant inverter being also in open loop at constant switching frequency providing the short term stability. The results of these electronic ballasts will be compared with those obtained with the traditional electromagnetic ballast. The influence of the lamp age will be also considered in the approach. The final goal of this study is to improve the performance of the ballast prototypes under voltage sags.

The IEC has standards covering both a flickermeter and a flicker definition. These documents have been adopted in Europe by the CENELEC as EN norms. The limits of the severity of flicker caused by voltage fluctuations is defined in Europe by the standard CENELEC EN 50160. Under normal operating conditions, flicker level measured according to IEC 61000-4-15 will not exceed the long term severity Plt=1 during 95% of the time in one week. This threshold was originally established considering that a lamp with tungsten coiled coil filament of 60 W and 230 V that is gas-filled produces a flicker perceivable by 50% of the population when it is supplied with a voltage that verifies Plt=1. Other light sources like fluorescent lamps and discharge lamps with ballasts exhibit a different behavior under the same supply conditions. This means that the flickermeter should be different for each type of illumination technique in order to provide accurate information about flicker phenomena. At the same time, lamp age also plays an important role in flicker generation. The above are the main objections given for not adopting the IEC flickermeter in countries as USA. In this research work, a test system and a methodology able to measure the optical fluctuation produced by different types of lamps and ballast is presented. This experimental platform allows to obtain a correlation between voltage flicker levels and optical flicker perception. It can be considered the first step in the definition of new lamp models. This work also shows that age lamp has a significant correlation with flicker generation.

The limits of the severity of flicker caused by voltage fluctuations is defined in Europe by the standard CENELEC EN 50160. Under normal operating conditions, flicker level will not exceed the long term severity Plt=1 during 95% of the time in one week. This threshold was originally established considering that a lamp with tungsten coiled coil filament of 60 W and 230 V that is gas-filled produces a flicker perceivable by 50% of the population when it is supplied with a voltage that verifies Plt=1. Other light sources like fluorescent lamps and discharge lamps with ballasts exhibit a different behavior under the same supply conditions. This means that the flicker meter should be different for each type of illumination technique ir order to provide accurate information about flicker phenomena. At the same time, lamp age also plays an important role in flicker generation. In this research work, a test system and a methodology able to measure the optical fluctuation produced by different types of lamps and ballast is presented. This experimental platform allows to obtain a correlation between voltage flicker levels and optical flicker perception. It can be considered the first step in the definition of new lamp models. This work also shows that age lamp has a significant correlation with flicker generation.

Quality assessment during dc motor manufacturing should be accomplished by quality controls in order to detect the different fault conditions associated to the components included in the machine. However, some defects can be produced by the automatic manufacturing process during the assembly of the individual components. Among others, inter-turns short-circuit, turn to earth short-circuit and open-winding can result from the rotor insertion inside the stator. The main problem with these kind of faults is that the motor can operate but there is a high probability of motor breakdown in the near future.

In this work, the above fault conditions are analyzed and an electromagnetic field and thermal monitoring method is proposed.

The European standard CENELEC EN 50160 establishes that the severity of flicker caused by voltage fluctuations, under normal operating conditions, will not exceed the long term severity Pu = 1 during 95% of the time in one week. This threshold was originally established considering that a lamp with tungsten coiled coil filament of 60 W and 230 V that is gas- filled produces a flicker perceivable by 50% of the population when it is supplied with a voltage that verifies Pu = 1. Other light sources like fluorescent lamps and discharge lamps with ballasts exhibit a different behavior under the same supply conditions. This means that the flickermeter should be different for each type of illumination technique. A test system and a methodology able to measure the optical fluctuation produced by different types of lamps is presented. This experimental platform allows to obtain a correlation between voltage flicker levels and optical flicker perception. It can be considered the first step in the definition of new lamp models and the specification for new electronic ballast design.

Quality assessment during dc motor manufacturing should be accomplished by quality controls in order to detect the different fault conditions associated to the components included in the machine. However, some defects can be produced by the automatic manufacturing process during the assembly of the individual components. Among others, inter-turns short-circuit, turn to earth short-circuit and open-winding can result from the rotor insertion inside the stator. The main problem with these kind of faults is that the motor can operate but there is a high probability of motor breakdown in the near future.

In this work, the above fault conditions are analyzed and an electromagnetic field and thermal monitoring method is proposed

At the present time the generation expansion planning (GEP) has become a problem very difficult to solve for multiple reasons: many objectives, high uncertainties, very great planning horizon, etc. Its resolution by means of the exact traditional techniques, in numerous occasions, is not viable by the excessive time that is needed. For that reason, technical modern that allow the resolution in smaller time and with smaller accuracy in the solution are applied. Most of the approximate techniques are included inside a wider concept that is denominated Artificial Intelligence. In this article the more promising techniques of IA are studied indicating their applications in the PEG as well as their advantages and disadvantages

In air conditioning facilities most of the energy consumption corresponds to the thermal production, this being heat and cold. It depends on many factors, one of the most important in the use of more efficient devices (boilers, chillers and heat pumps)for supply thermal energy. In this work the efficiency of the reversible waterwater heat pumps is analyzed, proposing a new better design that optimizes the nergy consumptiom. This improvement hardly requires modifications at manufacturing, therefore, it could be easily developed by manufacturers.

Voltage sags are nowadays the first power quality problem in the distribution power system. This work evaluates the real implementation of a voltage sag characterization based on a DSP platform. Several classification methods for voltage sags have been presented in the literature. Here the Bollen’s classification is tested. Automation of sag assessment is desirable because manual analysis may be quite difficult.Thus, the fuzzy logic technique is chosen for this aim. This logic system generalizes the classical two-valued logic for reasoning under uncertainty. The fuzzy algorithm was first tested by simulation and then it was translated into C code in order to be implemented in a DSP based measurement platform, obtaining a satisfactory result.

In this work a power characterization of adult stages of the species Eucalyptus globulus and Eucalyptus nitens has been made.

The study has been made in six different plantations in Cantabria (North coast of Spain), located at a latitude 43º28’N, and a longitude 3º48’W. The region has approximately 30,000 Ha dedicated to the growth of Eucalyptus. After the collection of samples they were weighed, analyzed and burned, resulting a mean net calorific value of 17,384 kJ/kg and 17,927 kJ/kg for the E. globulus and E. nitens, respectively.

Finally, the economic and environmental consequences that the crop of these species would suppose for the region of Cantabria were analyzed.

This research work is devoted to the development of an electrical and mathematical model able to simulate the static and transient phenomena in a small power polymer electrolyte membrane fuel cell (PEM) system. At present, there are different electrochemical models available to capture the steady state behavior by estimating the equilibrium voltage for a particular set of operating conditions. However, it is difficult to find models capable of describing transient phenomena. Dynamic models are very interesting from a practical point of view when the loads exhibit large variations. Some examples are powertrains of land-based vehicles or submarines. In that cases, the output power from the fuel cell shows large variations during acceleration and deceleration.

The electric generation produces damages (externalities or environmental costs) that are not contemplated in the costs of this activity. A way to include these damages in the cost is based on the emission rights. In these instruments the total amount of allowed contamination is fixed. It is assigned to the polluting agents by means of emission permissions, creating a market of these, in which the agents can exchange them based on their interests. In 2005, Spain undertook the National Plan of Allocation of Emission Rights 2005-2007 (PNA 2005-2007). This plan has established an emission limit to the electrical sector and it has been translated in the allocation of emission rights. If this emissions limit is surpassed they must acquire rights that cover the exceeded. Thus, the companies must reduce their emissions without increasing their costs. What mix of generation is have to be implement in order to minimize the emissions, avoiding to charge the emission rights in the total generation cost?. If it is impossible to cover the demand without this extra cost, how to diminish it? These questions can be responded using optimization methods.

When a power transformer is energized there is an important transient inrush of current that it is necessary in order to establish the magnetic field of the transformer. Some power transformers exhibit peak current demand up to eight or ten times the nominal value. In addition, during the first cicles high values of the homopolar components of current are also requested by the transformer. If the power transformer is placed in a substation that works as a common coupling point
for distributed generation facilities some specific power quality problems can be found. This paper analyzes the problem from a general point of view considering not only the theoretical approach but also the results obtained in a real case including two 180 MVA power transformer and a 120 MW distributed generation

It is well known that the power factor is the relation between active power and apparent power. Moreover, the square of the power factor represents the relationship between the minimum power loss and the present power loss. This paper deal with the decomposition of the latter ratio into three factors; the first related to the current imbalance, the second to the current distortion and third to the reactive power consumption. Once the contribution of each factor is known, it is posible to determine which disturbance produces the greatest losses. This concept is applied to a three phase-four wire system, with and without neutral resistance.

The utilization of Clark’s transformation in the estimation of the power system frequency provides more robustness to the classical single-phase methods. One of the advantages of this technique is that extract the frequency information contained in the three-phase system. This is particularly important when asymmetric sag generates a zero voltage in one of the three phases.

In this paper the authors analyze different alternatives to provide energy utilities to a hospital center with cogeneration systems with diesel engines and gas turbines. The study considers several power sizes and control strategies, so it shows the influence of these parameters, showing that in this case the options with diesel engines are more efficient than the equivalent ones with gas turbines.

In this work, the authors analyze productive, power, environmental and economic aspects of the forest biomass in the north of Spain. All these points will determine the future development of this power resource, making special reference to the case of the province of Cantabria.

Currently, there are two energy meters types installed: electromechanicals and electronics. The first ones are still the most frequent. However, new facilities tend to use electronics energy meters based on solid-state technology. Electromechanicals devices present characteristics already well known that allows us to measure only energy consumption. However, now the rules that manage the energy supply are totally new, there is a competitive electricity market. This way, detailed information on the energy consumption of each client is needed. In this point, electronic meters seem to be the best option to face the new challenges. This study will review the operating principles of solid-state energy meters. The behavior of some three phases models under nonsinusoidal conditions is studied. Experimental setup and test methodology are discussed as well.

Frequency measurement is an important issue in electrical engineering. Electric power systems have become increasing complex over the last decade. The use of distributed generation, the connection of non-linear loads and the presence of unexpected system faults are the main causes of frequency variations. In addition, power quality includes frequency as an important index. From a hardware instrumentation point of view, frequency measurement has different requirements:

i.) Large power systems have slow frequency variation due to the high inertia of the overall network. This kind of problem requires frequency measuring methods capable of detecting small and also slow frequency variations.
ii.) Small power systems can have frequency variation due to their reduced short-circuit power capacity. This type of problem requires fast methods with the capacity to detect large frequency variations.

There are different groups of methods intended for frequency measurement. The methods can be compared in terms of computation and dynamic response, especially when the main voltage is disturbed.

This research work focuses on frequency measurement under non-sinusoidal conditions. The paper studies the behaviour of a modified version of Sezi’s method and its hardware implementation using a microcontroller. This system can be used for frequency measurement or as a synchronized sampling source in harmonic measurement (e.g. EN 61000-4-7)

The fast time response of the system enables it to be used in almost all kinds of application: small and slow frequency variations; frequency triggering in power system protection and power quality index characterisation.

These days, the ability to make brilliant presentations is increasingly valued. In the academic world, it is commonplace for each professor to elaborate his own materials. In the business world, however, a great deal of audiovisual documentation is generated which certain employees are then required to present, either to groups of clients or to university groups. When a presentation is imposed on speakers in this way, they must have the skill to defend a tool designed by someone else with the same conviction as they would defend their own work. In the professional Presentation Test, the student is immersed in this situation.
The students of Advanced Electric Circuits of the current study plan of the Industrial Engineering and Telecommunications School of the University of Cantabria have been informed that this test will be offered to the two students with the highest and second-highest marks. If either or both of them renounced it, it will be offered to the student with the next highest mark, and so on.

The aims of this test are:

– To provide training for future oral presentations.
– To develop skills in use of external aids.
– To promote the vocation for teaching.
– To encourage the students to improve their academic record.

Before the test, each student must select the three topics s/he prefers. One of these, chosen by the professor, will be the subject of the presentation. There will be a period of between five and ten days between the selection of the topics and the test. The test regulations are as follows:

– The student is handed the material which s/he will use for a presentation in public lasting thirty minutes.
– Once the documentation receives the material, s/he has thirty minutes to prepare the presentation, using any bibliographical aids that s/he considers appropriate.
– Once the presentation is finished, the professor may discuss it with the student for a maximum time of 15 minutes.

The examining board will be made up of the teachers of the subject or, alternatively, teachers from the field of Electrical Engineering. Once the test is finished, after the deliberation of its members, the board will inform the student of his mark, comment on any errors and make any suggestions they deem appropriate.

En este trabajo describiremos los sistemas de arranque más empleados con los motores eléctricos monofásicos que accionan los compresores herméticos de los pequeños equipos de aire acondicionado y refrigeración, caracterizando su funcionamiento según configuración de arranque, y su ámbito de aplicación óptimo. Palabras clave: Ciclo frigorífico, arranque de motor monofásico, compresores herméticos.

Power Quality assessment in distribution networks requires distributed measurements in order to verify the PQ state of the art. This process cannot simply be considered as an extension of a measurement at a given point because several variables need to be considered: number of PQM; election of optimal measurement location; synchronisation of instrumentation and management of captured data.

This work focuses on the problems related with the simultaneous utilisation of different flickermeters in large electric networks.

From a classical instrumentation point of view, several flickermeters from different customers are tested in the laboratory in order to determine the differences in the accuracy of the results. Both Pst and Plt are statistical parameters calculated using a large number of samples of the instantaneous flicker level IFL . The number of captured samples can vary from one instrument to another, so different flickermeters provide different values.

The European standard CENELEC EN 50160 establishes that the severity of flicker caused by voltage fluctuations, under normal operating conditions, will not exceed the long term severity Plt=1 during 95% of the time in one week. This threshold was originally established considering that a lamp with tungsten filament of 60 W and 240 V, produces a flicker perceivable by 50% of the population when it is supplied with a voltage that verifies Plt=1. This work makes an analysis of this threshold, establishing as hypothesis the fact that incandescent lamps have little use nowadays, specially in industrial and commercial environments. In order to make a revision of the current thresholds, we have proposed an electro-optical equipment and the associated methodology. The device simulates the behavior of the eye plus human brain set, avoiding large clinical experiments. A methodology is also proposed in order to characterize the perceptibility threshold of a generic lamp. Finally, the proposed instrumentation and methodology is applied to two types of lamps: incandescent and fluorescent.