Pavel Prosr - Academia.edu (original) (raw)

Papers by Pavel Prosr

The on-line monitoring is ever more frequent at diagnostics of machines, which have a strategic i... more The on-line monitoring is ever more frequent at diagnostics of machines, which have a strategic im-portance or their breakdown would means a big financial losses. The paper is focused on the theory of moni-toring systems constructions. Individual steps of realization are described -the selection of methods, data ac-quisition, diagnosed machine and measuring system connection. The selection of watched parameters suitable for diagnostic investigation is approximated on power transformers on-line monitoring. Streszczenie: Tak zwany monitoring on-line (cigły) maszyn o strategicznym znaczeniu lub takich, których awaria spowodowałaby znaczne straty ekonomiczne jest coraz powszechniej stosowany w diagnostyce tego typu maszyn. Niniejszy artykuł koncentruje si na teorii konstrukcji systemów monitorowania. Opisano poszczególne kroki projektowania i realizacji systemów monitoringu – wybór właciwych metod monitoringu, sposoby rejestracji i archiwizacji danych, sposoby sprzgania systemu monitori...

2016 Diagnostic of Electrical Machines and Insulating Systems in Electrical Engineering (DEMISEE), 2016

2015 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), 2015

The main objective of the paper is to describe the experience with newly developed monitoring sys... more The main objective of the paper is to describe the experience with newly developed monitoring system for transformers with oil-paper insulation system. From the view of operation reliability, it is necessary for operator s to provide a monitoring of transformer's failure free operation. The application of monitoring system enables to warn ti mely of the rising failure and also decrease of degradation of single subsystems of machine. When failure is detected, it is important to support this detection by other measurements tha t would lead to exact determination of the failure. SFRA analysis (Sweep Frequency Response Analysis) is such additional method in our monitoring.

2015 16th International Scientific Conference on Electric Power Engineering (EPE), 2015

Conference Record of the 2006 IEEE International Symposium on Electrical Insulation, 2006

Monitoring of the properties and applicability of highvoltage insulating systems containing epoxy... more Monitoring of the properties and applicability of highvoltage insulating systems containing epoxy resins require knowledge of curing degree of these resins. This curing degree is considered to be the key parameter for quality of materials used for these systems. Application of Differential Thermal Analysis (DTA) for evaluation of curing degree of three-component composite materials (glass fabric, reconstructed mica, and epoxy resin) is presented in the article. Used analysis enables to observe characteristic structural parameter -the concentration of reaction-able particles in organic component of this material. In our investigation, concept of curing reactions courses was obtained as well as details for determination of optimal curing time of material. These conclusions have been verified with the other methods such as Thermomechanical Analysis (TMA) or loss factor and permitivity determination. Based upon these results it is obvious, that the conclusions correspond to one another.

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2011

ABSTRACT Electrical technology diagnostics is a branch of science examining the actual state of e... more ABSTRACT Electrical technology diagnostics is a branch of science examining the actual state of electrical machinery under the operation when using two basic accesses. The first and older one is an “off-line diagnostics”. It means a device or an appliance subjected to diagnostic process need to be for example disconnected from circuit, turned off or stopped. An on-line diagnostics — diagnosing a device during its operation is the second access, nowadays more and more developed. Both diagnostics require detailed knowledge of physical processes taking place in diagnosed materials, devices etc., hence it is necessary to monitor the trends of specific parameters in time. This knowledge is mainly needed in the case of newly developed material application. A mathematical model is designed to describe observed physical processes according to the measured parameters in the diagnostic system. The paper presents results of long-term experiment dealing mainly with thermal and voltage ageing of electrical insulating materials. Both two and three component dielectrics are considered. Study is searching the correlation between ageing of the materials samples and ageing of the whole electrical devices. Tested samples of two and three component dielectric materials were subjected to the long-term laboratory ageing. The test samples were treated by high temperature, by increased voltage and cycled humidity. Different sets of samples were subjected to each of mentioned ageing factors. Ageing characteristics were calculated from different monitored parameters for each ageing factor. Important electrical parameters such as dissipation factor and resistivity vs. ageing time of aged materials are presented. Correlation between ageing characteristics of the same material and different ageing factors has been searched.

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2011

ABSTRACT An influence of thermal and voltage treatments on properties of high-temperature electri... more ABSTRACT An influence of thermal and voltage treatments on properties of high-temperature electrical insulating material based on mica and silicone binder was analyzed. Tested material is intended for an operation at extremely high temperatures along with electric field stress. The main aim was to describe the high temperature and electric field influence on the material inner structure. Thermal treatment was simulated by unrepeated thermal stress of 320 °C for the time of 500 hours. The material was also exposed to electric field intensities ranging from 9.6 to 15.9 kV/mm for times ranging from 7 to 280 hours. The samples were analyzed via Fourier Transform Infrared Spectroscopy, using the Attenuated Total Reflectance (FT-IR ATR) technique, and also via Microscopic Analysis. According to the measurement, accelerated thermal treatment has no significant effect on the inner structure. On the contrary, voltage treatment causes expressive degradation of the material.

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2011

ABSTRACT The stator wedge supporting material is used for diagnosing the state of the main insula... more ABSTRACT The stator wedge supporting material is used for diagnosing the state of the main insulation in rotating machines. The stator wedge is placed in a stator slot, and the material is aged using the same degradation conditions experienced by the bar winding insulating system itself. The possibility of easy replacement of the supporting material without causing any damage to the whole insulating system during device shutoff is a major advantage of this approach. The samples were tested with differential scanning calorimetry (DSC) and were prepared from isolated bars of a real hydroelectric generator (after 57,984 operation hours). The bar insulating system material (glass-mica-based) and the stator wedge material (laminated glass-fabric and laminated cellulose paper (paper-phenolic laminates) were tested. Additional laboratory thermal aging of the samples from both the bar winding insulating system and the supporting material was conducted to verify the suitability of the DSC method. Based on previous experience and on the thermal class of the insulating system (F − 155 °C), the aging temperature was set to 180 °C. Enthalpies were measured after 52, 70, 100 and 200 hours of aging. The samples from three bars (phase, zero and changed bar) were analyzed. Powdered samples from compacted bar insulation and stator wedge material were measured using DSC in a pure air atmosphere. The area of the first thermal oxidative peak (enthalpy) was evaluated. The experiment showed good agreement with the enthalpy results for the insulating system and the supporting material.

2007 Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, 2007

ABSTRACT The behavior of the oil-paper insulating systems of transformers is primary determined b... more ABSTRACT The behavior of the oil-paper insulating systems of transformers is primary determined by paper and oil basic properties. Recent studies are concerned to study of using synthetic oils instead of traditionally used petroleum based oils. This study monitors the influence of oil type on the final insulating system properties. The main degradation factor -temperature -is respected and properties under thermal stress are studied considering the degradation knowledge importance. The thermal analyses as well as the phenomenological test methods were used to perform the test results.

2014 IEEE 18th International Conference on Dielectric Liquids (ICDL), 2014

Conference Record of the 2006 IEEE International Symposium on Electrical Insulation, 2006

A condition of oil-paper insulating system is principal diagnostic indicator for failure-free ope... more A condition of oil-paper insulating system is principal diagnostic indicator for failure-free operation of power transformers. This insulating system is thought to be one of the key components of the whole machine. During the operation of the transformer ageing of the insulating system appears, which may cause changes of its important electrical and mechanical properties. Many factors work simultaneously on

2006 IEEE Conference on Electrical Insulation and Dielectric Phenomena, 2006

2008 IEEE International Conference on Dielectric Liquids, 2008

Power transformers are inconsiderable group of the electrical appliances with two components insu... more Power transformers are inconsiderable group of the electrical appliances with two components insulation system. One of the components - liquid insulating medium plays two roles- insulating and cooling. It can be mineral as well as synthetic based liquid. Second component is an organic based solid insulation usually of cellulose character. Organic materials of this structure are sensitive to an operational

2008 IEEE International Conference on Dielectric Liquids, 2008

ABSTRACT Insulating system of power transformers is mostly composed of two basic components: insu... more ABSTRACT Insulating system of power transformers is mostly composed of two basic components: insulation oil and cellulose paper (oil-paper system). These components are of an organic nature and thatpsilas why they become very sensitive to operation degradation conditions (temperature, oxidation, moisture etc.). Aging of these components can endanger the failure free operation of the transformers. The main objective of the paper was to analyze the aging process of liquid part of oil-paper insulation system by selected structural analyses. Three petroleum and three synthetic based insulation oils were chosen for the purpose of this experiment. The commercially available cellulose paper formed the solid part of the insulation. All insulation systems were exposed to accelerated thermal aging at increased temperature of 90 degC for the time range of 50 - 3000 hours. The degradation of oils inner structure was analyzed by Fourier transform infrared spectroscopy (specifically by Attenuated Total Reflectance technique). The analysis of insulation oil behaviour during thermal decomposition was the other aim of our experiment. Thermogravimetry and derivative thermogravimetry were applied as the proper tools for this purpose. Results of structural analyses clarify very well the differences between the behaviour of mineral and synthetic insulation liquids at common temperatures as well as during the thermal decomposition.

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2012

ABSTRACT There is difficult to imagine modern manufacturing of electrical devices without compone... more ABSTRACT There is difficult to imagine modern manufacturing of electrical devices without components containing (mainly for technological reasons) organic substances. This fact is mainly concerned to composite materials, in which the bond component is made of organic substance. Most of the electro-insulating materials used in common applications are composite materials. The possibility of the determination of dielectric properties of these systems is a problem of theoretical as well as practical importance. The paper is focused on thermal aging and accompanied dielectric spectroscopy diagnostics of two mainly used materials, which are utilized as a part of insulation system of electrical devices. The first tested specimen was mica composite material based on glass fibre and epoxy resin and the second one was two component composite based on epoxy resin as well. The specimens were tested under laboratory conditions. The materials were thermally aged and the changes of its physical and chemical properties were measured and evaluated. For accelerating the aging process different temperature values (170-200°C) were chosen. The aging time was determined for each temperature value. Specimens of tested material were performed and cured as flat plate 100×100 mm. The measuring of these specimens was carrying out in frequency domain from 200 Hz to 2MHz at special electrode test setup. For comparing the aging process of the investigated material the trends of measured parameters were studied and described in dependence on exposure time, temperature and applied frequency during measurement.

Proceedings of the 2014 15th International Scientific Conference on Electric Power Engineering (EPE), 2014

2013 IEEE International Conference on Solid Dielectrics (ICSD), 2013

ABSTRACT The main objective of this paper is to investigate the possibility of application of Fou... more ABSTRACT The main objective of this paper is to investigate the possibility of application of Fourier transform infrared spectroscopy and method of discriminant analysis for classification of a solid dielectric. Classification method was determined by applying accelerated thermal aging on glass-mica-based insulating system material. Based on previous experience and on the thermal class of the insulating system, the aging temperature was set to 170 °C. Infrared spectra were measured after 192, 384, and 600 hours of aging using technique of Attenuated Total Reflectance in the middle area of the infrared electromagnetic spectrum (4000-600 cm-1). Regarding the results, it is possible to state that the method of discriminant analysis in connection with Fourier transform infrared spectroscopy can be regarded as a proper diagnostic indicator of aging for material of insulating systems.

ABSTRACT Insulation liquids are mainly used in oil filled transformers for their cooling and insu... more ABSTRACT Insulation liquids are mainly used in oil filled transformers for their cooling and insulating properties. Besides a testing of electrical properties, there is also important to monitor oxidation stability and activation energy as the factors which can decide on an application possibility of the insulating liquid. The main aim of this paper is to describe the influence of temperature aging on the oxidation stability and activation energy of tested insulating liquids (common petroleum based product and dioctyladipate - di(2-ethylhexyl) ester of adipic acid - synthetic based liquid). Both liquids were exposed to a longterm thermal aging at the temperature of 90degC for 3000 hours. A thermogravimetry was applied to determine the activation energy, oxidation stability tests were performed by differential scanning calorimetry.

ABSTRACT Power transformer service availability is influenced by a condition of insulating and co... more ABSTRACT Power transformer service availability is influenced by a condition of insulating and cooling medium - by transformer oil properties. The transformer is subjected to many untypical situations arising casually or due to changed operation conditions. Between the casual phenomena belongs e.g. an unbalanced loading, which causes phases overload etc. These situations reflect on the properties of cooling medium. Parameters such as an excessive formation of gasses in transformer oil, an increase of water presence in the oil or changes of temperature distribution along the winding of transformer can be changed during the operation. Monitoring of these changes is performed in our experimental department, which was developed directly for this purpose. Tested transformer is equipped with sensors for mentioned parameters monitoring. Information obtained from laboratory testing of the experimental transformer will be useful for assessment of processes proceeding in common operation of these devices.