Αναλυτικός πίνακας δημοσιεύσεων
ΚωνσταντίνοςΔ. Χαλεβίδης
1.Δημοσιεύσεις σε έγκριτα περιοδικά (μεimpactfactor)
1.1.Halevidis C.D., Anagnostatos S.D., Polykrati A.D., Koufakis E.I., Bourkas P.D., Proposal of a protection method against probable consequences to humans and the environment from short-circuit or abruption of a low-voltage distribution line conductor, Generation, Transmission & Distribution, IET, 4 (2010) 793-800.
Περίληψη: The maximum length of a low voltage distribution line (400 V) is determined by the transformer power, the type and cross section of the conductors as well as the nominal current of the fuse. Meeting this requirement fulfills the neutralization condition. A low voltage distribution network bare conductor being abrupted can cause deadly electrocution to a person or start up a fire. Relative foresight is needed in altering the regulations, so as to exclude the fore mentioned consequences to humans and the environment. A protection method is comprised of a system utilizing the Global System for Mobile communications (GSM) placed on the last pole of each line which is activated when a line is cut off and powers down the circuit through means of an automatic circuit breaker installed upon the low voltage distribution panel.
Ετεροαναφορέςαπό:
1.1.1.Koustellis, J.D., Polykrati, A.D., Katsanis, J.S., Halaris, P.G., Bourkas, P.D., Protective measures against electrical hazards of consumer installations, (2011) Proceedings of the IASTED International Conference on Power and Energy SystemsEuroPES 2011, 277-279.
Impact factor περιοδικού: 1,307
1.2.Halevidis C.D., Anagnostatos S.D., Polykrati A.D., Koufakis E.I., Bourkas P.D., Abruption cross-section and bending change of ACSR energy lines in fire environment, Advances in Mechanical Engineering, (2010), doi: 10.1155/2010/291630
Περίληψη:An ACSR (Aluminum Conductors Steel Reinforced) power line, when it lies in a fire environment, can manifest a permanentelongation and change in bending, as when the conductors attain a temperature of over 500οC, a drastic fall of the mechanicalstrength of the steel core is caused. This work is a study about the conductor cross-section at the position of the abruption, in caseit occurs. This cross section appears to be approximately 62.5% of the original value. Subsequently, two approximative methods ofcalculating the bending change of overhead lines are shown.
Impact factor περιοδικού: 0,500
1.3.Proios A.N., Halevidis C.D., Koufakis E.I., Bourkas P.D., Magnetic-Field Measurements Near Two-Pole-Type Distribution Substations, Power Delivery, IEEE Transactions on, 26 (2011) 1137-1144.
Περίληψη:This paper presents the mean values of the resultant magnetic field in the low frequency range, which were recorded during spring and summer near two-pole-type distribution substations in urban areas. The mitigation of the magnetic field that was achieved after covering the LV fuse boxes with thin aluminum plates is also presented. The mean attenuation achieved is approximately 23% during spring and 18% during summer at the region of up to 30 cm from the substations and at a height of 1.0 m from the ground, at the measuring points near the LV fuse boxes. All the measured magnetic field values that were observed were lower in comparison with those specified as limits and introduced by ICNIRP.
Ετεροαναφορέςαπό:
1.3.1.Okun, O., Shevchenko, S., Korpinen, L., A comparison of magnetic fields inside and outside high-voltage urban 110-kv power substations with the exposure recommendations of the ukrainian regulatory authorities, Radiation Protection Dosimetry, 154 (2013), 417-429.
Impact factor περιοδικού: 1,657
1.4.Anagnostatos S.D., Halevidis C.D., Polykrati A.D., Koufakis E.I., Bourkas P.D., High-Voltage Lines in Fire Environment, Power Delivery, IEEE Transactions on, 26 (2011) 2053-2054.
Περίληψη:This work concerns the change in bending which can manifest in a high voltage line, when it lies in a fire environment. It is shown that in the case where ACSR conductors (Aluminum Conductors Steel Reinforced) attain a temperature of over 500 oC, a drastic fall of the steel core mechanical strength is caused, resulting in permanent elongation of the line which decreases drastically the clearance from the underlying vegetation.
Impact factor περιοδικού: 1,657
1.5.KoustellisJ.D., AnagnostatosS.D., HalevidisC.D., KaragrigoriouF.S., PolykratiA.D., BourkasP.D., Contactofheavyvehicleswithoverheadpowerlines, SafetyScience, 49 (2011) 951-955.
Περίληψη:Contact with overhead power lines is regarded worldwide as one of the leading causes of electrical fatalities. The analysis carried out in this paper refers to a real accident that occurred in Greece a few years ago, involving the contact of a heavy vehicle (concrete pump) with the medium voltage lines of the national distribution network. For a better understanding of the incident, a description of how the protection system of medium voltage distribution lines works when a fault occurs is given. Furthermore, emphasis has been laid on possible ways to avoid similar accidents in the future.
Ετεροαναφορέςαπό:
1.5.1.Chi C., Lin Y., Ikhwan M., Flow diagram analysis of electrical fatalities in construction industry Safety Science, 50 (2012) 1205-1214.
1.5.2.Bas, E., An integrated quality function deployment and capital budgeting methodology for occupational safety and health as a systems thinking approach: The case of the construction industry, Accident Analysis and Prevention, 68 (2014), 68, 42-56.
1.5.3.Gürcanli, G.E., Müngen, U., Analysis of construction accidents in Turkey and responsible parties, Industrial Health, 51 (2013), 581-595.
Impact factor περιοδικού: 1,672
1.6.Halevidis C.D., Wooden pole ladder network model development and verification using finite element analysis, European Transactions on Electrical Power, 23 (2013) 62-71. doi: 10.1002/etep.643.
Περίληψη: In this article, a new resistive ladder network, describing the electrical behavior of the wooden pole, cross arm, and their interconnection, is developed. The network is developed and verified using the results of the finite element analysis of the construction. Good agreement was achieved between the two analyses. In addition, several pole–cross arm topologies were studied, and the effect of the different elements on the total resistance of the construction was quantified. Characteristically, it was found that the use of a steel cross arm instead of a wooden one decreases drastically the total resistance. Also, the use of a steel cross arm brace can reduce the total resistance by up to 37.4%.
Impact factor περιοδικού: 0,631
1.7.Koufakis E.I., Halevidis C.D., Polykrati A.D., Tsarabaris P.T., Calculation of the Activation Energy of Oil-Paper Insulation in a Distribution Transformer, Electrical Insulation Magazine, 28 (2012) 52-58.
Περίληψη: Transformers are key points of power networks. Preventive diagnosis and maintenance of transformers are necessary in order to improve the reliability of power systems. An extensive research has led to the development of various methods used to diagnose the condition of their insulation. In some of these methods the activation energy of the insulating materials is the determinant factor. This paper primarily presents measurements of insulating resistance in distribution transformers, at various temperatures, and there after the calculations of the activation energy of their oil-paper insulating system. Observations and comments on the behavior of the transformer insulating system are made.
Ετεροαναφορέςαπό:
1.7.1.Baral, A; Chakravorti, S., Prediction of moisture present in cellulosic part of power transformer insulation using transfer function of modified debye model, Dielectrics and Electrical Insulation, IEEE Transactions on, 21 (2014) 1368-1375.
Impact factor περιοδικού: 1,61
1.8.Halevidis C.D., Bourkas P.D., Karagiannopoulos C.G., Thermal Effect of the Recloser Operation Cycle on Bare Overhead Conductors, Power Delivery, IEEE Transactions on, 27 (2012) 568-574.
Περίληψη:A new calculation method of the temperature rise generated from multiple (consecutive) short circuits, to which bare overhead conductors are subjected, is proposed in this paper. Multiple short circuits are common in medium-voltage lines protected by reclosers due to their operation cycle. The proposed method treats each short circuit as a separate event. In addition, the cooling between each short circuit is taken into account. The results of the proposed method are compared to the results given by the method of the IEC 60865-1 standard. The application of the proposed method results in greater temperature rises when the equivalent thermal current density is greater than a threshold. Furthermore, alterations to the recloser operation cycle are performed in order to investigate its effect on the generated temperature rise, namely, alterations to the reclosing interval between successive tripping operations and the ratio of fast to delayed trips. Finally, the proposed method was compared to an exact numerical solution of the heating process.
Ετεροαναφορέςαπό:
1.8.1.Wiecek, B., De Mey, G., Chatziathanasiou, V., Papagiannakis, A., Theodosoglou, I., Harmonic analysis of dynamic thermal problems in high voltage overhead transmission lines and buried cables, International Journal of Electrical Power and Energy Systems, 58 (2014), 199-205.
Impact factor περιοδικού: 1,657
1.9.Halevidis C.D., Koustellis J.D., Polykrati A.D., Bourkas P.D., Exposure of workers to ELF magnetic fields during the temperature-rise test of electrotechnical equipment, Measurement, 45 (2012) 1960-1965.
Περίληψη: In this paper, extremely low frequency (ELF) magnetic fields (MFs) were measured duringthe temperature-rise test of various electrotechnical equipment. The number of workers subjected to magnetic fields from the temperature-rise test is small; however, the exposure can be significant as the testing currents can be in the order of hundreds amperes. The resultant magnetic field during testing can exceed the ICNIRP limits for occupational exposure. The magnetic field exposure was recorded and statistical measures were extracted for three electrotechnical apparatus. It was found that the Time-Weighted Average exposure per unit current can reach 0.0598 lT/A. Additionally, in order to mitigate the exposure, a rule of thumb regarding safety distances has been proposed. It is shown that the use of this rule of thumb can reduce the magnetic field exposure.
Ετεροαναφορέςαπό:
1.9.1.Churlaud O., Hemette S., Liu Υ., Oger C., Yang X., PE 103: Création d’un outil d’aide à la mesure des champs magnétiques de basse fréquence, Project report, (2013).
Impact factorπεριοδικού: 1,526
1.10.Halevidis C.D.,Koufakis E.I.,Power Flow in PME Distribution Systems during an Open Neutral Condition, Power Systems, IEEE Transactions on,28 (2013) 1083-1092.
Περίληψη: The open neutral condition, in distribution networks, can cause significant damage to customer installations. Due to this, the continuity of the neutral conductor is important to the power utilities. In this paper, a power flow algorithm for three-phase four-wire distribution networks with protective multiple earthing (PME), during an open neutral condition, is presented. This algorithm is based on a modified backwards-forwards technique. Additionally, the return current flow is explicitly modeled. Results from three different distribution feeders with different load unbalance and topology are presented and discussed. Furthermore, the effects of the grounding resistances, the load model (constant admittance or constant power), and the neutral breakage point (abruption point) on the voltage levels, are investigated.
Impact factorπεριοδικού: 3,53
1.11.Koustellis J.D.,Halevidis C.D.,Polykrati A.D.,Bourkas P.D.,Analysis of a Fatal Electrical Injury due to Improper Switch Operation, Safety Science, 53 (2013) 226-232.
Περίληψη: Electrical accidents are significant causes of occupational fatalities in the world. The analysis carried out in this paper refers to a real accident that occurred in Greece during the repair work carried out on a medium voltage transformer of the Public Power Corporation (PPC). While attempting to restore the electrical power, the electrician climbed the pylon where the transformer was placed and tried to change the single pole fuse. The insulator of the phase broke, resulting in the release of the power distribution wire. The technician came into contact with the loose wire with his lower limb and suffered an electric shock. For a better understanding of the incident, a description of the distribution network is given. Furthermore, emphasis has been laid on possible ways to avoid similar accidents in the future.
Impact factor περιοδικού: 1,672
1.12.AnagnostatosS.D., Halevidis C.D., PolykratiA.D., BourkasP.D., KaragiannopoulosC.G., Examinationofthe 2006 blackoutinKefalloniaIsland, Greece, International Journal on Electrical Power and Energy Systems, 48 (2013) 122-127.
Περίληψη:The blackout on the Greek island of Kefallonia on January 24th 2006 was caused by the fall of 10 towers of the 150 kV power transmission network due to high winds and heavy snowfall. These extreme meteorological phenomena were unprecedented on the island and thus had not been taken into consideration by the Greek installation and maintenance regulations regarding these towers. Due to changes in meteorological conditions in recent years, the above regulations have to be revised so as to propose smaller distances between towers in new transmission lines and improvements to the existing lines to endure severe weather conditions when necessary. This paper provides a short description of the High Voltage (HV) network of the island of Kefallonia, the system conditions before and after the blackout, and identifies the causes of the blackout. In addition, the mechanical strength evaluation of the simple circuit towers (similar type to those that collapsed) is made under the stress of gale-force winds combined with the ice-coating of conductors. Finally, in order to avoid the repetition of such an outage, several methods are proposed.
Impactfactorπεριοδικού: 2,694
1.13.G. K. Soulinaris, C. D. Halevidis, A. D. Polykrati, P. D. Bourkas, Evaluation of the thermal stresses and dielectric phenomena in the investigation of the causes of wildfires involving distribution power lines, Electric Power Systems Research, 117 (2014) 76-83..
Περίληψη:In this paper, the thermal stresses and dielectric phenomena of distribution power lines are evaluated in order to ascertain whether the line was the cause or the victim of a wildfire. The thermal stresses, to which distribution overhead lines are subjected, due to the line current, short-circuits, or due to the wildfire are calculated. Furthermore, the various dielectric phenomena of distribution lines are presented and their ability to start a wildfire is examined. Moreover, experiments concerning aspects of wildfire forensics were undertaken. During these experiments, the ability of ejected incandescent aluminum molten particles to cause a wildfire was investigated. Finally, a case study of a real incident, in which a medium voltage overhead line was blamed for a wildfire, is examined. The aim of this work is to assist in the formation of guidelines which can be used in the investigation of the causes of a wildfire involving distribution power lines.
Impactfactorπεριοδικού: 1,595
2.Δημοσιεύσεις σε έγκριτα περιοδικά(χωρίςimpactfactor)
2.1.ΧαλεβίδηςΚ.Δ., ΚουφάκηςE.I., ΜπούρκαςΠ.Δ., Σύστημα προστασίας σε γραμμές ΧΤ, Σύγχρονη Τεχνική Επιθεώρηση, 242 (2012) 18-23.
Περίληψη:Σε αυτήν την εργασία διερευνάται η επίδραση της καταστάσεως του ανοικτού ουδετέρου σεγραμμές διανομής ΧΤ με ουδετερογείωση και άμεση γείωση (συστήματα γειώσεως TN-C-S PMEκαι ΤΤ αντίστοιχα κατά IEC). Μελετάται η επίδραση της ασυμμετρίας της φόρτισης, και πιοσυγκεκριμένα του συντελεστή ισχύος των φορτίων, της σχετικής φόρτισης των φάσεων, τηςαντίστασης γειώσεως κτλ. Από τα αποτελέσματα της θεωρητικής ανάλυσης και της προσομοίωσηςτων μεταβατικών φαινομένων κατά το άνοιγμα του ουδετέρου, διαπιστώνεται πως η τάσηουδετέρου-γης μπορεί να πάρει επικίνδυνες τιμές ενώ τα φορτία υποβάλλονται σε υποτάσεις ήυπερτάσεις. Στην εργασία αυτή προτείνεται μια μέθοδος προστασίας στην εγκατάσταση τουκαταναλωτή η οποία προστατεύει και κατά την αποκοπή αγωγού (φάσεως ή ουδετέρου) τουδικτύου, απομονώνοντας την εν λόγω εγκατάσταση από το δίκτυο.
3.Άρθρασεπρακτικάδιεθνώνσυνεδρίων με κριτές
3.1.Halevidis C.D., Anagnostatos S.D., Koufakis E.I., Polykrati A.D., Bourkas P.D., Causes and Consequences of sparks on the Surface of Insulators of Middle Voltage Lines, in Proc. of INTERFLAM, Nottingham, 2010, pp. 1641-1646.
Περίληψη: The motive of this work was a real incident of fire, which was attributed to sparks and partial discharges of a medium voltage line of the distribution network. This work investigates the causes and consequences of sparks of the medium voltage lines under normal operation conditions as well as under a fire incident. This work presents the occurrence of sparks and partial discharges on insulators and the conditions under which they take place. Furthermore, analytical calculations are given concerning the minimum electrical strength for the initiation of partial discharges on bare conductors of the medium voltage lines as well as for the required insulating ability. From the calculations, the case of the fire caused due to the medium voltage line is examined.
3.2.Halevidis C.D., Koufakis E.I., Anagnostatos S.D., Polykrati A.D., Short-circuit and overheating test of stationary electric contacts, in Proc. of DEMSEE 2010, Sitia, 2010.
Περίληψη: In this work overheating and short-circuit tests are performed on low voltage stationary electric contacts, namely power sockets. From these tests, the real nominal current of the sockets is ascertained. The results show that three out of eight test subjects failed the overheating test and two out of eight failed the short-circuit test.
3.3.Koufakis E.I., Halevidis C.D., Anagnostatos S.D., Polykrati A.D., Breakdown strength measurements of insulating oils under elevated temperature and shake up, in Proc. of DEMSEE 2010, Sitia, 2010.
Περίληψη: In this work, the breakdown strength of insulating oil was measured in room temperature, after shaking up, and after shaking up and heating to 40 oC. The results show that the shakeup decreases the insulating strength and that the heating up reverses the results of the shakeup. In some cases, the heating up increases the insulating strength to values greater than the initial ones (without shaking up). This can be explained using the electro-convection theory and the destruction of the conducting bridges consisting of floating particles.
3.4.Anagnostatos S.D., Halevidis C.D., Polykrati A.D., Koufakis E.I., Bourkas P.D., Partial Discharges on Bakelite Insulators under Impulse Voltage, in Proc. of DEMSEE 2010, Sitia, 2010.
Περίληψη: Partial discharges are a major aging factor of insulators. In this work, measurements are carried out on bakelite insulators under impulse voltage of 1.2/50 μs form, in order to examine the partial discharges occurring on them. The measurements show that partial discharges occur due to impact ionization. Also, the measurements show that apart from the consumption due to partial discharges, a part of the offered energy from the impact ionization is consumed on the insulator due to mechanical stress.
3.5.Halevidis C.D., Koufakis E.I., Anagnostatos S.D., Polykrati A.D., Temperature increase of middle voltage network conductors due to the three operation cycles of reclosers, in Proc. of DEMSEE 2010, Sitia, 2010.
Περίληψη: In this work, the temperature rise of ACSR conductors concerning medium voltage networks is calculated due to the operation cycles of reclosers during a case of fault. The increased resistance of the conductor at the second and third cycle is taken into consideration. This increased resistance has consequently a greater temperature increase compared to the one of the first cycle. From the calculations, it is concluded that the temperature rise is particularly great in the first kilometers of the line, as the total fault resistance is small.
3.6.Halevidis C.D., Polykrati A.D., Karagianopoulos C.G., Bourkas P.D., Protection from the Abruption of the Concentric Cable, in Proc. of EuroPES 2011, Crete, 2011, pp. 280-283.
Περίληψη: In this work, a real event in which a person suffered lethal electrocution from the concentric supply cable is investigated. Specifically, the abruption causes are identified. From the calculation results, it can be concluded that cable abruption is possible due to a direct lightning stroke and its resulting temperature rise from the current and the insulation ignition. Additionally, a protection method against the abruption of the supply cable is proposed, utilizing the PSTN (Public Switched Telephone Network) technology.
3.7Halevidis C.D., Karagianopoulos C.G., Bourkas P.D., Causes of Conductor Abruption during Normal Weather Conditions, in Proc. of EuroPES 2011, Crete, 2011, pp. 284-288.
Περίληψη: In this paper, an investigation of a real event, in which a fire was started due to a low voltage line aluminum conductor being abrupted, is undertaken. The conductor was asymmetrically dented at the abruption point. From the performed calculations, it can be concluded that an abruption cannot be caused by sparking. On the other hand, an abruption can be caused by mechanical stress by shot pellets from a hunting rifle.