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In medium voltage distribution network covered conductors are used to improve reliability and reduce interruptions and faults caused by snow, ice, storm and fallen trees; however covered conductors are more vulnerable than bare conductors against lightning caused burndown, therefore arc protection devices should be used. To study covered conductor overhead lines in case of direct lightning strike...
In a stage of development of the project and during the exploitation of transmission line (TL), the specialists have to solve one of the most complicated problems — insulation failures llashover rate (IFFR). The main indicator of the IFFR of TL is the minimization of the probability of outages, which is irreversible destructions of the isolating TL designs. When using valid normative documents, for...
Large power transformers are an important component of the power system, because mainly they are the connecting points between generators, transmission system and distribution system. Although transformers are considered as electrical devices with high operation reliability, various faults can occur due to internal or external causes. Mechanical defects mainly are caused by electrodynamic forces and...
Technical condition of large power transformers has large impact on reliability of a power system since they are the connection points for generators and distribution system. Power transformers can experience various faults that can disrupt their reliable operation such as mechanical defects caused by magnetostriction or electrodynamic forces. Magnetostriction is a phenomenon occurring in transformer...
Any failure of a power transformer can result in serious consequences for a power system. Bushing failures, mechanically damaged windings or deterioration of solid insulation may cause unexpected power line cut-offs and financial losses to a company. Faulty operation of the on-load tap changer (OLTC) caused by increased contact resistance, contact misalignment or broken drive mechanism also reduces...
Risk assessment for power transformers has long been an effective tool to analyze transformer conditions in order to prevent damage on transformers, extend transformer's life time and reduce maintenance costs. Various parameters can be evaluated, and decision can be made manually or with the help of mathematical model. A new mathematical risk-assessment model for power transformers is being developed...
Lightning protection system is an effective way to properly protect structures against hazardous effects of lightning strike. Lightning protection zone is an essential parameter of lightning protection system, because it determines whether structure is protected against lightning strikes. The rolling sphere method is commonly used to estimate lightning protection zone, but it neglects some significant...
Reliability of a power system depends on its equipment. As power transformers are essential elements in substations, reliability of power transmission system largely depends on their operating and technical conditions. Therefore complicated maintenance strategies are applied including various diagnostic methods and a thorough evaluation of the acquired results. Although diagnostic tests aid the evaluation...
The paper provides a short insight into the structure of Latvian high voltage transmission network, describing existing system of complex diagnostic and analyzing maintenance data to reveal the most frequent locations of faults in power transformers. Modified inspection schedule of power transformers is described that serves as a base for developing effective algorithm for assessment of technical...
The paper presents the description of the meta-model synthesis method based on numerical calculations of magnetic field of an electric machine. The method of finite elements is applied for numerical calculations of magnetic field, and metamodelling method Adaptive Basis Function Construction is used for generating corresponding polynomial. Proposed metamodel allows analyzing how geometric dimensions...
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