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VORŠIČ, Ž., PIHLER, J., MARUŠA, R.
HEATING OF CONDUCTORS IN STEADY STATE II
KOMUNALNA ENERGETIKA / POWER ENGINERING, 26
Factors such as voltage drop, power losses, stability, protection etc are important when selecting conductors cross-section in distribution and transmission networks. Important factor is also the rise of the temperature over the surrounding temperature: it is necessary to know the maximum continuous conductor current since it determines the maximum permissible temperature of conductor. The temperature of the conductor affects the conductor sag between the columns and determines the change in tensile strength due to warming. For short connection lines conductor temperature in emergency conditions is relevant for selection of the conductors cross-section.
VORŠIČ, Ž., KUMPERŠČAK, V., PIHLER, J.
HEATING OF CONDUCTORS IN STEADY STATE
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
Several factors influence the choice of conductor cross-section when planning distribution and transmission networks, such as voltage drop, loss of power, stability, protection and others. Important factor is also conductor temperature rise above surrounding temperature. To determine it one must know maximum continuous current which determines maximum allowed conductor temperature. The temperature of the conductor affects the conductor sag between the pillars and determines the change in tensile strength due to heating. Conductor temperature is authoritative guide for selecting conductors for short connecting lines in extreme condition.
Three temperatures are relevant: Joule heating depends on average conductor temperature and convection and radiation depends on conductors’ surface temperature. Change (decrease) of tensile strength is in first approximation dependent on temperature of strands in the middle of conductor.
Article shows how individual influencing factors act on conductor by heating or cooling it in steady operation.
VORŠIČ, Ž., PIHLER, J., KITAK, P.
ENVIRONMENTAL IMPACT OF SEMIINSULATED CONDUCTORS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 18
For overhead power lines, there are increasingly used compact conductors with carbon core. If such a conductor is »incomplete« isolated, we get covered conductorm which is mechanically stronger and what is even more important, it is spatially less wasteful. Furthermore, because of the isolation the electric field strength is lower near such a conductor.
There is a design of a covered conductor given in this article, which we could install on the existing 220 kV columns and so increase the transmission capacity of the Slovenian electricity network. The integration of regular energy infrastructure is increasingly demanding, therefore we investigated the impact of such covered conductor for the highest voltage levels to the environment. We compared the analytical calculation of the electric field strength near the proposed covered conductor with the method of finite elements. The results were evaluated according to the regulation on electrictromagnetic radiation in the natural and living environment.
RIBIČ, J., PIHLER, J., VORŠIČ, J., VORŠIČ, Ž.
MODELING TRANSFORMER IN ELECTRIC NETWORK CALCULATIONS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 15
Computer aided load flow calculations and short-cicuit analyses are well known and technically soficticated software for with solutions for planing and operating are available on market. Deficiency of such software is usually lack of possibility to significantly modify elements. Three windigs transformers are mainly presented as two windings tranmsformers and sometimes lack of data is the obsticle for calculations. Article presents results of the research on how including third windings influence load flow and short-circuit calculations.
VORŠIČ, Ž., PIHLER, J., VORŠIČ, J.
ELECTRIC FIELD OF OVERHEAD LINE PUAC 2150/495/65 FOR 400KV
KOMUNALNA ENERGETIKA / POWER ENGINERING, 11
Covered conductors are not so vulnerable, because of the outer coat. This fact allows it to reduce the space between the phase conductors of covered conductor to only third of the space, which is the case by uninsulated conductors.
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