This paper presents the steady and dynamic thermal balances of an overhead power line proposed by CIGRE (Technical Brochure 601, 2014) and IEEE (Std.738, 2012) standards. The estimated temperatures calculated by the standards are compared with the averaged conductor temperature obtained every 8 min during a year. The conductor is a LA 280 Hawk type, used in a 132-kV overhead line. The steady and dynamic state comparison shows that the number of cases with deviations to conductor temperatures higher than 5 • C decreases from around 20% to 15% when the dynamic analysis is used. As some of the most critical variables are magnitude and direction of the wind speed, ambient temperature and solar radiation, their influence on the conductor temperature is studied. Both standards give similar results with slight differences due to the different way to calculate the solar radiation and convection. Considering the wind, both standards provide better results for the estimated conductor temperature as the wind speed increases and the angle with the line is closer to 90 • . In addition, if the theoretical radiation is replaced by that measured with the pyranometer, the number of samples with deviations higher than 5 • C is reduced from around 15% to 5%.

The transformers lifespan depends importantly on its refrigeration. Mineral oils perform this work in the majority of the power transformers. However, this type of coolant has two main drawbacks: low biodegradability and low ignition point. Several alternative liquids are being developed in order to overcome these drawbacks. This paper compares their thermal-fluid behavior with a mineral oil by means of several parameters, such as temperature, flow rate, fluids velocity, convective heat transfer coefficient (h) and the cooling criterion (P). These are calculated using the numerical results of the simulation of a 3D-model of a Low Voltage Winding that belongs to a power transformer with ONAN cooling. The software COMSOL Multiphysics has allowed the simulation of the geometry using a physical model in which buoyancies and viscous forces are the only considered establishing the natural convection. As a result of the comparison, it is clear that the mineral oil is the best coolant liquid. Among the alternative liquids, silicone oil would be the second best coolant fluid, followed by the synthetic and natural esters, respectively. On the other hand, it seems to be clear that the 3D simulations can be used to compare properly the cooling capacities of the liquids.

A hybrid one-pot tandem protocol combining s-block reagents with enzymes (laccase from Trametes versicolor), in aqueous media, at room temperature and under air, is disclosed.

Efficiency in power lines operation is becoming more crucial as the electrification increases and more renewable energies are connected into the grid. New methods and sensors are being added to create smart grids to face these challenges and conductor temperature sensors are one of them. Contact temperature sensors have several problems regarding safety and electronic damage due to the electromagnetic fields induced on the conductors. The goal of this paper is to describe an infrared temperature measurement sensor and to compare contact and non-contact temperature measurements to estimate the temperature of power lines. Measurements were done for almost a year, storing around 150,000 measures of contact and infrared thermometers for many different weather and load conditions. The results conclude that the infrared system can be successfully used to control the temperature of the overhead conductor within a range of less than 4 ∘C difference with respect to contact temperature methods for the 88% of the samples and less than 6 ∘C for the 99%.

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