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 ${}^{\circ }$C difference with respect to contact temperature methods for the 88% of the samples and less than 6 ${}^{\circ }$C for the 99%.

Temperature is one of the most relevant physical quantities that affects almost all processes in nature. However, the realization of accurate temperature standards using current temperature references, like the triple point of water, is difficult due to the requirements on material purity and stability of the environment. In addition, in harsh environments, current temperature sensors with electrical readout, like platinum resistors, are difficult to implement, urging the development of optical temperature sensors. In 2018, the European consortium Photoquant, consisting of metrological institutes and academic partners, started investigating new temperature standards for self-calibrated, embedded optomechanical sensor applications, as well as optimised high resolution and high reliability photonic sensors, to measure temperature at the nano and meso-scales and as a possible replacement for the standard platinum resistant thermometers. This article presents an overview of the results obtained with sensor prototypes that exploit photonic and optomechanical techniques for sensing temperatures over a large temperature range (5 K to 300 K). Different concepts are demonstrated, including ring resonators, ladder-like resonators and suspended membrane optomechanical thermometers, highlighting initial performance and challenges, like self-heating that need to be overcome to realize photonic and optomechanical thermometry applications.

We report new developments in instrumentation and techniques for both acoustic (speed of sound) and radiometric primary thermometry methods. These include both new cylindrical resonators for extending acoustic gas thermometry to higher temperatures and absolute radiation thermometers incorporating InGaAs detectors to extend primary radiometry to lower temperatures than can be achieved using Si-detector based instruments. These new approaches have been established in order to determine the difference between thermodynamic temperature, T , and the International Temperature Scale of 1990 (the ITS-90), T ₉₀ , over the temperature range from 430 K to 1358 K as part of the three-year EMPIR project ‘Implementing the new kelvin 2' (InK2). This paper describes the facilities and measurement methodologies for measuring T — T ₉₀ at each of the different institutes, along with an assessment of the target uncertainties. The work is ongoing, but we anticipate that the results of these measurements will ultimately be pooled to provide consensus values of T — T ₉₀ with associated estimated uncertainties. These consensus values will initially feed into the technical annex of the mise en pratique for the definition of the kelvin (MeP-K-19) and, if required, will be used to help to provide a foundation for any future temperature scale.

The current state of the art for temperature realization and dissemination above 1300 K is through the MeP-K-19 [1]. A limited set of high-temperature fixed points (HTFPs), an essential component of the MeP-K-19, has their temperature determined (Co–C (1597 K), Pt–C (1011 K) and Re–C (2747 K)). It is really a need to increase the HTFPs available for realization and dissemination of the high-temperature MeP-K. Fe–C (1426 K) and Pd–C (1765 K) has been less investigated, their thermodynamic temperature hasn’t been definitively determined, and they have been considered good candidates for their inclusion in the MeP-K in the EMPIR project “Real-K” [2]. This paper describes the construction, characterization, and measurement of HTFPs of Fe–C and Pd–C at Centro Español de Metrología as part of its contribution to the EMPIR project “Real-K”. Cells made have hybrid-type crucibles and they have been filled applying the piston method. A series of 6 HTFPs has been constructed: 3 Fe–C and 3 Pd–C. Points of inflection of the melting plateaux are repeatable after several initial measurement cycles. Their corresponding International Temperature Scale (ITS-90) temperatures (t₉₀), referenced to a Cu fixed point, and thermodynamic temperatures (t), by means of the spectral responsivity calibration, have been calculated. Additionally, the influence of the furnace in the temperature assigned to the cells has been determined for different furnaces types (one zone and three zone) and different temperature profiles.