Research of the Changes in the Structural Group Composition of Transformer Oil During Operation

The actual issue of the electric power industry is the diagnostics of equipment to timely detection of emerging defects and their prevention. The aim of presented work is the development of a method for monitoring the state of transformer equipment based on the determination of structural-group composition of transformer oil. The goal is achieved by measuring spectra of oil in the near-IR (infrared) region. The method of investigation isapproximation of obtained spectra of transformer oils on the basis of reference compoundsspectra.A new method for determining the structural group composition of oils was proposed. It is distinguished by a significant simplicity and directly related to the characteristics of the molecules in comparison with the existing methods for determining the structural group composition from nomograms.Optical spectra in the near-IR range of fresh and used samples of GK transformer oil in the range of 10250-11750 cm-1were recorded and analyzed. It was shown that during the aging transformer oil fraction of CH2-groups decreases, CH3-groups fraction increases somewhat, CH-groups fraction is significantly increased, thereby confirming the effect of increasing the proportion of aromatics in such systems reducing the amount of cycloalkanes, paraffins are most stable. This fact can be used to develop monitoring systems for power oil-filled transformers. Determination of the structural group composition of the oil and its changes during operation will allow monitoring the oil condition, the technical condition of the transformer and to determine the origin of thermal and discharge defects

Electronic and magnetic properties of [Fe(3-MeO-Qsal)2]Y•n solvent (n = 0,1) complexes

[Fe(3-MeO-Qsal)2]Y (Y = PF6, BF4, NCS, NO3, BPh4) compounds were synthesized using the diffusion method and studied by the electron spin resonance and the magnetic susceptibility methods in the temperature range (5-300) K. Coexistence of spatially separated high-spin and low-spin fractions in these compounds was observed. Low-spin fraction of all compounds reveals the antiferromagnetic correlations at low temperatures. High-spin fraction of complexes with Y = PF6 demonstrate the weak ferromagnetic properties due to exchange interaction between complexes in whole temperature range. Influence of outer-sphere anion on the spin state, the electronic properties of low-spin Fe(III) complexes is demonstrated

Spin crossover properties of Fe(III) complexes in [Fe (bzacen)(tvp)]BPh<inf>4</inf>·nSolv chain structures: EPR study

© 2020 John Wiley & Sons, Ltd. Two types of Fe(III) polynuclear iron(III) 1D-chain coordination compounds of the general formula [Fe (L)(tvp)]BPh4 nSolv, where L = dianion of N,N′-ethylenebis (benzoylacetylacetone)2,2′-imine (bzacen), tvp = 1,2-di(4-pyridyl)ethylene were synthesized and studied by the electron paramagnetic resonance (EPR) and magnetic susceptibility methods in the temperature range (100–300) К. Two types of spin-variable complexes are formed depending on the time of precipitation of the complexes from the same solution leading to differently solvated species. They have different characteristics of the local ligand field and the spin transition behavior. The thermodynamic parameters of spin transitions were determined from the temperature dependence of the EPR signals integral intensity. The energy levels splitting values obtained by analyzing g-factors of low-spin Fe(III) centers evidenced not only on the crucial role of low-symmetry distortions on the principal possibility of spin-crossover processes, but also on the temperature peculiarities of spin transitions