After special vacuum treatment for the reduction of particle, water and dissolved gas contents, the oil should have the dielectric strength and/or breakdown voltage of > 70 kV. ( IEC 60296, 2020) The breakdown voltage is measured according to Standard IEC 60156 ( IEC 60156, 2018). ( Carey and Hayzen, 2001 Gunderson et al., 2011)Īccording to the international standard IEC 60296 (Editor Edition 5, 2020) “fluids for electro-technical applications – unused mineral insulation oils for electrical equipment”, for transformers and switching the breakdown voltage of the transformer oil gives its resistance to electrical voltage in electrical equipment. The insulating capacity of a hydraulic fluid is crucial when designing the drive assembly of a hydraulic system – a hydraulic compact unit, where the drive electric motor, together with the pump, is often immersed in hydraulic fluid. Insulating properties and electric breakdown voltage Using appropriate on-line sensors, appropriate calibration and calibration of the fluid in question, knowledge of the mechanism of changes and influencing factors, monitoring changes in the dielectric constant, alone or in combination with tracking changes in other quantities, becomes a very advanced approach to online monitoring of hydraulic fluid, which offers many new options ( Tič et al., 2014). On the other hand, knowing and monitoring the changes in the electrical values such as dielectric constant and electric conductivity of a hydraulic fluid provides a more detailed insight into the physical and chemical condition of the fluid, its degree of degradation and the prediction of the remaining service life ( Meindorf, 2005). In this case, the knowledge of the breakdown voltage of the fluid is very important. Thermal and oxidation stability are two of the basic properties hydraulic oils must have, while the electric insulation is an additional requirement which must be met, for example, when the electric motor is submerged in the hydraulic fluid. In some cases the hydraulic fluids are required to have similar properties as the transformer oils, such as insulating properties in other cases the thermal and oxidation stability of the hydraulic fluid are in the forefront. On the basis of known electrical values, we can decide on the design of the hydraulic unit, or on the basis of changing electrical values, we can conclude on the state of the installed fluid ( Tič and Lovrec, 2017 Carey and Hayzen, 2001). These tests somehow include knowledge of the characteristic electrical parameters of a fluid – its characteristic initial values and the course of their change. These are more limited to laboratory tests. Less in use fluid acidity monitoring, FTIR analysis and wear particle analysis are used for more detailed condition analyses. Knowing the viscosity and density of the liquid, determining the presence of moisture, of solid particles and other contaminants, controlling the temperature of the liquid represent the basis. Good knowledge of the physico-chemical properties of hydraulic fluid is a prerequisite for the correct, long-term, economically and environmentally sustainable use of the fluid built into a hydraulic system.
#Hydraulic fluid full
The full terms of this licence may be seen at
Anyone may reproduce, distribute, translate and create derivative works of this article (for both commercial and non-commercial purposes), subject to full attribution to the original publication and authors. This article is published under the Creative Commons Attribution (CC BY 4.0) licence. Copyright © 2021, Darko Lovrec and Vito Tič.
0 kommentar(er)
