1,720,986 research outputs found
Investigating the Physiochemical Effects of Verdigris Contamination found on a Polymeric Cable Sealing End
No full textA cable sealing end is a crucial power system component as it is responsible for the vital task of successfully terminating cables. Recent reports on the diagnosis of ex-service units have led us to investigate possible contaminations that could impact the dielectric properties of a cable sealing end. Verdigris, often blue/green in color, is one such contaminant that is observed on the surface of a cable stalk. This investigation aims to understand the possible cause of this contamination and its impact on the dielectric liquid used inside a polymeric cable sealing end. To achieve this, the current study is devised in two parts. First, a sample of the verdigris is scraped off from the cable stalk surface and analyzed. The elemental composition of the blue verdigris is analyzed using energy-dispersive X-ray methods on a scanning electron microscope. Second, sonication ageing tests are performed on samples of silicone oil that have been contaminated with verdigris. Elemental analysis shows traces of carbon, oxygen, sodium, silicon, tin and copper contaminations as the primary components of the verdigris present in different percentage. The results from the second half of the study obtained shows an increment in dielectric permittivity and moisture measurements, whereas not much change was reflected in the UV-vis analysis when compared with fresh oil sample
Electrical ageing of silicone oil
No full textIn view of its widespread use in cable terminations, new results pertaining to electrical aging (i.e. exposure to repeated electrical discharge events) of silicone oil are reported. A new piece of equipment allowed the discharge characteristics to be controlled and the resulting blackening was correlated to the change in dielectric properties. End of life conditions were determined and the feasibility of a simple optical probe was explored. This could give the operator warning of when the oil is excessively aged, allowing remedial action to be taken
Investigating the physiochemical effects of aging silicone oil using sonication as a means of mimicking electrical aging
No full textSilicone oils are used in cable sealing ends owing to their combination of excellent dielectric properties, high oxidation resistance, and thermal stability. This paper aims to investigate how electrical stresses induced by sharp edges and protrusions inside the insulating device could lead to alterations in the chemical and dielectric properties of the silicone oil. Herein, electrical stress in the silicone oil samples is induced using a sonication technique. The physicochemical changes in the aged oil samples are analyzed using UV-vis spectroscopy, Fourier-Transform Infrared spectroscopy and dielectric response spectroscopy. The results provide experimental evidence that the proposed method can be adopted as an alternative method for reproducing the effects of electrical stress on oil samples
A review on the relevance of standards for silicone insulating liquids used in Cable Sealing Ends
No full textInternationally recognised standards by organisations such as ASTM and IEC are widely known and relied upon in all areas of engineering. One example in high voltage electrical engineering is the employment of standards giving material specifications to make decisions on the suitability of materials for a specific purpose. However, by their nature as reference documents, some of these standards lack reasoning and explanations about the derivation of the values stated. Others were written many years ago with only cursory updates being made at reviews since. [... ...] Standards relevant to silicone liquids used in CSE from the standpoint of theoretical and empirical research are discussed. This article aimed to identify and suggest reforms based on often unnoticed observations
Data for Characterization of Silicone Oil used in HV Cable Sealing Ends
Get PDFDataset supports:
Virtanen, STH, et al. (2019). Characterization of Silicone Oil used in HV Cable Sealing Ends. Paper presented at 26th Nordic Insulation Symposium, Tampere, Finland, 12/06/19 - 14/06/19.</span
Investigation of incipient faults in 66 kV oil-filled cable sealing ends
Get PDFThis paper reports on the investigation of incipient fault mechanisms of a widely used family of Cable Sealing Ends (CSEs) which use an earthed metallic clip on top of the stress cone to fasten the cable termination stress grading. Finite element simulations indicate that the clip is causing localised electric field enhancement which could also cause impurities in the oil to move towards the clip under the influence of the dielectrophoretic force. Accelerated ageing tests of stress cones in the laboratory have corroborated the simulation results, with the high electric field causing degradation of the semi-conducting tape underneath the clip as well as initiation of tracking on the surface of the stress cone originating from the edges of the clip. Partial discharge (PD) testing using a bespoke test rig in the high voltage laboratory has shown that incipient faults originating from the ageing of the solid CSE materials can only be detected after surface tracking has progressed substantially. Even then, the intermittent nature of PD activity can pose a risk to the accurate condition assessment of CSEs if continuous monitoring is not employed and if the ultra-high frequency method is used on its own
A comparative analysis of different dielectric fluids for cable sealing ends
No full textA growing interest is observed in research to explore biodegradable alternative fluids as liquid insulation in high voltage equipment, due to their dielectric strength, environmental friendliness and enhanced fire safety. The present report deals with comparing the performance of possible alternative oils with silicone oil, which is typically used in the cable sealing ends. A detailed study of various physicochemical aspects and the impact of moisture ingress on these properties of mineral oil, natural and synthetic ester oil, and silicone oil is conducted. This work aims to identify the best liquid dielectric suitable for its application for cable terminations
Characterization of silicone oil used in HV cable sealing ends
No full textExisting polymeric cable sealing end (CSE) typically contain silicone oil as an insulating liquid between the cable core and the outside of the CSE. In recent years, a number of performance issues have been identified with silicone oil filled CSEs. To understand the reasons for the observed behavior of silicone oil, a range of characterization methods are reviewed, to allow investigation of the influence of moisture, potential chemical contaminants and the compatibility with CSE materials. The water content of all the oils studied was above the limit given in IEC 60836 (2015) for new silicone oil. There is no significant difference between the moisture content, whether the oil is used in CSE or new. Neither did the Fourier infrared (FTIR) spectroscopic analysis show difference between the oils. Preliminary results from gas chromatography connected to mass spectrometer (GC/MS) clearly show structural differences between unused expired oil and new oil samples particularly that species suspected to be cyclic siloxane appear to be present in the expired sample
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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