Health index has been widely accepted as a powerful tool for monitoring the condition of power transformer insulation system based on various diagnostic parameters. While this approach extensively discussed in literature, not much attention was given to provide effective solutions uncertainty used data. According CIGRE 761, data quality issues may arise due measurement accuracy well incompleten...

A rotating cylindrical electrode apparatus, which provided cylindrical Couette flow, was used to simulate flow electrification in an electric power transformer. The apparatus had Shell Diala A transformer oil filling the annulus between coaxial cylindrical stainless steel electrodes that were either bare metal, or covered by a thin copper sheet and/or EHV-Weidmann HiVal pressboard insulation. E...

It is important to monitor the moisture content of transformer oil in a transformer. One parameter of particular interest is the moisture solubility of transformer oil. It has been reported that transformer oils under different conditions have different solubility. Measurements of solubility for four different types of conditioned oil are presented in this paper: fresh Shell Diala AX oil, lab-a...

Mineral oil is widely being used as insulation for high voltage equipments such as transformer due to its excellent dielectric properties. Recently, due to environment consideration and the long term availability, organic liquid insulations from plantations are being introduced. However, the performance of such insulations in composite with paper should be investigated in order to maintain the ...

The converter transformer is an essential part of the DC transmission system. Compared with traditional oil-impregnated AC transformer, main insulation bears more complex electric field aging stress during long-term operation. influence proportion components in AC/DC composite on still unclear. Therefore, a combined test platform and thermal was built laboratory, accelerated tests oil-paper und...

Power transformers are key components in electrical power supplies and their failure could cause severe consequences on continuity of service and also generates substantial costs. Identifying problems at an early stage, before catastrophic failure occurs, is a great benefit for reliable operation of power transformers. Frequency Response Analysis (FRA) is a new, well-known and powerful diagnost...

In this thesis, power system transients are considered as an opportunity for development of online diagnostics of power components and specifically the insulation systems of power transformers and bushings. Failures of power components and outages can lead to a huge economical loss in the electric power grid. Therefore reliable operation of power grid requires on-line monitoring and diagnostics...