In this paper, we performed an insulation diagnosis technique for oil-immersed power transformers by an acoustic detection method. Electrode system such as needle to plane electrode was fabricated to simulate a defect of power transformers. In addition, the frequency spectrum of acoustic signals with partial discharge (PD) in insulating oil was analyzed. From the FFT result, the frequency spect...

The life expectancy and load capacity of oil-immersed power transformers are intimately associated with the winding hot spot temperature (HST). Thus, accurately predicting HSTs is essential in evaluating the life expectancy of power transformers and in preventing thermal failure. Previously, support vector machine (SVM) has been successfully employed to solve the regression problem of nonlinear...

The overall life of oil-immersed power transformers depends on the long-term life of the oil–paper insulation system throughout continuous operation. Studying the reliability assessment methods for oil–paper insulation can help determine the reliability level of power transformers accurately, and ensure their safe and stable operation. In the present paper, the life of oil–paper insulation is p...

To improve the fault diagnosis accuracy for power transformers, this paper presents a kernel based extreme learning machine (KELM) with particle swarm optimization (PSO). The parameters of KELM are optimized by using PSO, and then the optimized KELM is implemented for fault classification of power transformers. To verify its effectiveness, the proposed method was tested on nine benchmark classi...

the infrastructure of the electricity grid and super grid system in the hitherto industrialized world was to a large extent built up in the decades following world war ii with a peak in investments around 1960-1980. this means that the flotilla of power transformers is now starting to reach projected lifetime of around 40 years. during the last couple of decades there has also been an ongoing d...

At high frequency, the winding losses of power transformer due to skin and proximity effects becomes a significant component in the loss calculation of the transformer efficiency. This paper examines the winding losses associated with these effects for planar-type low-profile transformers that are suitable for high frequency high density soft switching power supply application. The transformer ...

Power transformers are one of the most important components in the electrical energy network. Extending transformer life is very economically valuable due to power outage. Therefore the development of instruments to monitor the transformer condition is of great interest. Detection of partial discharges (PDs) in power transformers is an effective diagnostic because it may reveal and quantify an ...

The energizing of large power transformers has long been considered a critical event in the operation of an electric power system. When a transformer is energized by the utility, a typical inrush current could be as high as ten times its rated current. This could cause many problems from mechanical stress on transformer windings to harmonics injection, and system protection malfunction. There h...

Fault diagnosis of power transformers have always drawn the attention among the users, without removing the transformers from the service. Thus it is necessary to detect the incipient fault of a power transformer at an early stage and diagnose properly on optimum way. Dissolved gas analyses (DGA) is widely used to detect incipient faults in oil filled power transformers. Throughout the world, d...

Present development and production of power transformers with lower losses in addition to replacement of outdated transformers assume regular measurement of losses in both load and no-load regime. These measurements are very demanding especially in the case of on-situ measurements. The complexity of the measurements grows with the size of transformer. This paper presents one typical test of los...