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Generally planar transformers experience significant capacitive coupling between the primary and secondary windings. A novel shielding configuration which overcomes the problems of conventional electrostatic shields is presented While the technique is focused on planar transformers, it is shown that similar benefits may be obtained with conventional transformers. The operation of the new shield relies...
The shaft voltage of a synchronous generator has been simulated in a transient 2D finite element methods (FEM) package. It is not only shown that it is possible to accurately simulate the shaft voltage but that the key way and weld recesses in the stator laminations are major causes of the shaft voltage in this machine. The effects of the key way and weld recesses on the shaft voltage are individually...
Hot spot temperature (HST) is the most important parameter in the operation of power transformers. The HST has to be held under a prescribed limit. HST has a considerable effect on the insulation aging. Therefore detecting, monitoring and removing the HST could be a very important and necessary action for Utilities. A new design of oil spraying and its effect, along with a thermal management in a...
Developed countries have become accustomed to having access to an electric grid and it is taken for granted that electrical power is available at any time. However, this is not the case in many remote villages in developing countries where insufficient infrastructure has left many people short of a basic energy supply. To address this need, a portable hand crank generating system is proposed in this...
For many utilities the asset base is ageing at a time when the business focus is on system availability and energy not supplied. For the major plant items, such as generators, cables and transformers, where failure leads to long term unavailability, it is important to be able to define the risks of future operation. The processes used to achieve this have many common threads across the technologies,...
AC-losses in gapped-core planar inductor windings seem to be dominated by eddy losses induced by the time varying fringing flux near the air gap. Shaping the windings in the region of the gap reduces AC-losses but the reduction in width of planar foil conductors causes the DC-resistance to increase. The winding shape can be optimized using FEM-tools but the process is very time consuming. If the DC-resistance...
AC-loss analysis in gapped-core inductor windings can be performed using finite element analysis (FEM) software with good results. The process however becomes very time consuming especially if the winding is shaped in the vicinity of the air gap. The lack of closed form solutions for optimization of shaped windings emphasizes the need for alternative techniques offering solutions quicker than running...
Sweep frequency response analysis (SFRA) is one of the most powerful diagnostic tools for assessing mechanical damage to a transformer winding. Analysis of the results, which are in the form of frequency response traces can, however, be daunting to new users. One approach is to attempt automated analysis, and this paper presents an approach using cross- correlation coefficients. This is a power signal...
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