Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
Search results
88 records were found.
Partial discharge (PD) measurements are an important tool for assessing the health of power equipment. Different sources of PD have different effects on the insulation performance of power apparatus. Therefore, discrimination between PD sources is of great interest to both system utilities and equipment manufacturers. This paper investigates the use of a wide bandwidth PD on-line measurement system consisting of a radio frequency current transducer (RFCT) sensor, a digital storage oscilloscope and a high performance personal computer to facilitate automatic PD source identification. Three artificial PD models were used to simulate typical PD sources which may exist within power system apparatus. Wavelet analysis was applied to pre-process measurement data obtained from the wide bandwidth PD sensor. This data was then processed using co...
There are a number of medium voltage (MV) power distribution cable networks worldwide that are constructed predominantly of mass impregnated paper cables - London being one of these. Paper insulated lead covered (PILC) cables were extensively laid in the 50s and 60s before the introduction of cheaper polymeric alternatives that were sufficiently reliable. The current operational state of these networks has shown a gradual increase in failure rates of the previously reliable paper cables that are drawing to the end of their expected design life. Utilities are faced with the prospect of the impending failure of large sections of their prized asset and are keen to develop tools to better understand the health of their hardware. The analysis of partial discharge (PD) signals produced by the cables has been identified as a economically viab...
This paper is concerned with an experimental study into the degradation processes that occur when voids in solid dielectric materials experience high applied electric fields. A method has been developed for manufacturing 2mm thick samples of silicone resin that contain a single void of around 1mm diameter. Five samples are simultaneously electrically stressed under an applied ac sinusoidal voltage of 12kV for 6 hours that is then increased to 15kV until a sample fails. During the stressing period, PD data is regularly acquired. The remaining 4 samples are then inspected for signs of degradation. Degraded samples that have not suffered catastrophic failure and contain pits or evidence of electrical trees were cut open using an RMC MT-7 ultra-microtome equipped with a CR-21 cryo-system set at -110。C in order to provide a surface containi...
