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IEEE C57.19.100-2012 pdf free

IEEE C57.19.100-2012 pdf free.IEEE Guide for Application of Power Apparatus Bushings.
The thermal loading capability of bushings varies with the way they are loaded, the way they are designed, and the ambient conditiorts in which they are applied.
4.1.1 Basis of rating and rationalization of thermal requIrements rating
Capacitance-graded. paper-insulated bushings that, at rated current, meet the requirements of IEEE Sid C57.19,00-1991 and earlier versions of that standard may be applied in either 55 °C or 65 °C rise transformers. IEEE Std C57.19.0O-1991 stales thai the temperature of the oil in which the lower end of the bushing is immersed shall not exceed 95 °C when averaged over a 24 h period. Refer to IEEE Std C57.9 11M for loading requirements and operating oil temperatures of power transformers. Operation above normal temperature
When operating a bushing at rated current in conjunction with a 65 C average winding rise rated transformer, the hottest-spot temperature of the bushing is limited to a 65 °C rise over ambient or a 105 °C total temperature because of the use of temperature index 105 insulating paper for the bushing condenser. If it should be determined that a transformer develops a top oil rise of 65 C at rated current when operating in a 40 °C ambient, then the hottest-spot temperature of the bushing can be expected to exceed 105 °C. In addition. transformers can be expected to have bushing temperatures above 105 °C when loaded in accordance with IEEE Std C57.91.
In each instance, the normal life expectancy of the bushing will be shortened by the higher operating temperatures. The loss-of-life of a bushing will, like transformers, be a function of the actual temperature and the time operating at that tcrnperature
The severity of loss-of-life in a bushing can be minimized by installing bushings that have nameplate ratings greater than the transformer current ratings or by using bushings with special high-temperature insulation. An alternative is to operate the bushing with the higher inherent temperatures and accept a moderate degree of accelerated aging. as it is presently recognized for transformers.
41.1.2 Factors influencing bushing aging
There are several factors that tend to decrease the severity of bushing aging. These are as follows:
a) The top oil rise of many transformers is significantly below 65 °C when the transformer is operated at nameplate loading. This is most likely to occur on forced oil-cooled (OFAF or ODAF) transformers.
b) Bushings are totally sealed from the atmosphere at the time of manufacture, thus preserving their dielectric and thermal integrity.IEEE C57.19.100 pdf download.

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