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According to a TOM bushing faults, three typical 220kV cable-conductor bushings (COT, TOM and BRDLW) widely used in the power grid are analyzed about diversion structure. Bushing diversion structure, diversion contact surface, current path and installation sensitivity are discussed in the paper. The study found that installation accuracy of TOM bushing has greater effect on contact resistance of diversion path than others. The improper installation of TOM bushing caused overheating defects and finally developed into this bushing fault.

According to two typical COT bushing faults, three typical 220kV cable-conductor bushings (COT, TOM and BRDLW) widely used in the power grid are analyzed about bushing compact structure. Bushing pressing structure, installation clamping force, deformation deviation and sealing system are discussed in the paper. The study found that the installation clamping force and the reeds adjustment range of COT bushing is smaller than others. The manufacturability deviation and the poor condition will cause hidden trouble to the bushing sealing system. Last, several suggestions about bushing maintenance are given for the COT bushing.

Short-circuit withstand capability test of transformers is mechanical strength withstand test under strong current imposed on power transformers, which is a kind of assessment method of comprehensive technical capabilities and technological level of transformer manufacturing. This paper analyzes the theory basis of short-circuit withstand capability test and calculates the imposed short-circuit current value and provides experimental scheme which is verified by the testing. All is to verify the ability to withstand a short circuit of 110kV power transformer.

Firstly, this paper introduces the development of new materials, new technology and new manufacture in power industry of China, energy-saving, low noise and smart distribution transformers are widely used in countryside power grid reconstruction. In this paper, application status and development trend of different types of distribution transformers were introduced and compared in terms of new material and new structure, such as oil-immersed distribution transformer, amorphous core transformer(AMT), dry-type transformer, SF6 insulated distribution transformer, composite transformer and other types of distribution transformers. The development of distribution transformer is mainly based on energy saving, miniaturization, wound core and amorphous alloy nowadays, but the class-H dry-type transformer and tridimensional toroidal-core amorphous alloy transformer are the future direction of development. The technology application of smart distribution grid, power electronics technology and dynamic reactive power compensation technique will also affect the safety and economic operation of distribution transformer.

Firstly, this paper introduces the development of amorphous alloy transformer. According to the technical characteristics of amorphous alloy transformer and the application of Jiangsu power, the comprehensive evaluation about amorphous alloy transformer from the safety performance, the economic performance and the environmental impact are studied comparing with S11 type, S13 type and S15 type transformer. In the safety performance, overload capacity and over-excitation ability of amorphous alloy transformer is insufficient; in the economic performance, low no-load loss, high efficiency, energy saving effect of amorphous alloy transformer is obvious; in terms of environmental impact, the audible noise level of amorphous alloy transformer is higher than that of conventional transformer, and manufacturers need to study to reduce the noise level. Finally, the application recommends of amorphous alloy transformer is presented based on comprehensive evaluation.