In view of such issues as long maintenance cycle and high cost after the fault of bushing for transformer

a type of oil circuit isolation plug-in design for the bushing is proposed

which separates partially the oil of the bushing from the oil tank of transformer through the base structure

so that the inner cavities of the base and of the oil tank of transformer form two independent cavities

thus making the transformer bushing pluggable and greatly simplifying the maintenance process. The insulation level of the capacitor core is an important performance indicator of the bushing. For this reason

how to perform the improved design of the rubber-impregnated paper capacitor core of the pluggable bushing is specifically discussed in this paper and the prototype has been manufactured. For verifying the design correctness of the base structure and capacitor core

simulation and test verification are developed in this paper

in which

the simulation verification is to set up a integrated three-dimensional electric-magnetic-thermal coupling mod-el of the bushing to analyze the temperature rise and electric field distribution under the power frequency conditions

focusing on the effects of Joule heat

eddy current loss and dielectric loss on the temperature rise. The simulation results show that the maximum field strength of the capacitor core of which the design is improved in coordination of the rising base is about 2.29 kV/mm and the capacitor core has sufficient safety margin and good ability to improve the electric field distribution. The highest temperature of the bushing under the power frequency condition appears near the plugging head of the base

which is 97.215 ℃ and meets design requirement of the bushing. The power frequency withstanding voltage test and temperature rise test are performed respectively

the result of the former shows that the designed prototype has sufficient insulation and of the latter show that its difference from the simulation is very small. Both simulation and test show that the design has better insulation and current-carrying ability.