The W12CDA current transformer is an indoor epoxy resin cast product designed in a maximum circuit voltage 12㎸-class insulation performance,and the less voltage(3.6㎸,7.2㎸) product has the same dimensions. This product has a miniature light-weight compact structure of support type designed according to the international standard DIN42600(Part 8) to be very suitable for standard switchboards installed in a narrow space. In addition,this can be designed and fabricated in a single or multiple ratio type such as 1 core and 2 cores.