1.Through current transformer: A current transformer used to pass through a panel or wall. 

2Pillar type current transformer: the current transformer installed on the plane or pillar, doubles as a primary circuit conductor pillar. 

3. BUSHING type current transformer: a current transformer that is directly mounted on an insulated bushing without primary conductors or primary insulation. 

4: BUS-TYPE CURRENT TRANSFORMER: no primary conductor but a primary insulation, directly installed in the bus on the use of a current transformer.