Rectangular shape with stepped window to fit bus bar as well as single or multi-cables.Main applications are metering and instrumentation,Filled with epoxy resin inside casing. Full,complete ratio range with six sizes for more application choices.With its enhanced burden feature,30×30I′s rated burden is able to reach 5 to 10VA with the primary current lower than 100A,when the turns of the cable going through the core are 2 to 3.