GSW 10 | 20 | 30 Indoor Support-Type Current Transformer, Block Type, Big Type acc. DIN 42600, Part 5. The Insulation by brown epoxy resin having excellent mechanical and electrical properties. Core and windings are cast in one single operation. The CT has a base plate or base rails. The base plate of the CT consists of aluminium alloy and the base rail consists of hot dip galvanised steel. The active part consists of one or multiple toroidal core(s) with homogeneously applied secondary and primary winding. The secondary terminal box is sealable. Each secondary terminal has the possibility of a direct screw connection. On delivery, the first terminal of a core is visible connected to ground /(earth). A ground terminal is located on the side of the CT opposite the terminal box.