Transformer Disconnect Terminal Strips per TAB These current transformer terminal blocks were developed in collaboration with various grid operators to create ready-made, fast and efficient solutions for the measuring point operator. Thus, the 821-2 Series sets** offer various advantages in terms of standardization, conformity to standards (VDE-AR-N 4100 and DIN EN 61869-2), safety and separability. According to the technical connection requirements (German = Technische Anschlussbedingungen), these sets are indispensable for uninterrupted processing of measurement, testing and maintenance work on transformer systems. These sets are delivered ready for installation and without a DIN-rail for the end user. They are developed for the German energy market.