Numerical 3 Pole Differential Relay : ADR133ASpecificationsOnline display of Phase Current / Differential Current. Latching of fault current value. High Speed operation. Operation is based on fundamental frequency value. Harmonics restrain for Transformer charging and CT saturation condition. Programmable Internal ICT (Interposing CT) ratio to match different transformers having different vector groups. Programmable dual bias setting.ADR133A is a numerical transformer differential relay with dual bias characteristic for two winding transformer.