Numerical 3 Pole Differential Transformer Protection ADR233A Relay Specifications Online 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. SCADA compatibility. IEC60870-5-103 protocol. Latching of Last 5 fault along with date and time stamp. 25 Cycle of disturbance record and 100 Event memory. ADR233A is a numerical differential transformer protection relay with dual bias characteristic for two winding transformer.