Technical Specifications Basic Identification Brand: ALSTOM / Areva T&D Model: UMT162 Product Type: Numerical Transformer & Feeder Protection IED Application: MV/LV distribution transformer, railway traction auxiliary transformer, medium voltage feeder bay protection Auxiliary Power Supply Rated Control Supply: DC 110V / DC 220V wide dual range input Operating Voltage Range: 77~137.5 VDC (110V system); 154~275 VDC (220V system) Standby Power Consumption: ≤16W Anti-surge Performance: Withstand 2kV transient surge per IEC 61000-4-5 CT & VT Analog Input Parameters CT Secondary Rated Current: Switchable 1A / 5A, 50Hz nominal frequency VT Rated Voltage Input: 100V AC residual / phase voltage Input Burden: CT channel burden ＜0.8VA per phase Measurement Precision: Class 0.5S for current sampling, Class 0.2 for voltage & power measurement Integrated Core Protection Functions Transformer Main & Backup Protection Phase two-stage overcurrent (IDMT inverse curve + instantaneous short-circuit trip) Sensitive residual earth fault two-stage protection Thermal overload thermal image monitoring for transformer winding temperature simulation Negative sequence unbalance protection against three-phase load asymmetry Broken CT supervision, trip circuit continuous supervision Voltage & Abnormal Grid Supervision Overvoltage / Undervoltage lockout protection Voltage unbalance monitoring, neutral displacement protection Overfrequency / underfrequency load shedding logic Special Transformer Logic Inrush current restraint logic to avoid mal-operation during transformer energization Configurable transformer auto-reclose interlock logic