Siemens SIPROTEC 5 6MU85 Merging Unit – Process Bus Interface for Conventional and Non-Conventional Instrument Transformers

Main Functions: ، Merging unit for CTs and VTs (conventional & LPITs) ، Bay unit for distributed busbar protection (SIPROTEC 7SS85) ، Breaker control and monitoring ، Backup protection functions ، Phasor Measurement Unit (PMU) capability (IEEE C37.118) ، Sampling and Communication: ، Up to 4 SMV streams (IEC 61850-9-2 LE or IEC 61869 flexible streams) ، 32 analog channels (configurable for CTs/VTs) ، Redundant Ethernet communication via PRP protocol ، Time synchronization: IEEE 1588v2/PTP ، IEC 61850-8-1 (GOOSE, MMS) & IEC 61850-9-2 compliant ، Protection Functions: ، Non-directional and directional overcurrent (50/51, 67/67N) ، Overvoltage/undervoltage (27/59) ، Circuit-breaker failure protection (50BF) ، Auto-reclosing (79), Synchrocheck (25), Trip-circuit supervision (74TC) ، Additional Features: ، Arc protection and breaker wear monitoring ، 4–20 mA analog inputs for process sensors (e.g., pressure, tap changer) ، Temperature monitoring via TR1200 thermo-box ، Web-based access and configuration ، Integrated cyber security (RBAC, event logging, signed firmware) ، Hardware & Design: ، Modular SIPROTEC 5 structure, expandable I/Os (up to 6 modules) ، 1/3 × 19” to 2/1 × 19” housing ، Operating temperature: -40°C to +70°C ، Dual power supply redundancy ، Supported Protocols: ، IEC 61850, IEC 60870-5-103/-104, Modbus TCP, DNP3, PROFINET IO ، Engineering: ، Fully supported by DIGSI 5 software