Siemens 7SS52 Numerical Protection Relay – Advanced Medium Voltage (MV) Protection Device for Feeders, Transformers & Motors | IEC 61850 Compliant

Siemens 7SS52 Numerical Protection Relay 

Overview

Key Features

• Protection Functions:
  • Overcurrent (50/51), Earth Fault (50N/51N), Directional OC, Thermal Overload
  • Optional: Distance Protection (21), Breaker Failure (50BF), Arc Flash Detection
• Communication & Automation:
  • IEC 61850 (GOOSE, MMS), Modbus RTU/TCP, Profibus DP
  • Integrated web server for remote access
• High Accuracy: Class 0.5 for metering; <20 ms trip time
• User-Friendly Interface: Graphic LCD with LED indicators, front USB port
• Cyber-Secure: Role-based access, audit logs, firmware authentication

Technical Specifications

• Voltage Rating: Up to 36 kV (phase-to-phase)
• Current Input: 1A or 5A (CT secondary)
• Auxiliary Supply: 24–250 V DC / 110–230 V AC
• Standards Compliance: IEC 60255, IEC 61850-3, IEEE C37.90
• Operating Temperature: –25°C to +55°C
• Mounting: Flush or panel mount (DIN rail optional)

Ideal Applications

• Industrial MV switchgear (steel, cement, pharma)
• Renewable energy substations (solar/wind farms)
• Urban distribution networks (DISCOMs)
• Railway traction power systems
• Critical infrastructure (airports, data centers)