Siemens SIPROTEC 5 7SJ85 Feeder & Overcurrent Protection Relay

The Siemens SIPROTEC 5 7SJ85 is a versatile and high-performance modular feeder protection relay designed for protecting feeders and distribution networks in medium- and high-voltage power systems. Built on the advanced SIPROTEC 5 platform, it provides fast, selective, and reliable protection to ensure system stability and minimize outages.

The relay combines feeder protection and overcurrent protection functions within a single device, making it suitable for a wide range of applications including radial, ring, and meshed networks. It supports both primary and backup protection schemes, ensuring comprehensive protection coverage.

With its modular and expandable I/O architecture, the 7SJ85 allows flexible configuration based on project requirements. It integrates protection, control, automation, monitoring, and power quality functions, making it ideal for modern digital substations.

Engineered with DIGSI 5 and supporting IEC 61850 communication, the relay ensures seamless integration, advanced automation, and high cybersecurity standards for future-ready power systems.

Main Function

• Feeder Protection
• Overcurrent Protection

Tripping

• 3-pole tripping
• Fast and selective fault isolation

Technical Specifications

Protection & Functional Features

• Feeder protection for:
  • Radial networks
  • Ring networks
  • Meshed distribution systems
• Overcurrent protection (time-dependent & instantaneous)
• Detects:
  • Phase faults
  • Earth faults
• Supports:
  • Directional and non-directional protection
  • Backup protection for lines and equipment
• Adaptive protection ensures:
  • High reliability under fault conditions
  • Selective fault isolation

Hardware & Modular Design

• Fully modular and expandable I/O configuration
• Available in multiple standard variants
• Typical configurations:
  • CT/VT inputs configurable as per application
  • Binary inputs: flexible range (~5 to 31)
  • Binary outputs: flexible range (~8 to 46)
• Scalable design for future expansion
• Conformal coating for harsh environments

Communication & Protocols

• IEC 61850 Edition 1 / 2 / 2.1 compliant
• GOOSE messaging for high-speed communication
• Supports:
  • PRP / HSR redundancy
  • Modbus TCP, DNP3
• Enables seamless integration into digital substations

Engineering & Software

• Configurable via DIGSI 5 engineering tool
• Graphical logic configuration (CFC)
• Integrated protection, control, automation, and monitoring
• Simplified commissioning, testing, and diagnostics

Advanced / Latest Features (2024–2026 Update)

• Web-based user interface for remote monitoring
• Advanced cybersecurity:
  • Role-based access control (RBAC)
  • Secure firmware and communication
• Digital Twin support for simulation and testing
• Process bus ready (Sampled Values support)
• Power Quality monitoring (PQ Basic)
• PMU (Phasor Measurement Unit) functionality

Applications

• Feeder protection in MV/HV distribution networks
• Utility substations
• Industrial power systems
• Protection of:
  • Overhead lines
  • Underground cables
• Backup protection for transformers and other equipment