Siemens SIPROTEC 5 7SA87 Distance Protection Relay

The Siemens SIPROTEC 5 7SA87 is an advanced modular distance protection relay specifically designed for protecting high-voltage transmission lines and complex power networks. Built on the powerful SIPROTEC 5 platform, it provides fast, selective, and highly reliable fault detection with both single-pole and three-pole tripping capabilities.

With its flexible modular architecture, the 7SA87 enables customized hardware configurations and supports a wide range of protection, control, automation, monitoring, and power quality functions in a single device. It is ideal for modern digital substations requiring high performance, scalability, and future-ready solutions.

The relay ensures ultra-fast fault clearing (as low as 9 ms), minimizing system disturbances and equipment damage. It also features advanced functions like Fault Locator Plus, adaptive protection schemes, and seamless integration with IEC 61850 communication protocols.

Main Function

• Distance Protection

Tripping

• 1-pole and 3-pole tripping (minimum ~9 ms)

 Technical Specifications

Protection & Functional Features

• Distance protection for transmission lines
• Detects:
  • Short circuits
  • Ground faults
• Backup protection for:
  • Line differential
  • Transformers, generators, and busbars
• Supports multiple protection methods:
  • Impedance (MHO)
  • Reactance method (RMD)
• 6 independent measuring loops for enhanced accuracy
• Fault Locator Plus for precise fault location
• Adaptive power swing blocking & out-of-step protection

Hardware & Modular Design

• Fully modular and expandable I/O configuration
• Available in multiple standard variants:
  • CT/VT: 4/4 or 8/8
  • Binary inputs: ~5 to 31
  • Binary outputs: ~8 to 46
• Flexible I/O structure within the SIPROTEC 5 platform
• Conformal coating for harsh environments
• Scalable for future system expansion

Communication & Protocols

• IEC 61850 Edition 2 compliant
• GOOSE messaging for high-speed communication
• Supports:
  • PRP / HSR redundancy
  • Modbus TCP, DNP3, IEC 60870
  • Up to 4 communication modules
• Enables full digital substation integration

Engineering & Software

• Configurable via DIGSI 5 engineering tool
• Graphical logic configuration (CFC)
• Supports protection, control, automation & monitoring in one device
• Simplified testing, commissioning, and diagnostics

Advanced / Latest Features (2024–2026 Update)

• Web-based access for diagnostics and monitoring
• Advanced cybersecurity:
  • Role-based access control
  • Digitally signed firmware
• Digital Twin support for simulation and testing
• Process bus ready (Sampled Values support)
• PMU (Phasor Measurement Unit) functionality
• Time synchronization via IEEE 1588

Applications

• High-voltage transmission line protection
• Complex power network protection (ring, mesh, multi-end lines)
• Utility substations
• Industrial power systems
• Backup protection for critical grid infrastructure