Siemens SIPROTEC Compact 7SK80 Motor & Generator Protection Relay

The Siemens SIPROTEC Compact 7SK80 is a multi-functional numerical relay designed for comprehensive protection of asynchronous motors of all sizes, as well as small generator applications. It offers a wide range of protection, control, and automation features, making it suitable for both industrial and utility environments.

The relay includes flexible protection functionality, allowing users to configure up to 20 additional protection functions based on specific application requirements. This enables advanced protection schemes such as reverse power protection and frequency-based protection.

In addition to protection, the 7SK80 provides integrated circuit-breaker control, switching operations, and automation functions. With its built-in programmable logic (CFC), users can implement custom automation schemes such as interlocking and user-defined logic, enhancing operational flexibility.

The device also serves as an effective backup protection relay for transformer differential protection, with inrush suppression to prevent unwanted tripping. Its robust design, flexible configuration, and advanced communication capabilities make it a reliable solution for modern power systems.

Main Function

• Protection of asynchronous motors (all sizes)
• Protection of small generators
• Backup protection for transformer differential schemes
• Line protection for MV/HV networks

Tripping

• Fast and selective 3-pole tripping
• Protection-based tripping for overload and fault conditions
• Inrush suppression to avoid unwanted tripping

Inputs and Outputs

• 4 current transformer (CT) inputs
• 0 / 3 voltage transformer (VT) inputs
• 3 / 7 binary inputs (configurable)
• 5 / 8 binary outputs (including changeover contacts)
• 0 / 5 RTD inputs
• 1 life contact

Hardware Flexibility

• Expandable I/O using up to two SICAM I/O units
• Configurable via DIGSI
• Plug-in terminals for easy maintenance
• Integrated programmable logic (CFC)

Housing

• Compact housing with 6-line display
• 9 programmable function keys
• Front USB port
• Front-access battery replacement
• Designed for panel mounting

Function (Key Features)

• Overcurrent protection (51V)
• Intermittent & directional earth fault protection (67Ns)
• Restart inhibit (66/86)
• Over/undervoltage protection (27/59)
• Reverse & forward power protection (32)
• Power factor monitoring (55)
• Over/underfrequency protection (81O/U)
• ROCOF (81R) & voltage rate-of-change protection
• Negative sequence protection (46)
• Voltage unbalance monitoring (47)
• Start-time supervision (48)
• Breaker failure protection (50BF)
• Fault recording & event logging

Communication & Integration

• IEC 61850 GOOSE communication
• Ethernet with redundancy (RSTP, PRP, HSR)
• SNTP time synchronization
• Integrated Ethernet switch

Highlights

• Flexible protection with up to 20 additional functions
• Advanced automation via CFC logic
• Expandable I/O with SICAM modules
• High system availability with network redundancy