Siemens SIPROTEC Compact 7SJ80 Overcurrent & Feeder Protection Relay

The Siemens SIPROTEC Compact 7SJ80 is a numerical relay designed for directional and non-directional overcurrent protection in medium- and high-voltage networks. It provides reliable protection, control, and monitoring functions, ensuring fast and selective fault isolation in distribution systems.

The relay is suitable for protecting feeders, lines, and distribution networks operating in radial, ring, and meshed configurations. With its advanced protection features, it ensures dependable detection of short circuits, overloads, and earth faults, minimizing system disturbances and equipment damage.

In addition to protection, the 7SJ80 supports control and automation functions, making it a versatile solution for both utility and industrial applications. Its integration capabilities with substation automation systems ensure efficient and reliable operation of modern power networks.

Main Function

• Overcurrent and feeder protection for HV and MV networks
• Suitable for radial, ring, and meshed systems
• Directional and non-directional protection schemes
• Backup protection for transformers, generators, and motors

Tripping

• Selective 3-pole tripping
• Instantaneous and time-delayed tripping characteristics
• Fast fault clearing for improved system stability

Inputs and Outputs

• Current transformer (CT) inputs: typically 4
• Voltage transformer (VT) inputs: up to 4 (for directional protection)
• Binary inputs: configurable for status and control
• Binary outputs: configurable for tripping, alarm, and control

Hardware Flexibility

• Modular design with configurable I/O
• Flexible application configuration using DIGSI
• Expandable depending on application requirements
• Supports multiple communication modules

Housing

• Available in 1/3 × 19-inch and other housing variants
• Panel or flush mounting options
• Rugged design suitable for industrial environments

Function (Key Features)

• Directional and non-directional overcurrent protection
• Time-delayed and instantaneous overcurrent stages
• Directional earth fault protection
• Sensitive ground fault detection
• Thermal overload protection
• Breaker failure protection
• Auto-reclosing (optional)
• Voltage and frequency protection functions
• Fault recording and event logging
• Communication support:
  • IEC 60870-5-103
  • Modbus
  • PROFIBUS (optional)
• Integration with substation automation systems