Siemens SIPROTEC 5 7SL82 Line Differential & Distance Protection Relay

The Siemens SIPROTEC 5 7SL82 is a compact and cost-optimized numerical relay designed for combined line differential and distance protection in medium- and high-voltage power systems. It integrates advanced protection, control, automation, and monitoring functions into a single device, making it ideal for modern digital substations.

The relay uses an adaptive differential protection algorithm to ensure high sensitivity and stability even under challenging conditions such as CT saturation, transformer errors, and capacitive charging currents. It also offers multiple distance protection methods, allowing it to operate as both primary and backup protection.

With fast tripping capability, IEC 61850 communication support, and DIGSI 5 engineering, the 7SL82 provides reliable and flexible protection for overhead lines and cable systems. Its compact design and conformal coating make it suitable for harsh environments while maintaining high operational availability.

Main Function

• Combined line differential and distance protection
• Suitable for MV and HV overhead lines and cables
• Supports multi-end line protection (up to 6 line ends)
• Interoperability with SIPROTEC 4 and SIPROTEC 5 devices

Tripping

• 3-pole tripping
• Minimum tripping time: ~19 ms

Inputs and Outputs

• 4 current transformer (CT) inputs
• 4 voltage transformer (VT) inputs
• 11 or 23 binary inputs
• 9 or 16 binary outputs

Hardware Flexibility

• Compact hardware with fixed I/O configuration
• Multiple predefined I/O variants available
• No expansion modules (cost-optimized design)
• Configurable using the DIGSI 5 engineering tool

Housing

• Compact 1/3 × 19-inch housing
• Available with a small or large display
• Conformal coating for harsh environmental conditions

Function (Key Features)

• Adaptive differential protection for high sensitivity and stability
• Multiple distance protection methods:
  • Impedance-based
  • Reactance method (RMD)
• Directional backup protection
• Ground fault detection (including transient and harmonic methods)
• Fault locator for accurate fault distance calculation
• Power swing blocking for system stability
• Phasor Measurement Unit (PMU) functionality
• Basic power quality monitoring
• IEC 61850 communication with digital substation integration
• Cybersecurity features (role-based access, secure communication)