Siemens Reyrolle 5 7SR51 Overcurrent & Feeder Protection Relay

The Siemens Reyrolle 5 7SR51 is a numerical protection relay designed for overcurrent and feeder protection in medium- and high-voltage power systems. It provides reliable protection, control, and monitoring functions, ensuring efficient and secure operation of electrical networks.

The relay supports both directional and non-directional overcurrent protection, enabling accurate fault detection in radial, ring, and interconnected systems. It is well-suited for protecting feeders, lines, and distribution networks, offering a flexible configuration to meet various application requirements.

In addition to protection, the 7SR51 integrates control and monitoring capabilities, allowing operators to manage circuit breakers and monitor system conditions in real time. Its user-friendly interface and flexible communication options make it easy to integrate into modern substation automation systems.

Main Function

• Overcurrent and feeder protection for MV/HV systems
• Suitable for radial, ring, and meshed networks
• Directional and non-directional protection schemes
• Integrated control and monitoring functions

Tripping

• Fast and selective 3-pole tripping
• Instantaneous and time-delayed overcurrent tripping
• Accurate fault isolation for improved system reliability

Inputs and Outputs

• Current transformer (CT) inputs: typically 3 or 4
• Voltage transformer (VT) inputs: optional (for directional protection)
• Binary inputs: configurable for control and status signals
• Binary outputs: configurable for tripping, alarms, and control

Hardware Flexibility

• Modular and flexible design
• Multiple configuration options for protection and control
• Expandable I/O depending on application needs
• Engineering and configuration using Reyrolle 5 software tools

Housing

• Compact and robust housing design
• Suitable for panel mounting
• Designed for reliable operation in industrial environments

Function (Key Features)

• Directional and non-directional overcurrent protection
• Earth fault protection (sensitive and directional)
• Time-delayed and instantaneous protection stages
• Thermal overload protection
• Breaker failure protection
• Auto-reclosing functionality (optional)
• Voltage and frequency protection
• Fault recording and event logging
• Integrated control of circuit breakers
• Communication support:
  • IEC 60870-5-103
  • Modbus
  • DNP3 (optional)
• Integration with SCADA and substation automation systems