Siemens Reyrolle 5 7SR57 Motor Protection Relay

The Siemens Reyrolle 5 7SR57 is a numerical relay designed for advanced motor protection, ensuring safe operation during all motor starting and running conditions. It provides a comprehensive range of protection, control, and monitoring functions, making it ideal for medium- and high-voltage motor applications.

The relay features an advanced thermal protection algorithm that accurately matches motor characteristics, enabling precise thermal monitoring and preventing overheating. It also supports motor differential protection (87M) for enhanced protection of large and critical motors.

With support for up to 16 temperature sensors, the 7SR57 ensures detailed thermal supervision of motor systems.
In addition, it integrates communication, automation, and cybersecurity features, making it suitable for modern digital substations and industrial applications.

Main Function

• Comprehensive motor protection for MV and HV motors
• Suitable for all motor starting and running conditions
• Motor differential protection (87M) for large motors
• Thermal monitoring and overload protection

Tripping

• Fast and selective 3-pole tripping
• Accurate tripping based on thermal, differential, and fault conditions
• Prevents motor damage and operational downtime

Inputs and Outputs

• Current transformer (CT) inputs for motor current measurement
• Voltage transformer (VT) inputs for voltage-based protection
• Binary inputs: configurable for control and monitoring
• Binary outputs: configurable for trip, alarm, and control functions
• Supports multiple temperature sensor inputs (up to 16)

Hardware Flexibility

• Flexible configuration to suit different motor applications
• Wide operating range with minimal product variants
• Configurable thresholds and protection settings
• Easy integration with substation automation systems

Housing

• Compact and robust design
• Large LCD with intuitive user interface
• Withdrawable relay module for easy maintenance
• Designed for industrial and utility environments

Function (Key Features)

• Thermal overload protection with an adaptive algorithm
• Motor differential protection (87M)
• Overcurrent and earth fault protection
• Stall and start-up supervision
• Negative sequence (unbalance) protection
• Overvoltage / undervoltage protection
• Frequency protection
• Breaker failure protection
• Fault recording and event logging
• Power and energy monitoring

Communication & Integration

• IEC 61850 (Ed1 & Ed2) communication
• DNP3 TCP and Modbus TCP support
• Redundancy protocols:
  • PRP
  • HSR
  • RSTP
• Secure communication and cybersecurity features

Highlights

• Advanced thermal monitoring with up to 16 sensors
• Enhanced protection with motor differential (87M)
• High system availability with redundant communication
• Flexible and scalable for various motor applications
• Integrated protection, control, and monitoring