Motor protection

Motor Protection – Reyrolle 7SR105

Reyrolle 7SR105

Reyrolle 7SR105 Rho motor protection relay is a numerical protection relay intended for use in the motor protection applications. It provides a highly comprehensive functional software package with a range of integral application functions aimed at reducing installation, wiring, and engineering time.

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Features & functions

Motor protection Reyrolle 7SR105


The device is housed in a 4U high, size 4 non-withdrawable case and these relays provide protection, monitoring, instrumentation, and metering with integrated input and output logic, data logging and fault reports. Communication access to the relay functionality is via a front USB port for local PC connection or rear electrical RS485 port for remote connection. 

A wide range of measured values can be viewed on the front LCD or remotely via the communications channel. The integrated control feature allows the safe operation of a motor and monitoring its start and stop operations.


  • Optional RTD inputs

  • Cold load settings

  • Two settings groups

  • Password protection

  • Self-monitoring

  • Circuit breaker trip counter

  • Fault, event and waveform records

Bruce Watson presents the motor protection devices Reyrolle 7SR105 and Reyrolle 7SR17


Protection functions

  • Stall protection (14)

  • Undercurrent (37)

  • Current unbalance protection (46)

  • Phase reversal (46Ph Rev)

  • Start protection (48/66)

  • Motor thermal overload (49R)

  • Time-overcurrent protection (50/51)

  • Earth fault (50/51G/N)

  • Backspin protection (81B)

  • Temperature inputs (RTD)

Supervision functions

  • Circuit breaker fail (50BF)

  • CT supervision (60CTS)

  • Trip circuit supervision (74T/CCS)

Monitoring functions

  • Instrumentation