Motor Protection and control


The GRE120 is a fully numerical multi-function protection device designed for motor protection applications in MV networks, drawing on proven technologies developed over more than 100 years, and providing a comprehensive range of protection and control functions. The GRE120 supports multiple, high accuracy motor protection elements such as thermal protection based on the IEC 60255-8, motor status monitoring, locked rotor protection and restart inhibit as well as supporting protection and control functions.

  • • Protecting motor and feeders in medium voltage networks
  • • Feeder manager device with CB control function, 43R/L switch and comprehensive supporting functions
  • • Compact and cost-effective design
  • • Elementary, environmentally-friendly, easy to use and enhanced product concepts

There are two models which differ in number of binary inputs and outputs, see Table 1. Combined 1A/5A current inputs and wide auxiliary supply ranges simplify type selection.

Table 1 - GRE120 Models

Model Configuration
400: Three Phase Fault and Earth Fault
GRE120-400 2 x Bls and 4 x BOs
GRE120-401 6 x Bls and 4 x BOs

All models include multiple, high accuracy motor protection elements such as thermal protection based on IEC 60255-8, motor status monitoring, locked rotor protection, restart inhibit and temperature calculation on current basis. A comprehensive range of additional protection functions are also supported, including overcurrent protection elements (for phase and/or earth fault) with inverse time and definite time delay functions, in accordance with the IEC 60255-151 functional standard, negative sequence overcurrent protection and a broken conductor detection feature. Control functions such as two-step operation of circuit breakers are also provided. The overcurrent protection characteristics change with motor status (start-up / running).

GRE120 provides continuous monitoring of internal circuits and of software. A trip circuit supervision function using two binary inputs provides highintegrity monitoring of the circuit breaker tripping circuit in both the breaker open and closed conditions. Circuit breaker condition monitoring functions provide guidance of maintenance timing.

A user-friendly HMI is provided through a backlit LCD, programmable LEDs, keypad and menu-based operating system. PC access is provided for local connection via a front-mounted USB port. The communication system allows the user to read and modify the relay settings, and to access data gathered by the relay's metering and recording functions.

Data available either via the relay HMI or communications ports includes the following functions.

  • Metering
  • Fault recording
  • Event recording
  • Disturbance recording (available via USB port)

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