Over-current and earth fault protection and control


The GRE110 is a numerical multi-function protection device designed for feeder 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. This compact and cost-effective device can be applied not only as feeder protection but also as motor protection and back-up protection for generators and transformers.

  • • Protecting feeders and motors in medium voltage networks
  • • Backup protection for generators and feeders in high 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

All models include multiple, high accuracy, 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. A comprehensive range of additional protection functions are also supported, including thermal protection to IEC 60255-8, negative sequence overcurrent protection and a broken conductor detection feature, see Table 1. Control functions such as two-step operation of circuit. breakers are also provided.

Table 1 - GRE110 Models

Model Configuration
400: Three Phase Fault and Earth Fault
GRE110-400 2 x Bls and 4 x BOs
GRE110-401 6 x Bls and 4 x BOs
GRE110-402 6 x Bls and 8 x BOs
420: Three Phase Fault, Earth Fault and Sensitive Earth Fault
GRE110-420 2 x Bls and 4 x BOs
GRE110-421 6 x Bls and 4 x BOs
GRE110-422 6 x Bls and 8 x BOs

In addition, GRE110 provides multi-shot, three phase autoreclose, with independent sequences for phase fault, and earth fault and sensitive earth fault. Autoreclose can also be triggered by external protection devises.

All models provides continuous monitoring of internal circuits and of software. A trip circuit supervision function using two binary inputs provides high integrity monitoring of the circuit breaker tripping circuit breaker condition monitoring functions provide guidance of maintenance timing.

A user-friendly HMI is provided though 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 communications ports)

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