Transformer Protection


The GRE160 is a fully numerical multi-function transformer protection device designed for two-winding transformer protection applications, drawing on proven technologies developed over more than 100 years, and providing a comprehensive range of protection and control functions.

  • • Protecting two-winding transformer
  • • Current differential protection and comprehensive backup protection including overcurrent and earth fault protection, restricted earth fault protection, overexcitation protection etc.
  • • Feeder manager device with 2 x 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

GRE160 has five models which differ according to the number of analogue inputs provided for backup protection functions for the 2-winding transformer protection.

For each model, there are three different types which differ depending on the number of binary inputs and outputs provided. Combined 1A/5A current inputs and wide auxiliary supply voltage ranges simplify type selection. (See Table 1)

All models include the current differential protection element which has both 2nd/5th harmonic restraint features. The 2nd harmonic restraint feature is provided to avoid unnecessary tripping due to inrush current during transformer energization and the 5th harmonic restraint feature can be used to block the operation of the relay during transient power system disturbances. Multiple, high accuracy, overcurrent and earth fault protection elements with inverse time and definite time delay functions are provided in accordance with the IEC 60255-151 functional standard. A comprehensive range of additional protection functions are also supported, including thermal protection in accordance with functional standard IEC 60255-149 negative sequence overcurrent protection and circuit breaker failure protection.

When models equipped with the voltage input are chosen, overexcitation protection, over/under voltage protection, frequency protection and voltage controlled overcurrent protection are available.

Control functions including the two-step operation of circuit breakers are also provided.

Table 1 - GRE160 Models

Model 100 2 three-phase current inputs
Model 200 2 three-phase and 2 zero-phase current inputs for restricted earth fault protection
Model 300 2 three-phase current inputs and 1 single-phase voltage input for voltage, overexcitation, frequency, voltage controlled overcurrent protections
Model 400 2 three-phase and 2 zero-phase current inputs and 1 single-phase voltage input
Model 500 2 three-phase and 2 zero-phase current inputs and 1 set of three-phase and zero-phase voltage inputs
Type Configuration
GRE160-*00 6 x Bls, 4 x BOs and Fail BO
GRE160-*01 12 x Bls, 10 x BOs and Fail BO
GRE160-*02 18 x Bls, 16 x BOs and Fail BO

where * represents the model number from 1 to 5

All models provide continuous monitoring of internal circuits and software. A trip circuit supervision function using two binary inputs provides high- integrity monitoring of the circuit breaker tripping circuit in both the circuit breaker open and closed conditions. Circuit breaker condition monitoring functions provide guidance in planning the optimum time for maintenance.

A user-friendly HMI is provided through a backlit LCD, programmable LEDs, keypad and menu-based operating system. PC access is also provided, either for local connection via a front-mounted USB port, or for remote connection via a rear-mounted RS485 port or an optional Ethernet port. The communication system allows the user to read and modify the relay settings, and to access data gathered by the metering and recording functions provided within the relay.

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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