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.