Low-impedance restricted earth fault (REF) protection protects transformer winding via earthed star-point. This paper compares the REF algorithms of five numerical relays: ABB's, AREVA T&D's, SIEMENS's, SCHNEIDER ELECTRIC's and GENERAL ELECTRIC's. Investigated were their advantages and disadvantages in speed, sensitivity, and selectivity. Also, magnetizing inrush current, over excitation, and CT saturation impression on REF operation, are presented. Postassessment, the results were confirmed via simulation on MATLAB SIMULINK. Further investigated were relay operation characteristic curves and restraint currents of each algorithm.
|Number of pages||17|
|Journal||Australian Journal of Basic and Applied Sciences|
|Publication status||Published - 1 Dec 2011|
- Low-impedance restricted earth fault
- Numerical relay
- Transformer protection