Digital T R a N S F O R M E R P Ro T E C T I O N F Ro M P Ower Plants to Distribution Substations

Traditionally, the protection of power transformers has been relegated to the application of transformer differential and backup overcurrent relays to provide shortcircuit protection. With the advent of modern multifunction transformer packages, differential and overcurrent protection are only two of many protective and logic functions that can be incorporated into the transformer protection package to enhance value to the user. Other protective functions include overexcitation protection (24), neutral overvoltage (59G), ground differential (87GD) and underfrequency (81U)/undervoltage (27) load shedding. Presently, many of these functions are handled via separate discrete relays or not applied at all because of economic considerations.