Air-core reactors as fault limiting means on high interrupting capacity controllers

THE USE of air-core reactors as current-limiting means is very old and well established. They are used in large power networks for the protection of the generating equipment and the transmission system. Because of large currents in such networks, the reactors have very small inductances to avoid excessive voltage drops and are made of large conductors to keep losses within reasonable values. The electromagnetic forces, experienced during a fault, demand very rigid construction; consequently they often are embedded in concrete. If, however, reactors are installed in feeder or branch circuits where the normal currents are of much lower values, their inductances can be increased proportionately, limiting fault currents to lower values.