A NEW LARGE-SCALE UNINTERRUPTIBLE POWER-SUPPLY (UPS) SYSTEM EMPLOYING GTO THYRISTORS

Progress in integrated circuit technology has made possible economical production of large capacity and high dielectric power semiconductors, such as gate turn-off thyristor (GTO) and power transistor. These semiconductors are ideal for use as an inverter because these elements possess a self-quenching function. NTT changed the main switching elements to GTOs insted of using reverse-blocking triode thyristors. Consequently, the elimination of commutation circuits, now makes possible the UPS system highly efficient, highly reliable and low cost. This paper describes the power semiconductor trend, choice of element and the outline of this new UPS system, employing GTOs.