Necessary Steps for the Application of Gate Turn-off Thyristors in Inverters for Uninterruptible Power Supply Systems

Gate turn-off thyristors (GTOs) are more and more used in inverters for uninterruptible power supply systems (UPS). In the paper first of all the known advantages of the application of GTOs in UPS inverters are specified (losses, expenditure and noises). The paper considers in detail the special steps concerning dimensioning and protective measures that become necessary when using GTOs in UPS inverters. On the European market UPS systems have to be short-circuit-proof and have to deliver a high dynamic and static short-circuit current. This fact is the reason for the demand of high thyristor currents in proportion to the power of the equipment. The power range could be widened by parallel connection of GTOs. The results of respective investigations are represented.