Applications for direct light triggered thyristors with integrated protection functions

Direct light triggered thyristors (LTT) were developed for high voltage direct current transmission (HVDC) applications, because of the considerable advantage of high voltage blocking and the easy way of light triggering. Several protection functions were integrated in the LTT which are normally installed around the electrical triggered thyristor (ETT) by expensive and sensitive electronic components. LTTs are in use in applications with high voltage where a series connection of thyristors is necessary. For example HVDC, static VAr compensation (SVC), converters for medium voltage drives, and several pulse power applications.