Light-triggered thyristors for electric power systems, phase 2

Three devices were constructed with 5, 4, and 2 amplifying stages respectively with several subvariations (A, B, and C) of the two stage GE4 design proved sufficiently reliable for a one for one replacement of the normal, electrically triggered 2.6 kV HVDC cell. These devices proved the usefulness of the n(+) alignment band, a feature design to ensure even turn on, and the interrupted n(+) metal, a feature to enhance rapid spreading away from the initial turn on line. Important device characteristics other than a typical 160A microsec or better di/dt at 105 C and 1800 volts include the following: (1) typical forward breakdown voltage of 2900 volts; (2) typical reverse breakdown voltage of 3100 volts; (3) dv/dt capability of 2000V microsecond to 2200 volts; (4) forward drop at 105 C, 1000 amperes of 1.3 volts; and (5) a typical photo threshold of 10 to 20 nanojoules of incident photo energy. Surge capability and other device ratings are similar to the original electrically fired device.