부산대학교 도서관

Symmetric thyristors with blocking voltages of 2.5 kV have been evaluated under high current conditions in circuits where a reverse voltage is applied to the SCR, caused by a load mismatch in the pulse forming network. The 50 mm diameter SCR was operated in a 45 m/spl Omega/ PFN with a 12.5 m/spl Omega/ load and a shorted load. The peak current switched with the 12.5 m/spl Omega/ load at 1.5 kV was 25.2 kA. The inverse voltage applied to the device was -740 V which was preceded by a voltage spike of 2.2 kV. This spike has a pulse width of 2.5 /spl mu/s and a dv/dt, measured at the 10%-90% points of 875 V//spl mu/s. With the load shorted and an anode voltage 1.4 kV, 29.2 kA was switched with a pulse width of approximately 600 /spl mu/s. The 2.8 /spl mu/s reverse voltage spike under these conditions had a peak voltage of -2.5 kV, a dv/dt of 1.2 kV//spl mu/s and a recovery voltage of -1.1 kV. Data is also presented on 3 SCRs operating in individual PFNs connected in parallel discharging into a common load. This simulates switches operating in the phases of a rotating machine. Data on the characterization and inverse voltage operation of new GE 100 mm SCRs are also presented.