The Semikron SKKT 122/18E is a thyristor/thyristor module with 1.8kV, 129A and an A21 rating. It is a part of the SEMIPACK2 series, being a screw-mounted device. Thyristors are a type of specially-manufactured semiconductor, containing three or four layers of alternate p-type and n-type material. Once triggered, a thyristor can switch large amounts of current on or off without further control circuitry. The SKKT 122/18E is suitable for use in power control, motor control, and inductive heating applications.