Phase controlled thyristor, stud type, also called "silicon controlled rectifier (SCR)", is used as non-contact switch and change DC to AC, widely applicable in fields of power supplies, motor control, AC switches, temperature controls and synchronous motor excitation etc. The stud type thyristor is classified as Phase Control Thyristor, Triacs, Avalanche Thyristors etc, mainly improved from I.R. Semikron & Russian-style and the metal stud structure and ceramic-metal stud structure both are available, which are characterized by superior surge capabilities. Its current is up to 500A.