The triggering state of the thyristor a

The triggering states of unidirectional and bidirectional thyristors are shown in Figure 1-13 (a) and
Figure 1-13 (b).
    In Figure 1-13, the potential polarity of the gate G is relative to the cathode K (unidirectional
thyristor) and the second electrode Tz ( bidirectional thyristor ). The sensitivities of the four triggering modes
    of bidirectional thyristors
are different. I+ and III- have high sensitivity, I- and III+
have low sensitivity, especially III+ has lower sensitivity. At present, many domestic components are not
suitable to use the III_ trigger method.