Page 129 - Power Electronics Handbook
P. 129
122 Power semiconductor protection
A Load
B
'LOAD
'THl
',ti*
(C)
Figarc 5.1 Effect of component failure in power circuits: (a) forced commutated circuit; (b)
naturally commutated circuit; (c) wavefonns for naturally commutated circuit
Figure 5.1 illustrates the effects of component-related failure in two
common circuits. In Figure 5.l(a) thyristor THl is the main load-carrying
device and thyristor TH2 is an auxiliary component, which discharges
capacitor C1, causing the main thyristor to turn off. Diode D1 is a
free-wheeling device placed across the load, to carry the inductive load
