(a)
(b)
(c)
(d)
Figure 5: Structure and working principle of hybrid HVDC breaker. (a) Normal operation of hybrid HVDC breaker. (b) Short circuit fault occurs and LCS is blocked. (c) Fault current commutates to main switch and UFD is turned off. (d) IGBTs in main breaker are blocked and fault current commutates to arrestors’ branch.