717195.fig.004a
(a)
717195.fig.004b
(b)
Figure 4: The backward FTPN model of Figure 1 for fault at point (shown by place ). and correspond to the main protection, and CB1, , CB4, and correspond to the backup protection. (a) Information received from and CB2. is the firing sequence of sub-FTPN2. , , , , , . (b) Information received from CB2, CB1, , CB4, and . , , and are firing sequence of sub-FTPN1, sub-FTPN2, and sub-FTPN3, respectively, , , , , , , , , , , , , , , , .