We assume that the multifunction line relays are each
capable of providing BF protection. Fig. 9 and Fig. 10 present
the case where the bus relay is a multirestraint, low-impedance
type capable of providing BF protection. Fig. 11 shows the
bus relay as either a multirestraint type capable of integrating
the BF function or a high-impedance type not capable of
providing BF protection.