Design a distance relay protection of the power system shown in Fig. 1 using a permissive underreaching transfer trip pilot scheme for lines A and B. Label the Line A relay at Substation 1 “21-Al”, the Line A relay at Substation 2 “21-A2”, the Line B relay at Substation 2 “21-B2”, and the Line B relay at Substation 3 “21-B3”. Show where each relay gets its potential and current inputs using the instrument transformers shown on Fig. 1. Also, show which breaker(s) is/are tripped by each relay. Be sure to describe the settings (in ohms) for zones 1, 2, and 3 of each relay. Describe how each of the four relays will respond to faults at locations W, X, Y, and Z. Further, explain what the relay response will be if the pilot communication fails.