In the following power system a directional comparison blocking scheme is to be used to protect line 1-2 and line 2-3. R

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In The Following Power System A Directional Comparison Blocking Scheme Is To Be Used To Protect Line 1 2 And Line 2 3 R 1 (46.85 KiB) Viewed 18 times

In the following power system a directional comparison blocking scheme is to be used to protect line 1-2 and line 2-3. Ru R o + 1+ j40.52 R2 2+j300 R21 25. pilot pilot - trip 7702 R2 is a directional mho relay providing primary protection to line 1-2 and R, is a directional mho relay which is to provide a blocking signal to R. Relays Ry and R, are to provide similar protection for line 2-3. Use 175% of the protected line impedance as the trip criterion. For the blocking signal use 160% of M -ZimeAssume the system voltage is 138-kV and the maximum load on either line is 120-MVA. (a) What are appropriate CT and VT ratios? I (b) What are the relay tripping settings (at the secondaries of the CT and VT) for R.R? (e) What are the relay blocking settings at the secondaries of the CT and VT) for R,R,,? (d) Draw an R-X diagram (at the secondaries of the CT and VT) for the line 1-2 relays and a second for the line 2-3 relays. Include the maximum load in both cases,