CHAPTER 9: THEORY OF OPERATION DISTANCE ELEMENTSD30 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 9-99Right Blinder Reach: 10 ΩNominal Secondary Voltage: 69.28 VRight Blinder RCA: 88°Distance Reach: 14 ΩLeft Blinder Reach: 5 ΩDistance RCA: 88°Left Blinder RCA: 88°Polarizing Current: Zero-sequenceNon-Homogeneity Correction Angle: 3°Directional RCA: 88°Z0/Z1 Magnitude: 4.55Overcurrent supervision: 3 AZ0/Z1 Angle: –12°Distance Comparator limit angle: 75°Z0M/Z1 Magnitude: 0Directional Comparator limit angle: 75°Assume that the following signals are injected to the relay:VA = 64.71 V ∠0.0° (pre-fault)VA = 25.43 V ∠–19.9°V B = 80.22 V ∠–133.5°VC = 77.33 V ∠135.7°IA = 4.47 A ∠–107.8°IB = 2.92 A ∠68.9°IC = 2.93 A ∠–51.1°Based on the entered setting the relay calculates:K0 = 3.58 ∠–15.2°K0M = 0Z = 14.00 Ω ∠88°ZD = 1 Ω ∠88°ZR = 9.99 Ω ∠−2°ZL = 4.99 Ω ∠178°For the assumed steady-state injection the relay calculates:VA_1 = 58.83 V ∠–2.1°VA_1M = 64.71 V ∠0.0°I_0 = 1.37 A ∠–68.2°IA_2 = 1.37 A ∠–68.1°–V_0 = 29.18 V ∠8.4°(VA –V B )_1 = 93.35 V ∠32.0°(VA –V B )_1M = 112.08 V ∠30.0°IA –IB = 7.39 A ∠–109.1°9.1.6.2 Mho phase A to ground element (before memory expires)IA × Z + I_0 × K0 × Z + IA × K0M × Z – VA = 103.33 V ∠–3.9°VA_1M = 64.71 V ∠0.0°IA _2 × ZD = 1.37 V ∠19.8°I_0 × Z = 19.11 V ∠19.8°I_0 × Z D = 1.37 V ∠19.8°
