Question: A (345-mathrm{kV}), three-phase transmission line has a 2.2-kA continuous current rating and a (2.5-mathrm{kA}) maximum short-time overload rating with a (356-mathrm{kV}) maximum operating voltage. The

A \(345-\mathrm{kV}\), three-phase transmission line has a 2.2-kA continuous current rating and a \(2.5-\mathrm{kA}\) maximum short-time overload rating with a \(356-\mathrm{kV}\) maximum operating voltage. The maximum symmetrical fault current on the line is \(30 \mathrm{kA}\). Select a circuit breaker for this line from Table 7.10.

Table 7.10

Identification Nominal Voltage Class (kV, rms) Col 1 14.4 14.4 23 34.5

Identification Nominal Voltage Class (kV, rms) Col 1 14.4 14.4 23 34.5 46 69 115 115 115 115 115 115 138 138 138 138 138 138 138 138 161 161 161 161 230 230 230 230 230 230 345 345 500 500 700 700 Nominal Rated Max 3-Phase MVA Class Col 2 250 500 500 1500 1500 2500 Not Applicable Voltage (kV, rms) Col 3 15.5 15.5 25.8 38 48.3 72.5 121 121 121 121 121 121 145 145 145 145 145 145 145 145 169 169 169 169 242 242 242 242 242 242 Voltage 362 362 550 550 765 765 Rated Voltage Range Factor (K) Col 4 2.67 1.29 2.15 1.65 1.21 1.21 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Rated Values Insulation Level Rated Withstand Test Voltage Low Frequency Impulse (kV, rms) (kV, Crest) Col 5 Col 6 Rated Rated Continuous Short-Circuit Current Current at 60 Hz (Amperes, rms) Col 7 600 1200 1200 1200 1200 1200 1200 1600 2000 2000 3000 3000 1200 1600 2000 2000 2000 3000 3000 3000 1200 1600 2000 2000 1600 2000 3000 2000 3000 3000 2000 3000 2000 3000 Current 2000 3000 at Rated Max kV (kA, rms) Col 8 8 18 11 22 17 19 20 40 40 3 40 3 20 40 40 63 80 40 3 0 16 31 40 50 31 31 31 40 40 3 40 40 40 40 40 40 8.9 63 63 63 80 31.5 31.5 31.5 31.5 63

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