Basic Circuit Theory Chpter19 Problems 1 At a frequency of 796 Hz, compute Z 0 u,γ and λ for a line having the following parameters: l=2230μ H/km, c=0.0055μ F, r=6.46? /km, g negligible. 2 At a certain frequency, a transmission line has Z =553 and 0 ?∠ o 60 γ =0.005 + j0.03 Np/km. The line is 60 km long. A sinusoidal voltage of 100V at the specified frequency is applied to one end. Find: (a) the voltage at the termination, if open-circuited; (b) the current at the termination, if short-circuited. 3 A lossless line, when short-circuited at the termination, is found to have an inductive reactance of 1000? when viewed from the source. When open-circuited it appears as a capacitive reactance of 360? . Determine Z , and also the length of the line in wavelengths. 0 4 At a frequency of 1000 Hz, a transmission line has Z 0 =500 and ??∠ o 37 γ =0.2 Np/km. The line is 5 km long, in the load termination Z =400 o 45∠ T ? , I =0.5A. Find the voltage and the current in the source termination. T 5 The transmission line is 70.8 km long, the following parameters: ω c=4 S, r =1 , g = 0, l = 0. Find the voltage and the current in the start termination. 4 10 ? × ? 6 A uniform line has r =7? /km, l = 0.3 mH/km, c = 0.2μ F/km, g = 0.5 S/km at a frequency 0f 800 Hz. Compute characteristic impedance Z 0 , propagation constant 6 10 ? × γ , wave velocity u, and wavelength λ . Reference Answers to Selected Problems 1: Z =684 , 0 o 15?∠?α =42.4 dB/km, 3 10 ? × β =18.2 rad/km, u=275 km/s, 3 10 ? × 3 10 ? × λ =345 km. 2: (a) 263 V; (b) 0.177 A. o 128?∠ o 154?∠ 3: 600 . ? DaLian Maritime University 1