《电路》（英文版）chapter 19 Problems

Basic Circuit Theory Chpter19 Problems At a frequency of 796 Hz, compute Zo r, u and a for a line having the following parameters: /2230 u H/km, c=0.0055 u F, r=6.46Q2/km, g negligible 2 At a certain frequency, a transmission line has Zo=553 260 Q2 and y=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 1000Q2 when viewed from the source. When open-circuited it appears as a capacitive reactance of 360Q2. Determine Z. and also the length of the line in wavelengths 4 At a frequency of 1000 Hz, a transmission line has Zo=500Z-37Q2 and y=0. 2245 Np/km. The line is 5 km long, in the load termination Z=400Q2, I=0.5A. Find the voltage and the current in the source termination 5 The transmission line is 70.8 km long, the following parameters: 0c=4x10-S, r=122, g=0 7=0. Find the voltage and the current in the start termination 6 A uniform line has r=7Q2/km, /=0.3 mH/km, c=0.2 u F/km, g=0.5x10 S/km at a frequency Of 800 Hz. Compute characteristic impedance Zo, propagation constant r,wave velocity u, and wavelength 1 Reference answers to Selected Problems 1:Z0=684∠-15°92,a=424×10-dB/m,B=18.2×103 rad/km,u=275×10-3kms, =345km 2(a)263∠-128V(b)0.177∠-154A 3:6009 DaLian Maritime University

Basic Circuit Theory Chpter19 Problems 1 At a frequency of 796 Hz, compute Z 0 γ ,u and λ for a line having the following parameters: l=2230 µ H/km, c=0.0055 µ F, r=6.46Ω /km, g negligible. 2 At a certain frequency, a transmission line has Z =553 and 0 ∠ Ω 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 1000Ω when viewed from the source. When open-circuited it appears as a capacitive reactance of 360Ω . 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∠ − Ω and o 37 γ =0.2 Np/km. The line is 5 km long, in the load termination Z =400 o ∠45 T Ω , 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− × Ω 6 A uniform line has r =7Ω /km, l = 0.3 mH/km, c = 0.2 µ 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 Ω 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: 600Ω . DaLian Maritime University 1