Question

An overhead line 300 km long and having surge inpedance loading of $100\Omega$. The line is open circuited at the receiving end and voltage of 500V is applied to the other end. Calculate the sending end voltage and current after 0.002 sec

• A. 500 V, -5A
• B. 1000 V, +5A
• C. 500 V, +5A
• D. 500 V, -10A

Answer 1

The correct option is A 500 V, -5A

Incident voltage V = 500 V

Incident current $I=\frac{V}{Z_c}=\frac{500}{100}=5A$

Time taken to reach 300 km

$T=\frac{300km}{3\times {10}^{5}km/sec}=0.001sec$

After 2T = 0.002 sec, voltage and current at sending end side are
$V_s=V=500V$
$I_s=-I=-5A$