A single phase transmission line and a telephone line are both symmetrically strung one below the other, in horizontal configurations, on a common tower.  The shortest and longest distances between the phase and telephone conductors are 2.5 m and 3 m respectively. The voltage (volt/km) inducted in the telephone circuit, due to 50 Hz current of 100 amps in the power circuit is

A lightning stroke discharges impulse current of 10 kA (peak) on a 400 kV transmission line having surge impedance of 250Ω. The magnitude of transient over-voltage traveling waves in either direction assuming equal distribution form the point of lightning strike will be

A surge of 20 kV magnitude travels along a lossless cable towards its junction with two identical lossless overhead transmission lines. The inductance and the capacitance of the cable are 0.4mH and 0.5µF per km. The inductance and capacitance of the overhead transmission lines are 1.5mH and 0.015µF per km.  The magnitude of the voltage at the junction due to surge is

A lossless radial transmission line with surge impedance loading

A 132 kV transmission line AB is connected to a cable BC.  The characteristic impedances of the overhead line and the cable are 400Ω and 80Ω respectively.  Assume that these are purely resistive. A 250 kV switching surge travels from A to B.        

(a) Calculate the value of this voltage surge when it first reaches C.

(b) Calculate the value of the reflected component of this surge when the first reflection reaches A.

(c) Calculate the surge current in the cable BC.

An overhead line having a surge impedance of 400Ω is connected in series with an underground cable having a surge impedance of 100Ω. If a surge of 50kV travels from the line end towards the line-cable junctions, the value of the transmitted voltage wave at the junction is: