THESE ARE THE QUESTIONS FROM THE SUBJECT POWER SYSTEMFUNDAMENTALS AND THE TOPIC IS MECHANICAL DESIGN OF OVER HEAD LINESAND THE ANSWERS ARE IN BRCKETS
1) Estimate the corona loss for a three-phase, 110 kV, 50 Hz,150 km long transmission line consisting of three conductors eachof 10 mm diameter and spaced 2·5 m apart in an equilateral triangleformation. The temperature of air is 30ºC and the atmosphericpressure is 750 mm of mercury. Take irregularity factor as 0·85.Ionisation of air may be assumed to take place at a maximum voltagegradient of 30 kV/ cm. [316·8 kW]
2). Taking the dielectric strength of air to be 30 kV/cm,calculate the disruptive critical voltage for a 3-phase line withconductors of 1 cm radius and spaced symmetrically 4 m apart. [220kV line voltage]
3). A 3-phase, 220 kV, 50 Hz transmission line consists of 1·2cm radius conductors spaced 2 m at the corners of an equilateraltriangle. Calculate the corona loss per km of the line. Thecondition of the wire is smoothly weathered and the weather is fairwith temperature of 20ºC and barometric pressure of 72·2 cm of Hg.[2·148 kW]
