Draw a block diagram to express following coupled differential equations with no differentiators. (u1 and u2-input, y=output, x-state variable and a, b1, b2, c, d1, d2=constant) dx/dt=ax+blu1+b2u2 dy/dt=cx+d1u1+d2u2e

A) Explain earthing and its importance in electrical installation. BÍ With a help of a labelled diagram a single phase supply, differentiate between TN-S earthing system and TN-C-S system. C Calculate the earthing resistance of an electrode given its length is 4 dm and its radius of 1 cm if the resistivity of the soil is 50 ohms. D) From the result obtained in the question 2(C), calculate the earth resistance when two similar electrodes are in parallel. Explain your answers.

14. For a power plant with two units, the weekly load is 1200 MW. The coal consumption (tons/hour) for each unit is Q₁ 16+.3P₁ tons/hours Q2-25+.4P₂ tons/h The total coal available to the plant is limited to 90,000 tons/week. If the linear cost curves are given as C₁=495+11P₁ $/hour, C₂-760+10P₂ $/hour And generation by each unit is limited to 150 ≤ P, ≤ 600MW Determine the values of P₁ and P₂ for minimizing the cost of power generation. 15. Use LP to determine economic dispatch if C₁ = 5+ 3P₁, C₂ = 7+6P2, C3 = 8 + 9P3 50 P₁ < 150 MW and PD=210 MW If the line flow P12= .3P₁ + .4P₂ + .1P3, also determine P₁, P₂ and P3 so that P₁2 is limited to 70 MW. 1 4 400 ≤ P₂ ≤1000MW H 2 3

21. A piece of wire that is one mil in diameter and one foot long is one mil-foot.   Select one: TRUE FALSE