Question 1) Explain with the help of a neat sketch the construction working of a PWR. Write down its advantages and disadvantages?
Question 2)a) The motor of 30 h.p condensate pump has been burnt beyond economical repairs. Two alternatives have been proposed to replace it:
Motor A : cost Rs 1,50,000; η at Fullload= 90%; η at half load= 86%
Motor B : cost Rs 1,00,000; η at Fullload= 85%; η at half load= 82%
The life of each motor is 20 years and its salvage value is 10% of the initial coat. The rate of interest is 5% annually. The motor operates at full load for 25% of the time and at half load for the remaining period.
The annual maintenance cost of motor A is Rs 10500 and that of motor B is Rs 6000. The energy rate is Rs 2.50 per kwh. Which motor will you recommend?
b) The input_ output curve of a 60Mw power station is given by:
I = 106 (8 +8L +0.4L2) kcal/hour Where I is the input in kcal/hour and L is load in Mw
(i) Find out the heat input per day to the power station if it works for 20 hours at full load and remaining period at no load
(ii) Also determine the saving per kwh of energy produced if the plant works at full load for all 24 hours generating the same amount of energy
Question 3)a) synchronous motor improves power factor of a load from 0.7 to 0.9 lagging. The losses and other mechanical load on it amount to (250+200) kw, while the load for which power factor is considered is 1500kw. Determine the input to the synchronous motor and its power factor.
b) Starting from fundamentals obtain condition for maximum efficiency of a Power plant which has ‘n’ units to supply load.