Power station 16

 Question =  the annual load duration curve of a certain power station can be considered as a straight line from 20 MW to 4 MW . To meet this load three turbine generator units , two rated at 10 MW each and one rated at 5 MW are installed determine (1) installed capacity (2) plant factor , (3) units generated per annum , (4) load factor , (5) utilisation factor . 

Solution = (1) installed or plant capacity = 10 + 10 + 5 = 25 MW , answer ✓ 


(2) plant factor = average demand ÷ plant capacity , 

» Referring to the load duration curve , = average demand per unit = 1/2 (20 +4 ) , = 12 MW per unit , 

» so , P.F. = 12 MW ÷ 25 MW , = 0.48 , for % = × 100 , = 0.48 × 100 , = 48 % ,  answer ✓

(3) unit generated per annum = area ( in kWh ) under load duration curve , = 1/2 ( 4000 kW+ 20,000 kW ) × 8760 hours , = 105.12 ×10⁶ kWh , answer ✓ 

(4) load factor = average demand ÷ maximum demand , 

» L F. = 12 MW ÷ 20 MW = 0.6 , 

» for % = × 100 , = 0.6 × 100 = 60 % , answer ✓ 

(5) utilisation factor = maximum demand ÷ plant capacity , 

= 20 MW ÷ 25 MW , = 0.8 , or , for % = × 100 , = 0.8 × 100 , = 80% , answer ✓ 

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