A factory takes a steady load of 200 kW at a lagging power factor of 0·8. The tariff is Rs 100 per kVA of maximum demand per annum plus 5 paise per kWh. The phase advancing plant costs Rs 500 per kVAR and the annual interest and depreciation together amount to 10%.
Find:
(i) the value to which the power factor be improved so that annual expenditure is minimum
(ii) the capacity of the phase advancing plant
(iii) the new bill for energy, assuming that the factory works for 5000 hours per annum.