Question 1:
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.
Question 2:
An industrial load takes 80,000 units in a year; the average power factor being 0.707 lagging. The recorded maximum demand is 500 kVA. The tagffis Rs 120 per kVA O fMaXimum demand plus 2.5 paise per kWh.
Calculate the annual cost of supply and find out the annual saving in cost by installing phase advancing plant costing Rs 50 per kVAR which raises the p.f. from 0.707 to 0.9 lagging. Allow 10% per year on the cost of phase advancing plant to cover all additional costs.