Complete the given question.
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 tariff is Rs 120 per kVA of maximum 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.