standards / manuals / guidelines for small hydro development - AHEC

Rationalization of capitalization Formula for Transformer LossesAnnexure-3.2The rated capitalization of transformer losses depends upon the rate of interest, rate of electricalenergy per kWh, life of transformer and average annual loss f actor. The annual loss factor takesinto account the loading of the transformer during the year. In computing the rate ofcapitalization of iron losses, copper losses and auxiliary losses. Following assumptions arerecommended.(i)(ii)(iii)(iv)(v)(vi)Rate of interest (r):Rate of electrical energy (EC): It is the cost of energy per kWh at the bus to which thetransformer to be connected.Life of the transformer (n): It is taken 25 years.Life transformer is in service for a period of 350 days in a year (allowing 15 days formaintenance, breakdown, etc.).The cooling pumps remain in service for 40% of the time, the transformer is in service.Annual loss factor: The annual loss factor may be worked out on the basis of the formulagiven below.LS = 0.3LF + 0.7 (LF) 2Where:LS is the annual loss factorLF is the annual load factorAssuming annual load factor as 60%, annual loss f actor works out to 0.432.Capitalization Formula SuggestedCapitalised Cost of Transformer = Initial cost + Capitalised cost of annual iron losses +Capitalised cost of annual copper losses + Capitalisedcost of annual auxiliary losses.Capitalised cost of iron losses per kW = 8400EC n1r 1r1 r nCapitalised cost of copper losses per kW = 8400EC n1r 1LSr1 r nCapitalised cost of iron losses per kW = 0.48400EC n1r 1r1 r nSubstituting the values, the capitalized cost of transformer.Actual value can be worked out by the purchaser by considering appropriate value of r, E L , L F ,and L C .3-17