IEEE C57.120-1991 pdf free.IEEE Loss Evaluation Guide for Power Transformers and Reactors.
IEEE C57.120 cost rates, in dollars per kilowatt,for no-load,load, and auxiliary losses,asfound in 6.2.1,6.2.2 and 6.2.3, respectively, are the figures that should be furnished to themanufacturers at the time of soliciting bids.
The manufacturer may utilize the cost rate values to build a transformer that hasamounts of conductor and iron that are economically dictated by the dollar evaluation.That is, the manufacturer may reduce losses, by adding conductor and iron up to anamount where the incremental construction costs of adding conductor and iron equal theincremental value of the transformer.
The rates should be preferably furnished to the manufacturers in the dollars-per-kilo-watt form as discussed above. They may also be given in the levelized annual form ofdollars-per-kilowatt-year, but if they are so given, it will be necessary also to supply themanufacturer with information as to the purchaser’s fixed charge rate，sales tax rate,overheads, etc., and to rely on the manufacturer to make the proper calculations.Use of thedollars-per-kilowatt form will ensure that each manufacturer is using the same basis foroptimizing the design.
In order to compare two or more bids, add the following products to the bid price (for eachseparate bid):
(1) The manufacturer’s guaranteed no-load losses in kilowatts,times the dollars-perkilowatt figure for NLLCR.
(2)The manufacturer’s guaranteed load losses in kilowatts，times the dollars-perkilowatt figure for LLCR.
(3)The manufacturer’s guaranteed losses for each type of auxiliary loss,times the appropriate dollars-per-kilowatt figures for ALCR1,ALCR2,etc.
When all of these are added to the bid price, the lowest resulting figure indicates the “bestbuy,”provided, of course, that the offered transformers are comparable in other respects.if loss evaluation figures are furnished to the manufacturers at the time of solicitingbids, the steps outlined above should be used to select the best offering. A selection basedonly on bid price will not necessarily represent the true value of the offered equipment.IEEE C57.120 pdf download.