Just to add further complexity to winnie's excellent description, the losses are also temperature dependant, increasing by about 0.4% per degree C over ambient. And you have to factor in the quality of the iron sheets used in the core laminations, because 'impurities', [carbon, phosphorus, sulphur, silicon, manganese, copper, etc.], affect permeability. Historically, many of these impurities could not be commercially totally removed from the iron in smelting, so pure ores were used; the best being pure red haematites from Sweden smelted with charcoal- because coal and derived cokes contaminated the metal. Hence the term Swedish Iron. Absolutely no idea what iron is used today though.
Alan
math error
[This message has been edited by Alan Belson (edited 12-05-2005).]
