Comparison of approaches with an account of powers

There are discussed limits of correct appliance of multipliers such as complex conductivity and resistances in power calculations. It is revealed that Budeanu method which uses them is accurate only in those conditions when they substitute the system matrix of state equations correctly. The correctness is complied with the coincidence of currents with eigenvectors of state matrices. Being more universal Fryze method is simple in practical realization in the conditions of modern digital form of measurement information.