With rapid industrialization the use of electrical machines is increasing exponentially. The use of these machines includes their application as continuous duty and intermittent duty. The intermittent duty applications have become very popular for their applications in automation, but assessment of power and power factor of such application has not been clearly defined, which has drawn attention of researchers in recent years. The paper discusses a method for assessment of power factor for intermittent duty load conditions. The method adopts the concept of energy losses corresponding to every power component (active, reactive, distortion and unbalance power) for the total period (light load period and heavy load period respectively). The discussion includes application for single phase and three phase unbalanced intermittent duty loads having harmonics, using the theory of symmetrical components followed by instantaneous reactive power theory (IRPT). Analysis is carried out mathematically and results are simulated under MATLAB.