The use of electrical power quality analyzers in industrial applications is essential in order to monitoring the features of the power electric used and determining which implications have in the process and the billing. However, those equipments require of a kind of setup to measure in steady state and other one when is required to measure transient phenomena. In this paper, a detection and isolation method of transient phenomena is developed, whose principal virtue is its simplicity compared with others options, derivative which, it is possible keep the measurements of steady state at the same time that the monitoring of transients, allowing having an integral knowledge of the electrical power quality.