This article presents a study of Quality of Electric Power in an electricity concessionaire performed in 2015 at a substation media tension with 13.8 kV voltage level. The purpose of this article is to measure and monitor for a period of seven days the supply of electricity in the CAP (Common Coupling Point) in the electrical system bus of Dealers and analyze what the real situation of electricity supply for the consumer units, based on criteria established by the IEC TR 61000-3-6, IEEE 519-92 and PRODIST / ANEEL. The methodology used for this work was through field measurements. To carry out campaigns of field measurements was used the Quality Analyzer HIOKI PW3198 Power. The results of the obtained analyzes showed that the presented methodology is applicable as the new requirements associated with power quality come into force, among which may be mentioned harmonic distortion, SAG, SWELL, which will be charged to companies power distribution, ie electricity distributors must conform to such requirements by PRODIST / ANEEL, otherwise companies will suffer penalties by large fines.