In this study, insulators and switchyard equipmentwith porcelain outer surface with the mostexperienced equipment failures in high voltagepower systems have been investigated. The effects ofthe external environment cause malfunctions inthese equipments are determined.Due to the external environment effects failuresoccurring in equipment were examined. Firstly,high-voltage switchgear equipments which are thesubject of study are explained. These include circuitbreakers, disconnectors, current transformers,voltage transformers, surge arresters and insulators,which have porcelain outer surface are counted.External environment pollution which is exposure ofthese devices is determined. Beach and industrialdirt, the dirt is separated into two parts. How causedpollution effects and dry dirt layer on the insulatorsurface by pollution factors explained. Then it wasdetermined, the dry dirt layer combined with themoist and rainy environment, creates surfaceleakage current on insulator surface and leakagecurrent is forming a dry band arcs. After, on theentire surface has been found to occur in theinsulator deformation with seen flashover. As aresult of these failures it was determined that theformation of power outages and financial loss.Different methods to reduce these defects occurringhave been proposed. These include porcelainsurface periodic manual cleaning, cleaning withabrasive spray, washing with water, heating theinsulator surface, design changes, use surfacecovering materials. The most effective among thesemethods the porcelain surface is coated with thesilicone coating material. Also, porcelain insulatorsto be replaced with silicon insulators necessity werelaid. The surface coating material impact andimplementation are described. With this method thesurface of the porcelain insulator to increase thehydrophobicity and whereby the surface leakagecurrents was intended the suppression.In order to emphasize the benefits of the proposedmethod within the scope of this article, operatingwithin the Turkey national electricity transmissionsystem in the Kaş district of Antalya province TEIAŞ154 / 31.5 kV Kaş substation and 154 kV Kaş-Fethiye power transmission lines was investigated.Kaş substation switchgear equipment (circuitbreakers, disconnectors, current transformers,voltage transformers, surge arresters, insulators)coated with a silicone coating material in june in2011 year and Kaş-Fethiye 154 kV powertransmission line porcelain insulators were replacedwith silicon insulators in the same year. The powerof transformer center which selected 50 MVA. Thelength of the transmission line 82 km and conductorgrade 477 MCM. Number of 154 kV line failureswhen before and after the maintenance worksoccurring has been compared with 48 in 2010, thework was completed in 2011 which fell to 5, thenumber of failures has been determined to occuramong 3 to 5 in subsequent years. If additional table1 and additional table 2 analyzed, distanceprotection relays of a large proportion of the faulthas been found to be phase ground fault. This showsthat due to the loading line overcurrent fault orphase-to-phase fault originating from theconductives contact to each other are not seen. Theequipment was contaminated under the influence ofenvironmental conditions and due to the coastalregion moisture has led to formation of discharge inthe transmission line which selected.Failure count becomes low, interruption time hasdecreased. After each failure occurred, transmissionline not becomes active. Because it needs to bereplaced damaged equipment during fault.Obtained results, the proposed method in this articlemethod shows that the implementation andperformance plays an important role in preventingpower outages that may occur in the transmissionlines.