... & SGPower Transformer,Dry type transformer,Three-phase Dry-type Power Transformer,Transformer,SG,DG DG and SG series Dry type ... proof and convenient maintenance,it can be applied to such power transmission and distributionplaces like underground railway,high building,airport, ... .Relative humidity:<90%4.Environnment exists with out gas,steam,chemical deposition,dust or dirt that will affect transformers ...