The potential instrument transformers JDZ(X)11-15/20 are fully enclosed and cast in epoxy resin. The transformers are designed for electric power systems of rated frequency 50Hz/60Hz and rated voltage of 15/20 kV. They are used for indoor mounting. The performances of the products meet standards IEC60044-2 and GB1207-2006. The products are used in metering electric energy, voltage controlling and relay protection applications.