The FDGE11 semi-cast type discharge coil is vacuum cast in epoxy resin. The products are used for single-phase electric power systems of 50/60Hz rated frequency and rate d 12kV rated voltage, parallel connecting with high voltage capacitor group. The product can reduce the residual voltage of capacitor group to a safe voltage in 5 seconds after capacitor group is cut off from the electric system. When the coil is working normally, the secondary winding can act as voltage indicator. FDGE11 may be custom manufactured to combine residual voltage winding for protecting relay purpose. The products are used for outdoor mounting.