... 3 One year warranty 4 MOQ:1 set 3D H Grade insulation step down transformer Product introduction SGB9/10 ... also prevent short circuit. 1.Level H insulation: Dry-type tranformers have B, F, H, C, etc. hear insulation levels ... as major insulation material, having insulation level up to H and even C for the key part. 2.Safety: ... 11-2007; GB/T10228-2008; IEC60076-11 3D H Grade insulation step down transformer