... 4.Apply for IEC,ANSI,GB. The three-phase oil-immersed distributing transformer applies new type insulating structure and makes short-circuit ... cost.---------------------------------product code (D: Single phase, S: three phase,F: ONAN Z: OLTC---------------------------------performance code (7, 8, 9, 10, 11, ... dry tropics TH: humid tropics) 6.6KV S9/S11 series oil immersed power transformer