SG type isolation transformer,without case General (DG and SG series single-phase and three- ... 2.Altitude: <1000m 3.Relative humidity: <90% 4.Environment exists without gas, steam, chemical deposition, dust or dirt that will affect ... current. 6.Protection: over-current protection 7.Can operate itself without anybody attending for a long term 8.Insulation resistance: ≥50M ...