What are the limits in dissolved gas analysis of transformer oil?

Limits vary, but safe thresholds (per IEEE/IEC) are: H? < 150 ppm, CH? < 120 ppm, C?H? < 35 ppm. High levels indicate arcing, overheating, or insulation faults. DGA should be paired with oil purification (e.g., Fluidex) to prevent fault progression.