For SF6 gas used in electrical equipment (GIS, circuit breakers, transformers, etc.), the acceptable dew point is defined by international standards and manufacturer requirements. The key values are as follows:
• New gas (unused): ≤ −40 °C
• In-service gas: typically ≤ −30 °C to −25 °C
• For critical GIS applications: often required ≤ −40 °C
Explanation:
• A low dew point ensures that no condensation forms inside the equipment, which could cause internal flashover or corrosion of metal parts
• IEC 60480 specifies the water content limit for new SF6 gas, which corresponds to a dew point of approximately −40 °C.
• Utilities and manufacturers often impose stricter in-service limits to maintain reliability.
If you need, I can also provide the corresponding water content (ppm) for these dew points.