Substation Transformer Dissolved Gas Analysis Sampling Log

Inspection template for documenting transformer insulating oil sampling at substations for dissolved gas analysis (DGA) and dielectric testing, including sample location, collection conditions, chain of custody, and results tracked against established limits.

Inspection Identification

• Substation name and transformer identifier recorded
• Sample date and time recorded
• Sample location identified (bushing, drain valve, or designated sampling port)
• Reason for sampling documented

Safety and Isolation Controls

• Job hazard analysis or work permit completed
• Appropriate PPE worn for arc flash and oil handling hazards
• Transformer isolated and safe work boundaries established
• Sampling area free of active leaks, spills, or trip hazards

Sampling Method and Sample Integrity

• Sampling container was clean, sealed, and appropriate for laboratory analysis
• Sampling line or port flushed before collection
• Sample collected without visible contamination, moisture, or air bubbles
• Sample volume collected
• Sample bottle labeled with transformer ID, date, time, and sampler initials

Chain of Custody and Laboratory Submittal

• Chain-of-custody form completed
• Laboratory name and sample accession number recorded
• Requested tests selected

Laboratory Results and Limit Review

• Hydrogen (H2)
• Acetylene (C2H2)
• Total dissolved combustible gases
• Dielectric strength result
• Results reviewed against transformer-specific alarm limits and trend history
• Follow-up action required