Normal Oil Level Range for OilImmersed Transformers

　　The normal oil level of an oilimmersed transformer is directly related to its load, ambient temperature, and tank structure (e.g., conservator type: diaphragm or expansion tank). Below is the technical specification based on industry standards (IEC 60076, GB/T 1094) and engineering practices:

　　1. Core Reference Basis

　　Oil level is measured via the oil level gauge (sight glass) on the conservator (expansion tank), which is marked with temperaturecorresponding scale lines (typically 30°C, 20°C, 40°C, 60°C). The normal range is defined as:

　　At rated load and ambient temperature (20°C): Oil level should be between the "20°C" marked line (midscale) and the "40°C" line (upper limit).

　　At noload or low ambient temperature (30°C to 0°C): Oil level may drop to the "0°C" or "20°C" line, but must not be lower than the "low oil level alarm threshold" (usually 510mm below the 30°C line).

　　At full load or high ambient temperature (40°C to 60°C): Oil level may rise to the "60°C" line, but must not exceed the "high oil level overflow threshold" (10mm above the 60°C line) to avoid oil leakage from the conservator’s breather or relief valve.

　　2. Key Limitations & Safety Thresholds

　　3. Supplementary Technical Notes

　　Conservator Function: The conservator compensates for oil volume expansion/contraction due to temperature changes. The normal oil level ensures the tank is fully filled with oil (no air gaps) while preventing overflow.

　　Oil Level Gauge Types:

　　Mechanical gauge: Marked with temperature scales; observe directly during operation.

　　Electronic gauge: Outputs oil level signals to the control system; alarms when exceeding normal range.

　　Exception Handling:

　　Sudden oil level drop: Inspect for leaks (tank welds, valve flanges, bushing base) and replenish qualified transformer oil (same brand/grade) if no leaks are found.

　　Abnormal oil level rise: Check for overheating (winding temperature, core temperature) or blocked oil circulation; eliminate faults before resuming operation.

　　This range ensures insulation performance (oil as dielectric and coolant) and equipment safety. Always comply with the manufacturer’s technical manual for modelspecific oil level requirements.