What Is the Neutralization Number?
The Neutralization Number quantifies the amount of potassium hydroxide (KOH) in milligrams required to neutralize the acidic constituents in 1 gram of transformer oil. It is expressed in mg KOH/g.
A rising acidity value is a red flag that the oil is deteriorating due to oxidation, contamination, or overheating.
Test Standard - IEC 60296
Fluids for Electrotechnical Applications – Unused Mineral Insulating Oils for Transformers and Switchgear
Oil Condition | Minimum BDV (kV) | Remarks |
---|---|---|
New oil | ≤ 0.01 | Excellent condition |
In-service oil | ≤ 0.10 | Acceptable |
Watch zone | 0.10 – 0.20 | Monitor closely |
Alarm condition | > 0.20 | Immediate attention recommended |


Why Acidity Testing Matters
- Detects early-stage oil aging
- Prevents sludge formation and clogging
- Minimizes corrosion of winding insulation and metal surfaces
- Helps optimize filtration or oil replacement schedules
- Improves asset life and reliability
Our Testing Process
Samples collected in vacuum-sealed bottles with barcode ID
Acid value measured via titration method in controlled environment
ERP-integrated data capture for consistency
AI-enhanced alerts for values outside tolerance
Reports delivered via dashboard or PDF
Tru-FIL Advantages
- IEC 60296 & ASTM-compliant lab procedures
- NABL-grade laboratory instrumentation
- Fully digital sample lifecycle from pickup to report
- Predictive maintenance insights using AI
- Nationwide collection & 24/7 operational support
Included in Your Report
- Measured Acidity (mg KOH/g)
- Comparison to standard limits
- Severity classification (Normal / Warning / Alarm)
- Comments on corrective actions (e.g., filtration, replacement)
- Historical trend (if available)