How D1816 Became the Standard for Dielectric Breakdown Testing

This is Part 3 of a seven-part series on dielectric breakage voltage testing in insulating transformer oils. Part 2 examined how each method responds to specific contaminant types and what drives variability in D1816 test results. Here we will cover the ASTM D1816 method — its capabilities, sensitivities, and the factors that drive result variability. Part 4 will examine D1816 sensitivity in detail — how the method responds to specific contaminant types and what drives result variability.

D1816’s Rise to Prominence

The shift away from ASTM D877 and toward D1816 was not gradual — it was significantly accelerated by the 2002 revision of IEEE Standard C57.106, Guide for the Acceptance and Maintenance of Insulating Oil in Equipment.¹ That revision removed D877 evaluation criteria for in-service transformer oil and introduced D1816 limits for both new and in-service oil, effectively establishing D1816 as the standard for mineral oil condition assessment in transformers.

The reason for this transition is straightforward: D1816 is measurably more sensitive than D877 to the contamination and degradation mechanisms that matter most in service — moisture, oil aging and oxidation byproducts, and particulate contamination, particularly insulation fibers.

How D1816 Works

ASTM D1816 uses spherical VDE (Verband Deutscher Elektrotechniker) electrodes and can be run at one of two gap settings: 1 mm (0.04 inches) or 2 mm (0.08 inches).² The increased sensitivity of the method relative to D877 is reflected in its lower voltage rise rate of 500 volts per second.

A motor-driven agitator runs throughout the test, directing oil flow between the electrodes and carrying suspended particles into the gap between the VDE spheres. This is a deliberate design feature — it ensures that particulate contamination present in the sample has the opportunity to influence the breakdown voltage result, rather than settling out of the measurement zone.

Original Scope and Expanded Application

Original Design Intent

D1816 was originally developed for equipment operating at primary voltage classes of 230 kV and above, where insulating oil had been processed with vacuum treatment and filtration prior to installation. The method’s sensitivity was calibrated for that context — highly processed oil in high-voltage equipment where even low-level contamination is consequential.

Expansion to Lower Voltage Classes

Over time, laboratories began applying D1816 to in-service oil from equipment well below the 230 kV threshold. The 2002 IEEE C57.106 revision formalized this expanded application by incorporating D1816 limits for a broader range of in-service equipment — acknowledging the method’s utility beyond its original design scope.

Adoption for Non-Petroleum Fluids

Although the ASTM standard designation specifies insulating oils of petroleum origin, D1816 has since been incorporated into standards governing other fluid types, including silicone and natural ester fluids. Its viscosity parameters do impose some application limits, but its sensitivity profile has made it the preferred dielectric breakdown voltage method across a widening range of insulating liquid types.

Summary:

• The 2002 revision of IEEE C57.106 was the inflection point that formalized the transition from D877 to D1816 for in-service transformer oil evaluation, introducing D1816 limits for both new and in-service oil.
• D1816 is more sensitive than D877 to moisture, oil aging and oxidation byproducts, and particulate contamination — particularly insulation fibers.
• The motor-driven agitator is a critical design element — it actively carries suspended particles into the electrode gap during the test, ensuring particulate contamination influences the result.
• Original scope was 230 kV and above, with vacuum-processed oil; expanded application to lower voltage classes and in-service oil was formalized through the C57.106 revision.
• Application has expanded beyond petroleum-based fluids — D1816 is now incorporated into standards for silicone and natural ester fluids, though viscosity parameters impose some limits.

References:

¹ “Guide for Acceptance and Maintenance of Insulating Oil in Equipment,” in IEEE Std C57.106-2002 (Revision of IEEE Std C57.106-1991), vol., no., pp.1-36, 8 Nov. 2002, doi: 10.1109/IEEESTD.2002.94145.

² Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using VDE Electrodes, ASTM D1816-12(2019), ASTM International, West Conshohocken, PA, 2019.

In This Series:

• Part 1: How Are Dielectric Breakdown Voltage Tests Standardized?
• Part 2: What Does ASTM D877 Actually Detect — and When?
• Part 3: How D1816 Became the Standard for Dielectric Breakdown Testing
• Part 4: How Do You Interpret ASTM D1816 Results Accurately?
• Part 5: How Do You Diagnose a Failed ASTM D1816 Result?
• Part 6: How Does ASTM D1816 Apply to New Insulating Oil?
• Part 7: How Does IEC 60156 Compare for Dielectric Breakdown Testing?