Electrical insulating oils — standard tests for transformer oil Which of the following tests is generally not a standard requirement for transformer insulating oil?

Introduction / Context:
Transformer oil (mineral insulating oil) must provide dielectric insulation, cooling, and chemical stability. Routine tests assess properties tied directly to these functions to ensure safe operation of power equipment.

Given Data / Assumptions:

• Standard tests include dielectric strength, acidity, interfacial tension, moisture content, flash point, and sometimes corrosive sulphur.
• Aniline point is a solvent power indicator used for fuels; it is not central to transformer oil performance.

Concept / Approach:
Dielectric strength verifies insulation. Acid value tracks oxidation/aging. Flash point guards against fire risk. While copper corrosion or corrosive sulphur tests may be specified to avoid conductor damage, aniline point is not a typical transformer oil specification parameter.

Step-by-Step Solution:
Identify tests aligned with insulation and stability → flash point, acid value, dielectric strength, and corrosion-related tests apply.Aniline point does not correlate directly with dielectric performance or oxidation stability requirements.

Verification / Alternative check:
Utility specifications and ASTM/IEC standards focus on BDV, acidity, moisture, IFT, DGA, flash point, and corrosive sulphur—not aniline point.

Why Other Options Are Wrong:

• Flash point and acid value: routinely checked.
• Dielectric strength: fundamental electrical test.
• Copper corrosion (or corrosive sulphur): relevant for preventing copper conductor attack.

Common Pitfalls:

• Confusing fuel property tests with insulating oil requirements.

Final Answer:
Aniline point