Petrochemicals, Energy | ASTM D2140 Carbon Type Composition of Transformer Oils - SVM 3001 and Abbemat Application Report

Determine the carbon type composition according to ASTM D2140 and viscosity parameters according to ASTM D3487 and IEC 60296.

1 Why measure viscosity and which other parameters are required for this application?

Transformer oils have two important functions: to be an electric insulator and to act as a coolant for the transformer. Effective cooling will increase the lifetime of the transformer, so the cooling liquid must be able to transfer as much heat as possible.

Viscosity and density at different temperatures are essential for the characterization of insulation oils. The standards IEC 60296 and ASTM D3487 specify such oils at different temperatures. These tests can be performed with the SVM 3001 fast and accurately.

Additionally, the carbon type composition is an important parameter for transformer oils. Critical product performance properties correlate with the carbon type composition. The Standard Practice ASTM D2140 (VGC-ri method; viscosity gravity constant - refractivity intercept) "Calculating Carbon-Type Composition of Insulating Oils of Petroleum Origin" is used to determine the carbon-type composition of insulating oils.

To calculate the carbon type composition of an oil, the following basic parameters are required: 

  • kinematic viscosity at 37.78 °C (100 °F) (obtained from SVM 3001)
  • refractive index at 20 °C (obtained from the refractometer)
  • density at 20 °C (calculated from API functions by the SVM software)
  • specific gravity at 15.56 °C (60 °F; calculated by API functions of the SVM software)

For determination of carbon type distribution according to ASTM D2140:

  • viscosity-gravity-constant (VGC) according to ASTM D2501, calculated from specific gravity (SG) at 15.56 °C (60 °F) and from kinematic viscosity at 37.78 °C (100 °F)
  • refractivity intercept (calculated from refractive index at 20 °C (68 °F) and from density at 20 °C (68 °F)

are required. These parameters are calculated by the SVM 3001 software.

This report describes specifically how to test oils with the SVM 3001 (according to ASTM D7042, D4052 and D2501) in combination with an Anton Paar Abbemat refractometer to get the carbon type composition according to ASTM D2140.

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