The IEC TS 62073 offers three ways to measure the hydrophobicity of insulator surfaces. The hydrophobicity describes how water-repellent a surface is. The methods proposed are a contact angle measurement, a surface tension measurement, and a spray method.

IEC TS 62073: Application and Use

The IEC TS 62073 deals with insulator surfaces, more specifically, the shed and housing material of composite insulators, for example used in overhead lines, substations, and ceramic insulators. Hydrophobicity describes how water-repellent a surface is. The hydrophobicity of insulator surfaces can change over time. This change can be due to ambient conditions as well as the chemical composition of the insulator.

IEC TS 62073: Experimentation

Apparatus

• For the contact angle method: a goniometer with a syringe or a computer-assisted device
• For the surface tension method: applicators (cotton-tipped, paintbrushes, or marker pens)
• The spray method: common spray bottle

All Contact Angle Meters, or Goniometers, of the OCA series from DataPhysics Instruments can perform the contact angle method.

Procedure

Three measurement methods are described in this standard in order to characterize the hydrophobicity of the material:

• Contact angle method: The standard makes a difference between measuring the static contact angle, measured on a horizontal surface, and the measurement of receding contact angles. The latter is performed using the so-called needle-in-method, in which the syringe/needle remains in the drop.
• Surface tension methods: This method is an extension of the IEC 60674-2, which deals with the determination of the surface tension of films. In the IEC TS 62074, different organic liquid mixtures (cellosolve/formamide, distilled water/formamide, distilled water/sodium chloride) with increasing surface tension are used for measurement. The time elapsed from the application to the formation of droplets gives an indication if a mixture with higher surface tension should be used or not. The aim is that the liquid mixture does not form drops but remains as a continuous coverage within a certain time period.
• The spray method: Water is sprayed on the surface using the spray bottle. The resulting drop-formation is then compared to the seven hydrophobicity classes described in the standard.

The IEC TS 62073 is in use since 2016.

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