EN/IEC 60112 Method for Determining Proof of Solid Insulation Materials and Comparative Tracking Indexes

The IEC 2020 standard, the basis of which is a European standard and the last update of which was published in 60112, was prepared by the International Electrotechnical Commission (IEC). This standard provides a test method for determining the proof and comparative tracking indices of solid insulating materials on parts and material plates taken from equipment using alternating voltage. This standard is also used to determine erosion when necessary.

The aforementioned standard has been published by the Turkish Standards Institute (TSE) in our country with the following title: TS EN IEC 60112 Solid insulation materials - The method of comparison and determination of durability indices related to surface leakage.

The tracking index determined by the test method presented is an important tool for quality control of materials and fabricated parts. It is also used as an acceptance criterion. The comparative tracking index is mainly used for the basic characterization of materials and comparison of their properties.

This test method evaluates both the surface properties of the material under consideration and the composition of the material. Both composition and surface condition directly affect the results of the assessment and are taken into account when using the results in the material selection process.

However, the test results are not considered suitable for the evaluation of safe leakage distances when designing electrical apparatus.

This test method distinguishes between two groups of materials for use in equipment used under humid conditions:

• Materials with relatively poor resistance to tracking
• Materials with medium or good resistance

Meanwhile, there are longer-term and more rigorous test methods for evaluating the performance of materials for outdoor use using higher voltages and larger test samples. For example, the IEC 60587 standard provides test methods for monitoring and evaluating resistance to erosion for electrical insulating materials used in severe ambient conditions.

The important technical changes made in the last update compared to the previous version are:

• Introducing a new contaminant solution C with a surfactant that complies with the test method of the IEC 60587 standard
• Introducing a screening test, taking into account the fact that some materials can withstand high test voltages but fail at lower test voltages

Briefly, the IEC 60112 standard is used to evaluate the relative resistance of insulating materials to tracking. The comparative tracking index is used to measure the electrical breakdown (tracking) properties of an insulating material. Tracing is an electrical disturbance that occurs on the surface of an insulating material. During initial exposure to electric arc heat, the material is carbonized. The charred fields are more conductive than pure insulator and increase the current flow. This causes increased heat generation and eventually the insulation becomes completely conductive.

A large voltage difference creates a carbonized trace, gradually creating a conductive leakage path across the surface of the material. To measure the tracking, a certain property and amount of ammonium chloride solution is dropped on the material and the measured voltage expresses the material performance. The better the insulation, the higher the comparative tracking index. For clarity, a higher comparative tracking index value means a lower minimum leakage distance required.

The increasing packing density of components on printed circuit boards leads to increasingly smaller conductor track spacings. For this reason, the comparative monitoring index gains even more importance. This is the resistance tracking index.

Our organization, among numerous test, measurement, analysis and evaluation studies, with its trained and expert staff and advanced technological equipment, within the framework of national and international standards, provides the services of proving solid insulation materials and determining comparative monitoring indexes within the scope of EN/IEC 60112 standard. .