The energy revolution is raising the importance of applications such as photovoltaics and e-mobility in which DC voltages of several hundred Volts have to contend with special environmental influences such as condensation and pollution. This is making it necessary to challenge the existing insulation coordination findings. The aim now is to confirm or redefine the safety limits and to develop appropriate protection concepts and tests, ultimately leading to amendment of the relevant standards where required. This is the object of the Federal Ministry for Economic Affairs and Energy (BMWi) funded project "Insulation coordination: Assessment of clearance and creepage distances including ambient aspects in new applications" (IsKoNeu), being carried out by the DKE along with the equipment and system manufacturer Bender GmbH & Co. KG.
Based on the theoretical insights obtained on the structure, influencing factors and testing of insulating materials, a first test series was set up and presented to experts from industry, skilled crafts and trades, associations and standardization organizations on June 30, 2015. The lifespan of the leakage path is influenced not only by the material properties or the coating of the path, but also by numerous environmental conditions such as the electrical and mechanical pressure, the temperature or the humidity. As many combinations of factors as possible and their relevance are to be analyzed using a number of demonstrators and two housing variants. The demonstrators have different conductor path clearances and coatings; DC voltages between 400 V and 1500 V are applied to these. The different housing openings result in different degrees of contamination. Environmental testing based on DIN EN 60068-2-38 is used to simulate continuous load in actual operation; this standard stipulates 240 hour cyclical temperature-humidity tests in a climatic chamber. The insulation is deemed inadequate if it permits the current to flow in unintended paths.
The expertise of the professional public was incorporated in workshops and through the initiation of a dedicated project workgroup. Based on the results of the project, existing safety limits are either to be confirmed or pointers provided for subsequent in-depth investigation. At the same time, concepts and guidelines are to be developed for the creation and revision of normative documents. Once the project is complete these will be fed into the appropriate standardization processes at the international, European or national level to harmonize the limits and protection concepts in national, European and international regulations. Finally, scientific and public awareness publications will be developed. But even if the results of the project "merely" confirm the limits, this would be a good result because it would remove current uncertainties for manufacturers.
Concurrently with the IsKoNeu project, the "DC Low Voltage" Standardization Roadmap was also drafted which, following its planned publication in early 2016, will also address insulation coordination.