Radial shaft seal: hardening due to high thermal load (Bild: Magna Powertrain)

24.10.2023 Validation cycles for electrical systems from a Seal’s perspective

Discussion of LV124 compared to established seal test sequences

von Dr.-Ing. Jan Gölz (Magna International)

Seals in electrical systems in automotive applications face various challenges. One significant challenge are validation cycles for electrical systems or components. Compared to established approaches on sealing system validation, some test cycles are much more severe regarding thermal loads. This can lead to sealing system failures in the respective test run, provoked by non-representative failure modes. To avoid incorrect conclusions on the sealing systems’ performance, it is mandatory to review the test parameters critically. To review the thermal loads within this paper, test cycles from the standards LV 124 for electrical components, DIN 3761 for radial shaft seals and ISO 1817 for oil compatibility testing are compared.

One significant challenge for sealing systems are validation cycles for electrical systems or components. Here the LV 124 standard for electrical or electronic components is used as an example. LV 124 is not focused on sealing systems, but on electrical components in general, and some of its test cycles are more severe than established sealing system test cycles. Especially for oil-elastomer sealing contacts, this can lead to failures of the sealing system by failure modes that do not correspond to the field.

The article gives an overview of the sealing systems in scope, chemical and thermal degradation of elastomers and Arrhenius’ approach on aging behaviour. Afterwards, the relevant test cycles in LV 124, DIN 3761 and ISO 1817 are introduced, test parameters defined and compared regarding thermal load. The latter two are
established validation cycles for sealing systems with elastomeric seals. Equivalent test temperatures and test durations are calculated and the resulting thermal loads are compared. Afterwards some examples of sealing system failure modes in LV 124 cycles are shown and discussed.