For most Westermo products we use MIL-HDBK-217 and Telcordia SR 332. There is no preferred version, which is why we test to both.

What do the results mean?

To ensure credibility, Westermo, along wit other leading vendors, has its devices externally tested and verified by independent third parties. This means the MTBF results we share are both accurate and trustworthy, giving customers confidence that our products are fully prepared for deployment in the field.

Take the Lynx 3000 (link) series as an example. This product is available in several models, with either Power over Ethernet (PoE) or non-PoE models.

Three important take-aways for these results:

1. MTBF is always given in hours. To put it in perspective, 1,138,000 hours equals roughly 129 years. Of course, this doesn’t mean the device will literally last for more than a century - it simply means that, statistically, failures are extremely unlikely over the product’s expected lifetime.

2. The second thing to note is that the MTBF varies per product. Different models include different components, so results will naturally vary. It’s important to look at the MTBF value for the specific device you plan to purchase rather than relying on the highest figure. Still, even the lowest result here represents well over half a century, which reflects exceptional reliability.

3. The last thing to note is the variation between standards. As discussed earlier, MIL-HDBK-217 is stricter and more conservative, while Telcordia SR-332 tends to produce more generous results. When comparing vendors, always check which standard has been used - some manufacturers may report higher MTBF values simply because they rely on less conservative testing.

At Westermo, we often highlight results from MIL-HDBK-217 because of its stricter methodology. This ensures our products are measured against the toughest standards, reflecting their suitability for harsh, demanding, and mission-critical environments. Telcordia SR-332 is also used, particularly for benchmarking against other vendors in the telecommunications industry.

Conclusion

In summary, MTBF is a valuable calculation that predicts the average time between failures in a repairable system. While it serves as an important benchmark when selecting or comparing devices, it should never be the only factor considered.

Other measurements, such as MTTR are equally important, as it’s evaluating the supplier behind the product. Reliability is not just about numbers on paper - it’s about how the product is manufactured, whether its components are ethically sourced, and whether there is full traceability and rigorous testing throughout the supply chain.

At Westermo, we take all these factors into account, ensuring that our products are not only backed by strong MTBF results - but are also designed to meet the highest possible standards for long-term, reliable performance.