该标准还适用于没有安全等级的组件，因此未获得一定性能水平的认证。这可能是一个简单的继电器或接触器，无论最终都进入与安全有关的系统中。因此，对于此类组件的制造商来说，能够提供MTTFD值越来越重要。
MTTFd can be determined directly for electrical or electronic components by doing either a parts count or a Failure Mode and Effects Analysis (FMEA). For electro-mechanical, hydraulic, and pneumatic components that have a cycling operational profile, it is more difficult to provide an MTTFd value because the value depends on how often the device is used over time (i.e., how often for example a switch is activated). For these devices, a B10d value is needed. B10d is the number of operating cycles after which 10 percent of a population of a component will have failed dangerously. With the B10d, the MTTFd can then be calculated.
我们可以提供帮助
UL可以assist you in obtaining an MTTFd for any type of component. We can do the MTTFd determination via parts count or FMEA. The latter is more accurate and may provide more optimistic values, but is more labor intensive. We also offer B10d testing for MTTFd determination. This is done through destructive lifetime testing, the methods for which are provided by the following standards:
不要求第三方参与提供MTTFD值（制造商可以自我策划），但提供此功能所需的资源可能会证明是有问题的，在制造商的核心竞争力之外。此外，通过使用第三方验证MTTFD索赔的可信度提供了价值。
有关UL的MTTFD计算和B10D测试服务的更多信息，请联系：
凯文·康纳利（Kevin Connelly）
631-546-2691
kevin.connelly@us.ul.com
