MTBF

Is an indication of the reliability of a product, not the life expectancy. MTBF (Mean Time Between Failure) is calculated on a "population" of products. It is an indication of the expected time between two failures within this population. Polyamp is logging each reported failure and with the Chi-square method calculate a MTBF value. Our practical MTBF value is ranging around 1 Miljon hours on the PM, PU and PC models. On PSE and PSC the level is slightly lower as they are usually used in warmer applications. The PC1400 & PC2000 use fan cooling and need to be refurbished every 5 years. A common misunderstanding is that a high MTBF indicates long life expectancy. A hard disk memory with 1 million hour MTBF has a very high probability of failure after 3 years continuous operation. Most have experienced that. Most are used to refer MTBF according a standard like MIL-HDBK-217 or IEC61709. Those are used to make a forecast on a product MTBF, before you receive field data. MIL-HDBK-217 has not been updated since 1984, however the principles are still used. The user is then using there own Lambda values on the components used. Very often this forecast give a lower MTBF than the reality, which is probably why the handbook has not been updated. To determine Lambda values SN29500 and the calculation model according to IEC61709, which gives higher MTBF values compared to MIL-HDBK-217. Our experience is that the IEC61709 result is similar to our observed Chi-square values so is a good forecast.

Last Updated on Monday, 04 January 2010 08:38