This document standardizes the requirements for power conversion devices (PCDs) for the computer and telecommunications industries. The phrase “power conversion devices” refers to ac to dc and dc to dc modules, converters and power supplies. This specification sets the requirements for design; qualification testing; conformance testing and manufacturing quality/reliability processes, but does not include the functional requirements of the specific equipment. PCDs addressed in this document are used in the electronics industry to provide conversion of main power sources, usually ac to lower dc voltages for direct use of electronic circuits or as a secondary source for additional dc to dc PCDs to provide several dc voltage levels for various electronic devices in a product. Revision B of this document includes updated performance evaluations, including thermal and vibration; temperature, humidity and bias; temperature cycling; shock and vibration; random vibration and free-fall drop and shock tests. Additionally, nearly all of the device (component) derating guidelines were updated, including capacitors, resistors, diodes, transistors, transformers, inductors, microcircuits, circuit breakers, fuses, relays, switches and oscillators. The revision also provides more current and correct definitions for reliability terms, including the mean time between failure or MTBF.