Environmental Challenges of Power Supplies, Part 3

Temperatures, moisture, condensing atmospheres, radiation… these are some of the foremost environmental hazards that manufacturers must plan for when designing military power supplies, but there are even more potential environmental challenges that must be considered. One more consideration that power supply manufacturers must be able to design solutions for, and it’s a big one: the shock and vibration factor.

As anyone who has experience powering systems on air and sea platforms knows, these systems can be subject to enormous amounts and types of shock and vibration. Consequently, military power supplies on such platforms must stand up to significant shock and vibration from a broad range of sources: maneuvering, acceleration, weather conditions, sudden impact, etc.

Specifically, all products designed for use in U.S. naval applications are required to meet the shock requirements of U.S. Military Specification 901 (MIL-S-901) which can range up to 90g (a shock rating equivalent to 90 times the normal force of gravity). Vibration testing of electronic equipment like power supplies is governed by U.S. Military Standard 810 (MIL-STD-810), with individual regimens selected for each product in accordance with its end use. Remember, commercial power supplies are not normally designed to accommodate the levels of shock and vibration anticipated by these specifications and standards. That is a major distinction between commercial and military power supplies: reliability in any environment.

Although most modern power supplies are very reliable, consideration of shock and vibration is critical when comparing commercial power supplies to military-grade supplies. Often, commercial supplies are manufactrured to comply with new regulations that decrease their capability to withstand shock, vibration, and other environmental stresses. An example of one of these regulatory standards is the European Union’s Restriction of Hazardous Substances Directive, which restricts the use of certain materials and recommends the use of others that are less resistant to shock, vibration, and emissions.

Shock and vibration are environmental conditions that can produce sudden catastrophic failure of power supplies, so they are never to be taken lightly when selecting supplies for mission critical applications. The exact wrong time to find out that your power supply cannot withstand shock and vibration is when it fails as you are maneuvering violently to escape a hazardous situation.