Selecting Power Supplies for Industrial Computers

One of the most important factors when specifying an embedded computing system is the power supply.  The application drives the power supply selection process, starting with fully understanding the power requirements and how you want to integrate the power solution, with the availability of COTS standard power modules with proven reliability, the selection of these standard products will perform well if applied within their design limits.  The specific standard products and suppliers must be selected so that the overall power system design will be optimized in terms of cost, reliability and performance.

OUTPUT VOLTAGE (V), CURRENT (A) and POWER RATING (W)

Requirements for supply voltage and current vary widely. When determining the supply-voltage levels required in an application, the current levels will be required for each voltage. Add up the voltage-times-current products: (VxA)=Wattage(Power Rating) for all the supply voltages to determine the power rating.  Then, a power supply model should be selected with a rating that provides at least 25% design margin to ensure safe operation.

When a system has many expansion slots or drive bays always use a higher wattage supply. A higher wattage supply will always run a lightly loaded system well but an undersized supply will fail in an over-loaded system, resulting in potentially costly or dangerous downtime, perhaps even a system requalification with an up-rated supply for mission-critical systems. 

FORM FACTOR AND MOUNTING

Supplies are offered in a variety of package styles with a range of mounting options. The selection of a package style depends on many application considerations like requirements for hot swap redundancy, or the system form factor: rackmount 1U - 5U, ATX, flex ATX, mini ITX, or the venerable mid tower for example.

THERMAL MANAGEMENT

The ambient temperature range expected in the application together with power supply thermal specifications will determine what power supply will be selected.  As a rule, electrical components have upper and lower thermal operational constraints, and the environment in which the system will operate should be considered.

ENVIRONMENTAL FACTORS

For applications where the power supply may be exposed to vibration, contaminants, or high levels of moisture, power supply reliability can be enhanced by the selection of an appropriate supply with properly conformally coated internal components which will help protect against corrosion vibration-induced failures.   

SAFETY STANDARDS

Quality power supplies must meet the UL/EN60950-1 safety standard

Our Engineers are here to help!  If you have questions or concerns about which power supply best meets your application requirements, contact us for a no-obligation consultation, and we will be glad to review your operational constraints and compute requirements to determine the best option for your power supply needs.