Enclosed vs Open-Frame Power Supplies: Which Should You Choose?

Enclosed and open-frame are two of the most common formats for AC/DC power supplies, and engineers ask us about the difference all the time. Both convert mains AC to a regulated DC rail; the difference is in the packaging - and that packaging drives cost, cooling, protection and how you mount the unit.

Enclosed power supplies

An enclosed supply lives inside a metal case. That case does real work:

• Protection - shields the electronics from dust, debris and accidental contact.
• EMI containment - the metal housing helps keep conducted and radiated emissions in check.
• Easy mounting - flanges or threaded holes let you bolt the unit straight into a panel or chassis.

The trade-off is a little more weight, size and cost, and the case restricts airflow - so larger enclosed units often add a fan. They are the natural choice for standalone equipment and tougher environments. Typical examples are the Mean Well LRS, RS and NSP families.

Open-frame power supplies

An open-frame supply is the bare PCB with its components exposed, usually on a metal baseplate or with simple standoffs. Without the case it is:

• Lighter and cheaper - less material, lower cost.
• Lower profile - it fits into slim or space-constrained builds.
• Better cooling - components sit in open air, so convection does more of the work.

The catch is that the protection and EMI control now become your responsibility, because the supply is designed to be built inside your own enclosure. That is exactly where open-frame shines: as a sub-assembly within a larger product that already provides the housing.

A quick rule of thumb

If the power supply is a standalone box, or it sits in a dusty, knockabout environment, reach for enclosed. If it is built into your own product that already provides the case and you want to save cost, weight and height, reach for open-frame. Same power, different packaging - and the right choice saves both cost and headaches.

We stock both formats across a wide power range. Browse our AC/DC range, or ask us and we will help you pick the right part.