Open-Frame Power Supply RFQs: Specify Cooling Before Comparing Wattage

A wattage needs an operating condition

When comparing open-frame power supplies, put the cooling condition next to the quoted wattage. A purchasing spreadsheet with only voltage, watts and price can hide differences that matter after the supply is installed inside equipment. Start by asking which rating the supplier is offering and under which installation conditions it applies.

For a published example, XP Power lists different ECS100 ratings for fan cooling, convection cooling and convection cooling with a cover. This illustrates why the enclosure option belongs in a specification. These are specifications of that manufacturer's series, not ratings or approvals of Voltivo Power products.

Send an installation brief with the RFQ

Give each bidder the same drawing revision and a short description of how the equipment will be used. Ask engineering to identify unknown installation conditions before procurement treats a proposal as compliant. A useful brief separates requirements already approved by your team from options you want the supplier to evaluate.

Mechanical reference

Enclosure drawing, board location, mounting orientation, available space, cover option and nearby heat-producing assemblies.

Cooling arrangement

Whether the proposed installation uses natural convection or a fan; provide the planned airflow path and available fan information for review.

Operating conditions

Intended ambient range, input supply range, continuous load and any intermittent load profile, with duration and repetition stated.

Commercial scope

Sample and order quantities, destination countries, documentation requested and which brackets, covers or fans must be included in the quote.

Ask suppliers to mark the applicable rating

Request a model-specific datasheet and a written response identifying the cooling mode, cover variant and applicable derating information. Do not accept a headline power figure as the response to a thermal requirement. Ask the supplier to mark the proposed operating point and explain any conditions still requiring confirmation.

Keep a quotation comparison column for exclusions: a fan, mounting kit or cover assumed by one bidder may be outside another bidder's price. Record these differences before comparing unit costs. If one proposal depends on a cooling arrangement your product team has not accepted, classify it as a proposed design change.

For US and Canadian orders, ask your compliance reviewer which documents and installation conditions must be checked for the exact configuration. Do not turn a component-level catalog statement into a claim about your complete equipment.

Review a sample in the intended installation

XP Power's Essential Guide to Power Supplies, Thermal Management section explains that mounting, surrounding space, load and system cooling affect integration, and calls for checking key component temperatures in the installed assembly against the applicable limits.

Translate that into a procurement acceptance record: identify the supply model and revision, enclosure revision, cooling components, test conditions and the responsible engineering reviewer. Ask that reviewer to define measurement locations and acceptance limits from the relevant manufacturer documents. A purchasing checklist should capture the approved results, not invent a universal temperature limit.

Record unresolved findings separately from the commercial approval. If the sample uses a temporary bench fan or an open enclosure, ask whether the review represents the equipment you intend to manufacture. Have the technical team resolve the difference before treating the sample as an approved production reference.

Keep the approved installation attached to repeat orders

Link the purchase specification to the approved installation and sample record. Agree how proposed changes to the supply, cover, fan or mounting arrangement will be reported and reviewed. For distributors, retain this information with the equipment configuration rather than treating all units sharing the same voltage and wattage as interchangeable.

To start an open-frame power supply inquiry with Voltivo Power, share the load requirements, enclosure drawing, intended cooling arrangement, destination market and quantity. Ask us to review the proposed configuration. Model-specific ratings, documentation, customization scope, sample availability and commercial terms are confirmed during that review.