Quick answer: use a power supply thermal test to verify a defined machine configuration, not to decorate a simulation with a “pass” label. A model predicts the consequences of chosen assumptions; a chamber creates a controlled test environment. Neither a case-temperature snapshot nor a maximum ambient figure establishes that every installation can deliver the full nameplate current.
Start with the question the engineering team must answer
For an OEM, the useful question is usually specific: can this revised enclosure, with its actual duty cycle and neighboring heat sources, operate within the supplier’s accepted limits? Decide that question before purchasing chamber time or building a detailed model. A test intended to qualify a cabinet layout is different from incoming inspection of the supply, and different again from a component-level reliability investigation.
Keep three records separate: the supplier’s rated configuration, the engineering prediction and the measured equipment result. This article proposes a handoff method; it does not report a completed WEHO chamber test or certify a customer machine. Qualified personnel should define isolation, protection and safe access before any energized test.
Why this enclosed-supply example needs its own boundary
The examined WEHO LRS-150-12 sample is marked 12V and 12.5A. Its approved mechanical drawing gives a 159mm long roof axis, a 97mm terminal-edge span and a 30mm base-to-roof height. The authentic photographs show a shallow perforated metal chassis, seven guarded terminals and no fan. Those facts identify the sample; they do not provide the missing enclosure-specific thermal result.
The current WEHO LRS-150 product page describes natural-air cooling, but its input descriptions are not internally uniform. The received label, approved sheet and public input wording must remain separately attributed. Request the applicable revision before qualification rather than combining their broadest values. Likewise, a stated working-temperature interval is not an unconditional full-load guarantee at its upper endpoint.
Simulation is a design comparison, not a release receipt
A thermal model is most useful before the equipment is fixed: compare placements, exposed surfaces and airflow arrangements using a consistent set of assumptions. Texas Instruments’ thermal-analysis note distinguishes analytical, simulation and hands-on approaches, and describes how modeling can reveal heat distribution and hotspots. That guidance concerns power-device analysis; it is not a validated digital model of this WEHO supply.
For an enclosed purchased supply, do not create fictional internal semiconductor losses or thermal resistances because a simulation package requires them. Ask for supplier-supported data, use measured external power loss where appropriate and label any simplifying representation. Treat uncertain heat generation, airflow and contact assumptions as items to investigate, not hidden constants. A colorful result can still be wrong if the enclosure boundary is wrong.
Make the comparison reversible
Save the original and revised layout with the same load case and the same uncertainty labels. If moving the supply appears beneficial, state which assumption caused the change. Do not report a predicted temperature as a measurement, and do not let an assumed internal hotspot become a product specification in the purchasing document.
Chamber testing must preserve the machine configuration
Before a test, agree which configuration is represented: mounting orientation, base material, cover state, surrounding components, cable routing and the equipment duty cycle. Record the actual input and output conditions instead of borrowing them from another model or voltage variant. Place environmental and case observations in different fields so the chamber controller’s setpoint is not mistaken for the air beside the supply or for an internal component temperature.
Use a documented, safe measurement method and accessible locations. Do not insert a sensor through a ventilation opening, remove guards or open the power supply merely to obtain an attractive photograph. Instrument uncertainty, timing and the reason for selecting a location belong in the report. Agree how stabilization and acceptance will be evaluated before collecting data; this guide invents no universal duration or temperature threshold.
Compare like with like before changing the design
| Comparison field | Prediction record | Test record |
|---|---|---|
| Equipment version | Named layout and modeled enclosure boundary | Actual enclosure, covers, mounting and adjacent components |
| Electrical condition | Declared load profile and supported loss assumption | Recorded input, output and operating sequence |
| Temperature location | Clearly defined model location | Accessible measured location and instrument uncertainty |
| Decision | Candidate design improvement, not acceptance | Result assessed against agreed supplier/equipment limits |
When prediction and measurement differ, first check whether they describe the same boundary. A changed cover, different base contact or an unrelated load cycle can invalidate the comparison. Retain the discrepancy and its resolution. Re-run the relevant case after a meaningful design change rather than silently replacing the original result with a more favorable screenshot.
What procurement should receive
The proposed release packet contains the exact model and revision, an identified equipment configuration, the prediction assumptions, the measured record, unresolved discrepancies and the named engineering acceptance decision. A “thermal test passed” sentence without that context is insufficient for a changed machine. Preserve the distinction between supply capability and equipment verification when the project moves from design to purchasing.
Frequently asked questions
Can simulation replace chamber testing?
It can help compare designs. Whether it is sufficient evidence depends on the agreed qualification objective and validated assumptions; this article supplies neither a universal exemption nor an accepted model.
Does a 12.5A label prove full output at every ambient temperature?
No. Confirm the applicable derating, installation and input conditions with the supplier for the exact revision.
Should a hotter case automatically fail?
No generic limit is supplied here. Evaluate the defined locations against the applicable acceptance criteria and investigate configuration changes.
Can I add a fan to obtain a better result?
Only as a documented equipment change, with a revised boundary and subsequent verification. Do not depict an invented fan inside this source fanless supply.
What changes require another review?
Examples include enclosure, mounting, airflow, adjacent heat sources, load sequence or supply revision. The responsible engineer defines the affected requalification scope.
Need an order-specific thermal basis? Send WEHO the exact model, input conditions, load profile and proposed mounting arrangement, and request the applicable limits and revision before release.
