Background: OEM Power Modules and the Target System

In this project, an OEM supplier provided a family of compact OEM power modules to a customer building industrial equipment. The modules converted AC and DC inputs into multiple isolated DC rails and were intended to be mounted on a backplane together with control and I/O boards. The OEM had already performed basic EMC testing in a reference setup and provided application notes about grounding and filtering.

The end customer, however, used the modules in several different products. Mechanical layouts, cable routing and loads changed from one system to another. They had previously seen that apparently “EMC-compliant” modules could still cause issues once installed in real cabinets. To avoid late surprises, both teams agreed to run emc testing for oem electronics that reflected the real environment.

TPS was asked to host and coordinate this pre-compliance project, acting as a neutral lab where the OEM and integrator could test the modules together and identify integration rules that would work across multiple product variants.

EMC Challenge: From Datasheet Compliance to Real Integration

During the first joint review, it became clear that the integration context was much more complex than the OEM’s reference design:

• Modules were mounted on different types of backplanes and metalwork, affecting stray capacitances and grounding paths.
• Some products had long I/O and power cables leaving the cabinet, changing both emissions and immunity profiles.
• Loads ranged from sensitive analogue measurement circuits to noisy digital boards and motor drivers, all sharing the same DC power distribution.

The OEM’s existing EMC reports were valuable, but they did not answer the question the customer really cared about: how would the OEM power modules behave as part of the complete system, and which integration choices made the difference between a robust design and a fragile one?

TPS EMC Test Plan for OEM Electronics

TPS proposed an EMC test plan that focused on the integration level while still allowing the OEM to relate results back to their module designs:

• Representative system build. We assembled a test system with one or more OEM modules, typical control and I/O boards and wiring representative of the industrial product. When necessary, detachable sub-assemblies allowed us to isolate individual modules.
• Key EMC tests. We concentrated on conducted and radiated emissions from the power electronics, along with EFT, surge and RF immunity tests on supply and interface lines. Tests followed the same standards used at the certification house, but with more freedom to experiment.
• Shared observation. Engineers from both OEM and integrator teams were present in the lab, so that everyone saw the same behaviour and could discuss options in real time.

This approach turned the EMC lab into a collaborative workspace where both sides could refine guidelines for integrating the OEM modules into different systems.

Debug and Design Agreements

With the system built and the EMC plan in place, the teams stepped through emissions and immunity tests together. For each observed issue, they checked whether the root cause lay in the module design, the integration choices or a combination of both.

• Emissions control. Where narrow-band peaks appeared, the OEM and integrator tuned filters and adjusted wiring to reduce coupling. Some changes became module-level options; others became integration rules for cable routing and grounding.
• Immunity robustness. During EFT and surge tests, they monitored voltage rails, error flags and communication status. In a few cases, minor firmware updates and reset strategies on the system side were enough to move from borderline to robust behaviour.
• Documented integration rules. Each verified improvement was written down as a simple rule: for example, preferred mounting locations, recommended shield terminations and minimum distances between noisy and sensitive circuits.

This joint debug process meant that oem electronics and the customer’s system design evolved together, instead of pushing responsibility to one side only.

Results: a Qualified Module Family and a Shared EMC Flow

After several days of focused work, the teams agreed on a stable configuration and design rules. When the final system was tested at a third-party lab, it:

• Met conducted and radiated emission limits with consistent margins across product variants.
• Maintained correct operation during immunity tests, with no unexpected resets or data corruption.
• Showed similar EMC behaviour across cabinets, thanks to the harmonised integration rules.

Perhaps the most important outcome was process-related: the OEM and integrator now had a shared, repeatable way to qualify new OEM power modules using EMC pre-compliance testing before formal certification.

How to Prepare OEM Modules and Systems for EMC Testing

If you work with OEM electronics—either as a supplier or as an integrator—you can prepare for EMC testing with TPS by collecting a few key items:

• Block diagrams of the OEM modules and the target system, including power and communication paths.
• Information about mounting, grounding and wiring: backplanes, cable types and lengths, shield connections.
• Existing EMC reports and application notes from the OEM, plus any field issues seen in similar products.
• A shortlist of operating modes and configurations that matter most for your end customers.

With this information, TPS can organise emc testing for power electronics at the integration level, run pre-compliance tests in our lab and help both OEM and integrator walk into third-party certification with far fewer unknowns.

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Key questions this case answers

This case study addresses the core search questions behind EMC testing for OEM power modules and electronics:

• Why OEM modules that are “compliant on paper” still need EMC testing in the real system.
• How to structure EMC pre-compliance for OEM electronics so that both supplier and integrator learn from the results.
• Which design and integration changes most effectively improve EMC margins for OEM power modules.
• How to turn one successful project into a repeatable EMC flow for future OEM designs.