Industry: Laboratory  
Application: Analytical Equipment
Power Solution: UHP-200 series
 
The MEAN WELL UHP-200 series is a slim-profile, fanless 200W AC-DC power supply designed for high-density industrial and automation systems. With high efficiency (up to 94%) and international safety compliance, including UL/IEC 62368-1, IEC60335-1, IEC61558-2-16, and much more internationally. The UHP-200 is widely used in industrial control, instrumentation, and electrical equipment. It meets stringent EMC emission and immunity standards including EN 55032 Class B, EN 55014, EN55035, and EN 61000-3-2/-3, making it suitable for noise-sensitive environments.
 
However, despite its robust EMI design, electromagnetic compatibility in the end system still depends heavily on system-level integration, including cable routing, grounding, enclosure shielding, and input filtering.
 

 
CUSTOMER PAIN POINTS:
 
A customer integrated the UHP-200-24 into a variety of end applications, each with unique mechanical and electrical environments. As part of their internal quality policy, the customer applies stricter self-imposed EMC margins beyond the standard regulatory limits to ensure consistent performance across all deployment scenarios. In one particular application, the UHP-200-24 did not meet these tighter internal thresholds, with conducted emissions exceeding their predefined margin on 150 kHz, which is within the low-frequency range typically affected by switching noise and common-mode interference. This prompted a joint investigation with MEAN WELL to identify the root cause and evaluate potential optimizations, particularly exploring options such as optimizing the input filter or adjusting the switching frequency of the supply.
 
 
ENGINEERING SOLUTION:
 
MEAN WELL’s engineering team immediately collaborated with the customer to analyze the setup. The metal case, long AC cable, and grounding method were evaluated for potential EMI coupling paths. After system review, it was determined that additional common-mode attenuation was required. The EMI peak near 150 kHz was attributed to the low-frequency switching harmonics and insufficient common-mode suppression in the specific customer installation.
 
To solve this, two input Y-capacitors in the EMI filter circuit were replaced with higher capacitance values to enhance common-mode noise attenuation, while still keeping leakage current below the 0.75mA safety threshold.
 
CONCLUSION:
 
The UHP-200 series is a highly reliable, compact power supply that meets stringent international safety and EMC standards. However, EMC performance in real-world installations can be affected by system-level factors. In this case, MEAN WELL’s collaborative approach with the client allowed rapid identification and resolution of the EMI issue by enhancing the internal Y-cap filtering.