High Voltage, Higher Standards: Using Industrial CT to Detect Delamination in Power Modules

Keeping the power grid up and running can depend on several moving parts. Modules, sensors, reclosers, and switchgear are common elements of the high-voltage system. They must be able to handle increasingly harsh and unpredictable conditions. Heavily populated areas, increased electric vehicle charging, aging infrastructure, and severe weather exacerbated by global warming are impacting the risk of failures and outages. Internal delamination or hidden defects in high-voltage components can compromise integrity without obvious signs. This can result in partial discharge, arcing, or complete failure. Nel PreTech Corporation (NPC) is a trusted partner for industrial CT scanning, non-destructive testing (NDT), and failure analysis. Teaming up with our CT experts gets engineers non-destructive insight into the internal structure of high-voltage components. Our team can provide solid answers when time and money are at stake. 

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1. Power Modules Under Pressure

Power modules in the high-voltage energy sector encompass semiconductor technology and a collection of internal circuit components. The core function is to convert power and manage energy flow with minimal loss. 

Power modules in this sector can include:

• Solid dielectric switchgear
• Overhead reclosers
• Underground terminations and cable accessories
• Voltage and current sensors
• Transformer bushings and encapsulated junctions

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Most defects from mechanical stresses, manufacturing processes, or environmental conditions can’t be detected visually or with electrical tests. Delamination within encapsulants or potting materials is particularly difficult to identify without alternative methods. Industrial CT scanning can reveal voids in the epoxy potting around a high-voltage termination, internal bond failures, warpage, or the presence of contaminants. 

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2. Understanding Delamination in High-Voltage Systems

Delamination is the failure of the bond between insulation layers or a dielectric and its encapsulant. This can create air or gas pockets, leading to small energy discharges. Over time, these micro-discharges can break down the insulation, reduce dielectric strength, and lead to complete failure. 

Delamination can occur from:

• Manufacturing processes: incomplete curing
• Contaminants or trapped air
• Expansion or contraction of two joined materials at different rates (mismatched CTE)

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3. The Power of Industrial CT Scanning for Failure Prevention

To visualize internal bond failures or voids in encapsulated assemblies, you need a system capable of penetrating dense metal and composite structures. Industrial CT scanning is the ideal non-destructive method for detailed imaging of these interfaces. Nel PreTech Corporation runs top-tier, high-energy CT systems, including the Zeiss Metrotom 800 and 1500, built to reconstruct 3D images of internal and external geometries. CT data is processed using advanced reconstruction software to quantify and measure delamination. In addition to visualization, dimensional analysis tools are used for further measurement and alignment checks.

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4. Common CT Applications in Power Distribution Equipment

NPC’s CT analysis capabilities provide valuable insight into:

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1. Prototype validation: Detecting hidden process defects during R&D of high-voltage modules.
   
   
2. Production quality checks: Ensuring insulation and bonding consistency.
   
   
3. Failure investigation: Root-cause analysis after electrical or mechanical failure.
   
   
4. Supplier verification: Auditing components from multiple vendors for internal consistency.
   
   
5. Material and process development: Comparing power module system components to CAD or part-to-part for long-term stability.

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5. From Data to Action

Beyond imaging, Nel PreTech provides 3D defect quantification and statistical data:

• Defect locations
• Delamination thickness and material density variation
• Quantitative correlation to performance metrics

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After CT scanning a high-voltage assembly with an aluminum grounding mesh at 25 microns, NPC was able to detect hidden voids, delamination, density variations in the epoxy, and foreign material inclusions. The manufacturer equated this to their process and made the necessary changes to resolve the defects. Our data helps engineers refine mold design, curing parameters, and assembly sequences. Engaging in a proactive collaboration with Nel PreTech can prevent costly recalls or field failures before the first shipment leaves the factory.

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6. Challenges and Best Practices in CT Analysis for High-Voltage Components

Challenges:

• Scanning large or dense power modules
• Differentiating between materials with similar densities
• Balancing field-of-view with resolution

Best Practices:

• Using reference parts for comparison
• Correlating CT data with electrical test results
• Optimize beam energy and filtration to scan high- and low-density materials

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7. Reliability Starts with Visibility

Even the most advanced and modern high-voltage insulation systems can become victims of delamination. With advanced CT scanning from Nel PreTech, manufacturers and engineers gain the structural data needed to ensure dielectric reliability. 

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If you need accurate visualization to make informed evaluations, contact Nel PreTech or request a free quote.

Seeing is better than believing.

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