Risk Assessment for Insulation Coordination in High-Voltage Electronics
Manufacturer-independent assessment of contamination, humidity, materials, and coatings to support reliable decisions on insulation coordination.
Insulation Safety Why Insulation Coordination in High-Voltage Applications Goes Beyond Clearance and Creepage Distances
As operating voltages increase, the dimensioning of clearance and creepage distances and the electrical properties of the insulating materials used become increasingly critical. However, the reliability of a high-voltage system cannot be determined by design geometry alone.
Particulate contamination, ionic residues, moisture exposure and the effective protective performance of coatings can significantly influence the insulation behaviour of electronic assemblies and power modules under electrical stress.
A robust insulation coordination assessment must therefore consider the actual environmental and operating conditions throughout the application lifecycle. This includes verifying whether the pollution degree assumed during design is representative of the real conditions encountered in service and whether the resulting insulation concept provides sufficient margin under those conditions.
How to determine the appropriate pollution degree for electronic assemblies
Risk FactorsWhich Factors Determine the Actual Insulation Risk?
Whether a high-voltage electronic assembly provides sufficient insulation robustness under its intended operating conditions cannot be assessed based on a single cleanliness value or an individual material property. The actual insulation risk results from the interaction of multiple influencing factors.
Particulate Contamination and Technical Cleanliness
Particles can become critical if they bridge electrical clearances or become conductive under the prevailing environmental conditions. Their assessment therefore needs to consider not only particle count and size, but also material, shape, location, mobility and the applied electrical stress.
Ionic Contamination
Ionic residues can originate from materials, manufacturing processes, fluxes, cleaning processes or handling. In combination with moisture and electrical bias, they can promote unintended surface conductivity, leakage currents, corrosion and electrochemical migration.
Moisture and Condensation
Moisture can activate existing contaminants and thereby alter the electrical behaviour of a surface. It is therefore important to consider not only the ambient relative humidity, but also whether local condensation or dew formation can occur.
Coatings and Insulating Materials
Conformal coatings, encapsulation materials and other electrical insulation materials can make a significant contribution to insulation reliability. However, their protective performance depends on the material properties, application quality and ageing behaviour, as well as on potential defects such as voids, cracks, bubbles or delamination.
The presence of a coating alone should therefore not be considered sufficient evidence of effective insulation protection.
Project PhaseWhen Does Insulation Coordination Become a Critical Project Issue?
A more detailed assessment becomes particularly important when assumptions made for an existing insulation concept can no longer be applied with confidence to a new application.
Typical situations include:
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moving to higher operating voltages or a new high-voltage platform,
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when clearances, creepage distances or the selected pollution degree need to be justified to customers or OEMs,
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changes to materials, protective coatings or manufacturing processes,
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uncertainty about which levels of particulate or ionic contamination are acceptable for the application,
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abnormalities observed during humidity or climatic testing,
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leakage currents, tracking or sporadic insulation failures,
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existing specifications that do not adequately reflect the actual electrical and environmental stresses experienced by the assembly.
At this point, the key question is no longer simply whether the assembly is clean, but:
Which contaminants or material properties could become critical under the actual electrical and environmental conditions of the application?
Unsure Whether Your Insulation Concept Is Robust Enough?
Our experts help identify the relevant risk factors and determine which analyses or tests are needed for a reliable technical assessment.
Analytical AssessmentHow Can Insulation Risks Be Assessed Reliably?
The appropriate analytical approach depends on the specific technical issue being investigated. Different methods provide insight into different failure mechanisms and risk factors.
A reliable assessment therefore starts with identifying the relevant risk drivers and selecting the analytical methods or test procedures that best address the specific application and failure scenario.
Technical Cleanliness
Assessing Particles: In addition to characterizing particle size, shape and material, particulate contamination can also be assessed to determine under which conditions a particle may become electrically critical.
Frit voltage analysis, for example, can be used to evaluate the conductive behaviour of particles under defined electrical stress.
Ionic Contamination
Differentiating Ionic Contaminants: Ion chromatography enables individual ionic species to be identified and quantified. This makes it possible to determine which contaminants are present and to investigate potential links to specific materials or manufacturing processes.
Conformal Coating
Assessing Insulating Materials and Coatings: For conformal coatings, molding compounds and encapsulation materials, it is important to determine whether their protective performance is maintained under the relevant operating and stress conditions.
Depending on the assembly design and the specific technical question, environmental testing, electrical testing or, in the case of encapsulated power modules, electrical impedance spectroscopy can provide additional insight into the condition and integrity of the insulation system.
Assessing Results in the Context of the Application
A single measurement result does not, by itself, define the risk of failure.
Its relevance can only be assessed in combination with the operating voltage, geometry, material system, environmental conditions and mission profile of the specific application.
ApproachFrom Risk Assessment to Reliable Findings
To turn the risk assessment into a reliable basis for insulation coordination decisions, ZESTRON follows a structured three-step approach. The scope of the assessment and the analytical methods used are tailored to the specific technical question and the evidence required.
Step 1
Assess the Application and Operating Conditions
The assessment begins by reviewing the voltage level, electronic assembly design, operating environment, known failure modes, technical requirements, and specifications. This establishes which factors are actually relevant to the specific insulation coordination challenge.
Step 2
Assess the Relevant Risk Drivers
Based on the specific technical question, the relevant influencing factors are investigated in a targeted manner. Depending on the application, these may include technical cleanliness, ionic contamination, humidity exposure, and the protective performance of coatings. Analytical methods and validation are selected to provide reliable evidence for the specific risk assessment.
Step 3
Assess the Risk and Define Appropriate Measures
The results are evaluated in the context of the application, environmental conditions, and relevant requirements. This provides a transparent risk classification, prioritized measures, and recommendations for further validation or technical risk mitigation.
Technical SupportWhen Is an Application-Specific Risk Assessment Recommended?
An application-specific assessment is particularly valuable when applicable standards or standard test methods alone do not provide sufficient insight into the actual insulation risk.
This may be the case when:
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the selected pollution degree needs to be technically justified,
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particulate or ionic contamination needs to be assessed in terms of its actual criticality,
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issues arise under humidity or high-voltage conditions,
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the protective performance of a coating or insulating material is uncertain,
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new materials, processes or voltage levels are introduced,
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robust data is required for release decisions, internal reviews or technical discussions with customers.
ZESTRON combines analytical testing with an application-specific assessment of the relevant operating conditions and risk factors. The objective is not to generate another measurement value, but to provide a technically sound assessment of the relevant risks and the next steps that should be taken.
Independent Risk AssessmentGet a Reliable Assessment of Your Insulation Risks
When insulation coordination becomes a project issue due to OEM requirements, current failures, or a transition to higher voltage levels, an initial consultation can quickly clarify the objective, boundary conditions, and the most effective path to reliable findings.
As an independent service provider, ZESTRON assesses the specific technical question on a manufacturer-neutral basis. Alternatively, a sample assessment can provide a structured starting point.
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Confidential and structured. With NDA on request.
Whitepaper CollectionAnalytical Approach to Implementing Insulation Coordination
At 400 V to 1200 V, extrapolated low voltage assumptions are no longer sufficient. This white paper explains how pollution degree, contamination, and insulating materials can be assessed using an analytical approach.