High-voltage tests under humid heat – Challenges & solutions
Because as soon as moisture and temperature fluctuations come into play, things get really tricky.
Components in high-voltage systems generate a lot of heat themselves, which leads to a microclimate that can distort test results.
So how can we ensure that the tests really reflect the real operating conditions?
Let’s take a closer look.
What are humidity-heat tests?
They simulate high humidity and temperature changes, which electronic components are exposed to in reality.
🚗 Example from practice:
An electric vehicle that stands in the hot sun during the day and cools down significantly at night.
In humid regions, condensation can form, which burdens the electronics.
Why is this a special challenge for high-voltage technology?
High-voltage components are subjected to extreme electrical stress.
Additional risks due to moisture and temperature fluctuations:
⚡ Insulation weakness:
Moisture can attack insulation materials → Danger of partial discharges or breakdowns
⚡ Corrosion & leakage currents:
Moisture on circuit boards or connectors can lead to short circuits or material fatigue
⚡ Material aging:
High temperatures + moisture accelerate the aging process of seals, plastics, and adhesives
📌 Example:
An inverter in an electric vehicle generates heat itself due to high current flow.
This heating can cause a different climate on its surface than in the climate chamber.
That means: Without adapted test methods, failure patterns could be overlooked!
The problem with the microclimate
- Directly on the component surface, it is often warmer than in the climate chamber
- This can result in lower relative humidity there
- Moisture does not settle as expected → Failure patterns like condensation could remain undiscovered
🚨 Danger:
A component could seemingly have no issues with moisture during the test – but in real operation, it could be vulnerable to condensation!
That’s why we need to ensure that our tests take these effects into account.
Typical failure patterns in high-voltage systems
🔸 Partial discharges & corona effects
- Occur under high electric fields
- Can destroy insulation materials in the long run
- Measurable with special partial discharge measuring devices
🔸 Flash Over (Breakdown)
- Breakdown over the surface of an insulator
- Particularly critical in moisture or contamination
- Comparable to a lightning strike finding its way over a damp surface
🔸 Material fatigue & leakage currents
- Moisture can bridge creepage distances and cause short circuits
- Thermal stress can lead to crack formation
- Plastics, adhesives, or coatings can become brittle and crack
How do we improve the tests?
To obtain reliable and realistic results, tests must be well planned.
1️⃣ Simulate realistic operating cycles
- Not only continuous load, but also phases with low load should be tested.
📌 Why?
- Many failures only occur during cooling or in idle state!
2️⃣ Consciously induce worst-case scenarios
👉 E.g., deliberately provoke condensation phases
📌 Why?
- To check whether the component can handle sudden moisture uptake.
3️⃣ Control the microclimate
- Active temperature regulation of the components
- Cooling the test chamber to avoid local overheating
- Ensure that the relative humidity at the component really matches the environment
4️⃣ Optimize measurement and monitoring methods
🔍 Measure surface temperature → Use infrared cameras or thermocouples
🔍 Continuously monitor partial discharges
🔍 Regular insulation measurements during climate testing
📌 Why?
- This allows us to identify and optimize weaknesses early.
5️⃣ Define clear test specifications
- How long is the component powered?
- What temperature and humidity fluctuations are realistic?
- Should condensation be deliberately generated?
Only if we know exactly what we want to test will we get meaningful results.
Conclusion: Why is the effort worth it?
High-voltage systems are safety-critical components in modern vehicles.
🔹 Humidity-heat tests uncover weaknesses before failures occur in the field
🔹 Microclimate effects must be taken into account to obtain realistic test results
🔹 Optimized test methods help to improve the lifespan and reliability of high-voltage components
At enveon, we conduct high-voltage tests with state-of-the-art technology and detailed analysis.
Because one thing is clear:
If high-voltage components fail, it can have serious consequences.
That’s why we test as realistically as possible – so our customers can be on the safe side. ⚡
