Investigation of the impact of temperature and humidity on the capacitance of dielectric gel used for power electronics

Offshore wind turbines are subjected to harsh environmental conditions which can include high temperatures and elevated levels of ambient humidity. Failure of wind turbines can often be the result of damage over time to the power devices used within converters, leading to significant downtime and maintenance costs. The absorption of moisture within the silicone gel used as a dielectric in power modules poses a potential reliability concern due to its altered electrical properties. Samples of a commercial dielectric gel recommended for use in power modules are subjected to harsh environmental conditions consisting of high temperature alone, high humidity alone, and combined high temperature and humidity. The electrical properties of the gel during these tests are measured using bespoke sensors, and the results of this testing are discussed. A notable increase in the capacitance of samples is observed for the combined high-temperature, high-humidity condition.