WIMA, a maker of film capacitors, employs Wevo potting compounds in its supercapacitor PowerBlock—a cascaded, double-layer capacitor module whose capacitance, rated voltage and dimensions can be individually adapted to a desired application. This allows a range of mobility applications, such as engine starter modules in large construction and agricultural machinery, ships, locomotives, trams and buses, as well as applications in the energy sector, such as slip controls for wind turbines or generators in emergency power systems.
The individual supercap cells of the PowerBlock are fixed symmetrically to the base and at the lid of the housing with the help of Wevo’s WEVOPUR 512 FL potting compound. The polyurethane resin functions as a cell holder, which previously had to be manufactured and adapted to the construction form of the cells separately. In addition, the cells are protected from shocks, oscillations and vibrations due to the tough mechanical properties of the potting compound.
The cells are bonded directly to the metal surfaces of the housing, which allows the thermal surface resistance to be minimized and the thermal conductivity of 0.8 W/mK to be optimally used to dissipate the thermal energy during operation. At the same time, electrical insulation is provided between the cells and the metal housing. With burst power levels up to several thousand watts, electrical safety is ensured by the high tracking resistance, surface resistance and dielectric strength in the PowerBlock. In addition, the potting compound is self-extinguishing in line with UL 94 V-0 and certified according to railway fire protection standard EN 45545-2, reducing the risk of fire and protecting the PowerBlock against thermal runaway.