These capacitors were removed from a failed VFD. The cooling fans had failed and the unit was running very hot. These capacitors failed violently, as you can see from the photos. This repair was compounded by the fact that the capacitors were sandwiched between two buss bars and were a very special physical size. This made the replacements difficult to locate within any reasonable amount of time. Substitutions were impossible due to the size requirements. This unit was critical to the plants production and the cabinet dimensions made a complete VFD replacement a lengthy project as well. The decision was made to repair the unit if at all possible. While waiting for the exact replacements, Delta technicians devised a method for substituting the capacitors using several other capacitors of the proper value and voltage, but a much larger physical size. These units were linked to the buss via a tethered set of cables, which placed the temporary capacitors OUTSIDE of the VFD! This allowed the VFD to function in its application until the exact capacitors were received and installed.
This failure may have been avoided by an inspection and a preventive maintenance visit. This would have identified the failed fans which would have kept the VFD temperature from rising, causing the premature failure of these capacitors. Ask about Deltas P.M plan for your VFDs!