Do not keep a spare VFD in your storage for long period of time. It is very likely would be unusable, regardless the type and manufacturer. Why? Because of the capacitor degradation. Worst thing you can do is take such a VFD from the warehouse and plug it into power and load. There is a procedure of revitalisation that helps sometimes but no garantie at all to be succesful ( it is available for free only to our costumers). You can't find such a warning in most manual instructions. Unfortunately. The figure below is a VFD of 1,5 kW that successfully passed the procedure after 10 years of storage.
