LFD is best suited for medium and large power transformers, typically from 5-10 MVA and above, where the mass of cellulose insulation is high and conventional external heating becomes inefficient. It is especially effective for HV and EHV units with thick windings, disc insulation, and long moisture diffusion paths. For small distribution transformers, the complexity and setup effort of LFD is usually not justified, while for large grid transformers it is often one of the most efficient deep-drying methods available.