Type EY e-Rated® low voltage dry-type isolation transformers exceed all existing and pending energy efficiency requirements. Energy efficiency requirements are determined at 35% of the transformer’s full load (FL) rating. As a result, manufacturers generally optimize their transformers’ efficiencies at approximately 35% FL.
Type EY transformers’ ultra-low Excitation (no-load) Losses provide high efficiency during periods of light-loading (<15% FL). This benefit is achieved by using higher quality, grain oriented silicon core steel in the Unicore™ cores of lower kVA ratings and in the full and step-lap miter-cut cores, with reduced laminations per group, in higher kVA ratings.
Unlike Excitation Losses, which are constant from no-load to full-load, Impedance (load) Losses increase rapidly above 15% FL; particularly when the transformer’s loads are nonlinear. To maintain energy efficiency, Type EY e-Rated ® transformers’ peak efficiencies can be matched to anticipated or measured average loading above 35% FL.