When sourcing Kva transformers, buyers must prioritize rated capacity (kVA), voltage ratio (e.g., 11kV to 415V), and winding material. High-quality transformers typically use 100% electrolytic copper windings for superior conductivity and lower losses, though aluminum is a cost-effective alternative for specific applications. Additionally, verify the insulation class (Class F or H) and the cooling method (ONAN for oil-immersed or AF for dry-type) to ensure the unit matches your operational environment.