Three-phase transformers are used whenever three -phase power is required, e.g. in the case of machines, air conditioners or welding equipment. Three – phase transformers are produced with a power rating of up to 100kVA for use as isolation transformers and up to 300kVA as autotransformers. Most of the materials used are UL -/ CSA approved. Additional system components, e.g. thermal circuit breakers, current limiters etc. are fitted to meetindividual requirements.