The range consists of transformers complying with following specification: 3- phase transformer for indoor or outdoor step down/step-up type rated frequency; 50 hz maximum ambient temperature ;/40 c temperature rise: oil 60° c winding:65° c mineral oil immersed ONAN type natural cooling vector group: dy11 input voltage; 415v/ 23v insulation (Kv)7.2/12 2 earthling terminal on cover.