Classification of Transformers 
according to number of phases : 
1- single phase transformer
2- poly phase transformer
according to frequency : 
1- very low frequency transformer
2- audio frequency transformer
3- high frequency transformer
4- IF frequency transformer
 according to turns ratio:
1- stepup transformer
2- stepdown transformer
according to thier function :
1- power transformer
2- distribution transformer
3- voltage transformer
4- current transformer
