Prefabricated transformer compact substation which refer to as "box substation", is an equipment that integrates HV switchgear, distribution transformers, LV distribution devices combined according to specific wiring schemes. Due to its compact size, flexibility in site selection, and strong adapt-ability to environmental operation with low investment, it is widely acceptable for residential neighborhoods, industrial and commercial stations, hospitals, hotels , to be an complete power distribution system to users with voltage 12kV up to 40.5kV, and capacity up tp 2500KVA.