A power transformer is typically used at higher voltages and in transmission or bulk substation levels to transfer large amounts of power between different voltage tiers. A distribution transformer operates closer to end users, for example stepping medium voltage down to low voltage for homes or small industries. Power transformers are optimized for efficiency at or near full load, while distribution transformers are optimized for good efficiency at light to medium load where they operate most of the time. Their design, cooling, tap ranges and protections reflect these different roles in the system.