HPS drive isolation transformers, are designed to meet the rugged demands of both AC and DC variable speed drives and also provide the required voltage change. The separate primary and secondary windings provide electrical isolation between the incoming line and the SCR load. The windings are designed to withstand over current of 150% of the rated load for 60 s or 200% of the rated load for 30 s. Drive isolation transformers are sized to match standard motor horsepower and voltage ratings. Standard sizes range from 5 to 600 hp in 6 standard voltages.