This UPS design is a relatively new technology that was introduced to eliminate the drawbacks of the Double Conversion On-Line design and is available from 5kVA and greater. Like the Double Conversion On-Line design, the Delta Conversion On-Line UPS always has the inverter supplying the load voltage. However, the additional Delta Converter also contributes power to the inverter output. Under conditions of AC failure or disturbances, this design behaves identically to the Double Conversion On-Line. During steady state conditions the Delta Converter allows the UPS to deliver power to the load with much greater efficiency than the Double Conversion design. A simple way to understand why this works is to consider the energy required to deliver a package from the 4th floor to the 5th floor of a building. It obviously saves energy to carry the package only the difference (delta) between the starting and ending points. The Double Conversion On-Line UPS converts the power to the battery and back again whereas the Delta Converter moves much of the power from input to the output directly. In the Delta Conversion On-Line design the Delta Converter can also charge the battery so the overall design is no more complex than the Double Conversion approach and it provides the same output characteristics. In addition, the Delta Conversion On-Line UPS offers reduction in energy losses and costs by approximately a factor of 4. As a side-effect of the design, the input power quality of the Delta Conversion UPS is also superior, particularly in the large kVA sizes.