All 3-Phase UPS Systems, regardless of the manufacturer, generate some level of THDi. It is produced by the normal operation of the UPS's internal rectifier components (the place where the UPS converts incoming AC into DC power). From the rectifier, THDi is conducted back up the input line (through cabling and distribution panels) toward the utility or generator source. While most newer designs of 3-Phase UPS Systems have relatively low voltage input THDi, the level of input current THDi varies widely. If the current THDi is high, managers are forced to oversize everything that distributes power to the UPS: generator, input distribution panels, and cables. If managers install a UPS that generates lower input current THDi, it can save significant installation costs and gain better interactive performance with the utility and generator sources.