According to Excelsys, its Xgen modular power supplies are the quietest around—the new 200- and 400-W power chassis maintain 37.3 dBA of acoustic noise over all load conditions. The 200-W XTA and 400-W XTB chassis are certified to UL/EN60950 2nd edition, while the 200-W XNA and 400-W XNB chassis are certified to UL/EN60601-1 3rd edition medical approvals. Each 10.24- by 3.50- by 1.50-in. chassis contains four slots that can be configured with up to eight isolated outputs from 1.5 to 58.0 V dc. All user-adjustable outputs are able to be combined in series for higher voltages, or in parallel for higher currents. Efficiency is 89%. Other features include a 5-V dc auxiliary output, universal 85- to 264-V ac input, and full suite of protection (overvoltage, overcurrent, overtemperature, short circuit).