Fault-tolerant power systems that can support many different telecomm systems, as well as battery plant facilities, are derived by combining front-end rectifiers and 3U high subracks. The FE Power Shelf Series is scalable from 500W to 6000W and is available in 19" and 23" subracks, which can be paralleled to meet even larger power requirements. The series meets BellCore NEBS and ETSI standards and carries full safety agency approvals, including UL1950, CSA22.2-234, EN60950 and CE mark.The rectifiers are available in 500W, 1000W, 1500W and 2000W sizes with 24 or 48 vdc outputs and wide input ranges (85 to 265 vac for 500W to 1500W supplies and 170 to 265 vac for 2000W units). They come in three Power Shelf racking configurations, ranging from the FE4K that can hold up to eight FE 500W rectifiers and can deliver 48 vdc/100A or 24 vdc/200A to the FE6K that can hold three FE 2000W rectifiers with 48 vdc/150A or 24 vdc/273A. Other features of the series include hot-plug operation, remote diagnostics, overvoltage/overtemperature protection, and more.