The EPS system researched and manufactured by SIGA Company is mainly made of rectifiers, static switch modules, and manual bypass switching, control cells, retransformation equipment, machine framing, storage batterys .retransformation equipment is core. The action of the rectifier is to change AC into DC to provide charging for storage batteries and supplying electricity to retransformation modules. The retransformation equipment change DC into AC to supply electric power load equipment that is stable and constant. Static switching can be set up to mothball or using on line working modes and adjust the output of retransformation equipment and municipal electricity at the same time to ensure the load is smoothly changed between them. Manual bypass can switch can change the load into municipal electricity and isolate with system. In this way it isnt possible to block the normal work of load equipment when maintaining the system. There is a monitor of the whole system which can give an alarm, at the same time; it is possible to connect the serial mouth with a computer or modem to provide long-range monitoring of an electrical supply system