Back-up uninterruptible power system.

摘要

A back-up interruptible power system has a power supply path from input terminals connected to AC power system lines to normally supply power to a load. Upon the occurrence of a line fault, a static switch in the power supply path interrups the connection between the AC power lines and the load and an inverter is turned on to provide derived from an auxiliary battery through a transformer to the power supply path to supply AC power to the load. By using the static switch, switching from line connection to backup power can be done quickly, within a half cycle, so that substantially no interrruption of the output waveform is observed. The inverter can be operated to provide a communication pulse to the SCRs in the static switch. Line fault detection is carried out by creating a digital waveform composed of an average of prior cycles of the AC input waveform.