Fabrication and Analysis of Parallel Uninterruptible Power Supply with Single Battery Bank

Abstract

Imperfection in utility supply like fluctuation, frequency variation, phase imbalance, long interrupt, harmonic, noise, flickering etc. A critical load required continues and reliable power no any interruption in power Uninterruptible Power Supply (UPS) are such Power conditioning devices used to provide uninterrupted, reliable and high-quality power for sensitive loads. A UPS provides backup power circuit to provide continues power when a power outage. Since one of the most important component in a UPS is the battery bank and it is costly. So, by using a parallel redundancy in uninterruptible power supply system with a single battery bank where two or more UPS share the same battery bank to reduce the cost and increase percentage availability of UPS. Here both units are must be capable to supporting the full load but they are connected in parallel and if one unit fails the other takes the full load. As a conjoined system, each UPS stands ready to take over the load from another UPS whenever necessary, without disrupting protected loads. This is achieved by either a master/slave configuration where the one unit is in standby mode and is only switched in when the master unit fails or by current sharing which requires expensive electronics or transformers. This arrangement has a lower systems probability of failure compared to the isolated redundant scheme as all the UPS systems are online and supporting the load at all time. Thus, there will be no sudden load step during changeover. However, as all the UPS modules require synchronization between them, they need to be the same design, manufacturer, rating and technology. Due to this mean time between failure (MTBF) is decreased and percentage availability is increased.