... : Improve specification by performing Cost Oriented Valuation(1). As a rule: For better protection, Line Interactive type should be preferred over ... .(6). In redundant configuration, two or more units work in parallel, while at least one is a spare unit. Thus full ... 20kVA load, compare the cost of two parallel ups systems 20kVA each, to three parallel systems 10kVA each. (Common mistake assumes that ...