This when was the dominant variety of UPS and is also restricted to round the a hundred and fifty kVA range. These units are still primarily used in some industrial settings (oil and gasoline, petrochemical, chemical, utility, and weighty market markets) mainly because of the strong nature in the UPS. https://felixtdlty.topbloghub.com/40170612/the-definitive-guide-to-uninterruptible-power-supply-calculator