KSTAR EPI / Master transformer online UPS, 6–40 kVA, 3:1

Technical specifications

Specifications are taken from the manufacturer’s technical documentation. Updated 11/06/2026.

Description

Both series are built on the online topology with an isolation transformer, so the load is fed from the inverter and is galvanically separated from the mains. The Master has an input range of 304–456 V AC, suited to networks with noticeable line voltage deviations. The power factor differs between the series. For the EPI it reaches 0.97 at the input, so the network sees an almost resistive load and the feeders and generator carry less reactive current. For the Master 0.8 is stated, and active power should be calculated from this value rather than from the full kVA. A transformer design is heavier than a transformerless one, but it gives galvanic isolation without extra devices. This kind of UPS goes where a power failure stops the process.

How to choose

First calculate the load's active power, since at 0.8 it is noticeably lower than the full kVA. If you need a 6 kVA UPS, only the Master fits, since the EPI starts at 8 kVA. For a compact rack/tower unit of 6–10 kVA with the same 3:1 phasing there is the UCR. If both input and output must be three-phase, look at the UD, 10–80 kVA.