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Appendix A. Specifications
reverse during times when the input AC power is normal. When the input power fails the
transfer switch opens and the power flow is from battery to the UPS output. The fact that the
inverter is always connected to the output provides additional filtering and yields reduced
switching transients
Line-interactive UPS systems use automatic voltage regulation (AVR) to correct abnormal
voltages without switching to battery. (Regulating voltage by switching to battery drains your
backup power and can cause batteries to wear out prematurely.) The UPS detects when
voltage crosses a preset low or high threshold value and uses transformers to boost or lower
the voltage by a set amount to return it to the acceptable range.
In "line" mode (i.e. when not operating from battery), line-interactive UPS systems typically
regulate output within ±8 – 15 % of the nominal voltage (e.g. 120, 208, 230 or 240 volts). On-
line UPS systems typically regulate voltage within ±2 – 3 %.
During an outage, line-interactive UPS systems typically transfer from line power to battery-
derived power within two to four milliseconds, which is more than fast enough to keep all but
a small percentage of the most power-sensitive equipment operating without interruption.
When operating from battery power, a line-interactive UPS system generates the waveform of
its AC output.
Line interactive UPS units protect for 5 common power issues – Power Failure, Power Sage,
Power Surge, Under voltage, and Over voltage.
Power failure
Under voltage
Attention! When operating any of the 8 kVA or 11 kVA UPS units in HE (High Efficiency) Mode then
these UPS units work as line-interactive UPS units. In this case it is strongly
recommended to install frequency and voltage stabilisers as line-interactive UPS units can
not compensate for all utility power problems and may get damaged!
6U Rack or Tower UPS RT8kVA and RT11kVA IUOMG
Power sag
Over voltage
Power surge
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