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5.3. When Utility is Abnormal/Absent
The working principle of the UPS under Utility abnormal condition is illustrated
as follows
：
1. When Utility is abnormal, the UPS will direct the battery energy automatically to
the Inverter without delay, and turn off the charger and AC/DC converter. The
inverter revert DC to AC to supply energy to the output load connected without
interruption. The
LED will be illuminated.
2. When Utility is back to Normal, the UPS will turn on the AC/DC converter, turn
off DC/DC converter and switch the charger to charging mode. It has the same
working principle as figure 5.2.
3. During a utility outage, the UPS will work as illustrated in figure 5.2. When
Battery is low, buzzer will beep continuously till battery is completely cut off.
The battery low protection of the UPS will cut off battery supply after a preset
threshold to avoid the battery from over-drain. The
&
(Battery Low)
LEDs will light up till the UPS is completely cut off. The UPS will re-start
automatically when Utility is available.
Fig 5.3
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5.4. Overload Condition
The working principle of the UPS when overloading is illustrated as follows
：
1. Generally modern day electronics & IT equipment generate an inrush current
when switching on. The amount of inrush current varies from equipment to
equipment, some can be as high as 6 times its rated capacity while others
produce negligible inrush. To prevent severe damage to its Inverter cause by
the inrush produce by the loads, the UPS is equipped with electronics overload
protection feature as standard. If the UPS loading is >105~120% of its capacity,
it will switch to bypass mode in 30 seconds to protect the Inverter. If overload
condition is eliminated by reducing the load to <105%, the UPS will switch back
to Inverter mode automatically. If the UPS is over 150% loading, it inverter will
shutdown immediately.
Fig 5.4