Filter
Top Products
14
Chapter Four: The Working Principle of the UPS
4.1. When Utility is Normal
The working principle of the UPS under normal Utility conditions is illustrated
as follows:
When Utility is normal, the AC source is rectified to DC, partially fed into the
charger to charge the battery and partially fed into inverter. The inverter
reverts the DC to AC to supply energy to the output load. The Utility LED
and Inverter LED will illuminate.
4.2. When Utility is Abnormal
The working principle of the UPS under abnormal Utility conditions is
illustrated as follows:
When Utility is abnormal, the UPS will direct the battery energy to the
Inverter. The charger and AC/DC converter will turn off. The inverter will
revert the DC to AC to supply power to the output load. The Inverter LED
will illuminate.
O/P
OUTPUT
--- 4-1 ---
RECTIFIER
O/P
OUTPUT
--- 4-2 ---
15
When the Utility power returns to normal, the AC/DC converter and the
charger will turn on. The DC/DC converter will turn off. It has the same
working principle as figure 4.1.
During a blackout, the UPS will work as illustrated in figure 4.2. When the
battery is low, the alarm will beep continuously until the battery is depleted
and the UPS shuts down. The Low Battery Cut-Off protection turns the
UPS off to prevent discharging batteries to an unsafe level. The Inverter
LED and the Battery Low LED will be illuminated until the UPS shuts down.
The UPS will Auto-Restart when the Utility power returns to normal. This is
the same working principle as figure 4.1.
4.3. Overload Condition
The working principle of the UPS when overloaded is illustrated as follows:
Normally, an inrush current is generated when turning on the connected
equipment.
If the UPS is 105~120% loaded, it will switch to the Bypass mode in 60-
seconds.
If the UPS is 120-150% loaded, it will switch to the Bypass mode in 10-
seconds.
If the UPS is over 150% loaded, it will switch to the Bypass mode
immediately.
The Utility LED, the Bypass LED and the Overload LED will be illuminated.
If overload condition is removed the UPS will switch back to the On-Line
mode automatically.
O/P
OUTPUT
--- 4-3 ---