UPS Working Principle
UPS-Manual
22
EN
5.3. When Mains is Absent
The working principle of the UPS under Mains
absent condition is illustrated as follows:
1. When Mains absent, 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 con-
nected without interruption. The
(Nr. 5)
LED only
will be illuminated
.
2. When Mains 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 Power outage, the UPS will work as
illustrated in figure 5.3. 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
LED & symbol in
LCD will light up till the UPS is completely cut
off. The UPS will re-start automatically when
Mains is available.
5.4. Overload Condition
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 protec-
tion 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 In-
verter. 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.
2. The UPS Bypass loop is also equipped with
overload protection. Its overload capacity is
illustrated by the graph & table below.
5.5. Inverter Failure
5.5.1. Output Load short circuit when
supply via inverter
If output load is short circuited while supply via
Inverter, the UPS will shutdown Inverter auto-
matically and stop supply to the loads. The
Fault LED lights up and the buzzer will beep
continuously. The UPS will not switch on auto-
matically after short circuit condition is elimi-
nated. The UPS has to be re-start manually
(refer to ‘Start Up in Normal AC Mode).
0
50
100
150
200
250
300
110
115
120
125
130
135
140
145
150
Last in %
t in sec.
0
1
2
3
4
5
6
146
156
166
176
186
196
Last in %
t in sec.
Load in %
Load in %
