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Function description
Wieland Electric GmbH | BA001052 (Rev. A) | 11/2018
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5.1
UPS mode
Figure 5 UPS connection example
In UPS mode the UPS module protects a load from unwanted power interruption in case of mains failure.
An example of UPS connection is given in Figure 5.
When the input is present, the UPS module acts as a bypass, connecting the input to the output via the
input switch. Meanwhile, if required, the battery is charged. During bypass there is no voltage conversion,
therefore the output supply voltage is equal to the input voltage.
In case of power outage, the UPS module takes energy from the battery to keep the output regulated at
nominal output voltage. See no. 20 in section 6.2 for more details.
5.1.1
Backup (battery mode)
The system is in backup mode if the supply for the output is sourced from the battery (input supply
missing). During backup the battery is monitored continuously to prevent over discharge.
A
programmable backup timer
is also implemented in order to fix a maximum backup time during
power outages. This allows preserving the battery life and shortening the recharge time, avoiding dis-
charging the battery when not needed. See no. 24 in section 6.2 for more details.
During backup the internal Coulomb counter is used to give an estimation of the residual charge of the
battery.
Backup starts when the output voltage is lower than 90% of the nominal output voltage. See no. 20 in
section 6.2 for more details.
5.1.2
Battery health monitor
The battery health monitor is composed of:
•
Internal resistance measurement: The resistance is periodically measured. The internal resistance
is a good indicator of the battery health status; a sudden increase of the internal resistance indi-
cates a potential problem on the battery or on the battery wiring.
•
Temperature measurement: The battery temperature is monitored through an optional tempera-
ture sensor (
wipos
UPS 20 Sensor). The battery charger takes into account the battery tempera-
ture and provides a temperature compensated charging voltage. In case of over or under temper-
ature the system disconnects the battery to prevent damage.
•
Coulomb counter: Estimates the remaining battery capacity and consequently the available
backup time.
•
Deep discharge protection: It protects against the deep discharge of the battery which can lead
to its irreversible damage.
