DC UPS
This DC Power system
is designed to supply DC electric power that is protected from abnormal
occurrencess on the public electricity supply. A voltage dropper is a
controlled voltage stabilizing device. It is used for maintaining the voltage
at the load within a given range of typical +/- 10% of the nominal voltage, if
the voltage range of the connected battery is larger than the voltage range of
the connected load.
Figure 1.
Block Diagram DC UPS
The equipment always consist of two
independent systems with a common distribution board. Each half system consist
of two major part.
Figure 2.
Block Diagram Rectifier /chargers and the Batteries.
In order to observe
the given output voltage range, the diodes are activated in flow direction, if
the battery charge voltage is too high; or deactivated, if the battery
discharge voltage is too low. This is controlled by means of maximally 4 diode
stages.
Rectifier
Charger
Converts the Primary AC supply to regulated
DC voltage which charges the battery, powers the inverter and therefore the
load. It operates in four possible modes,
float mode, AC supply fail mode, Charge mode, Boost mode.
Battery
This storage energy from the charger
to be used during a power cut when it will discharge to power the load. The
autonomy of the system during a mains fail depends on the amp-hour capacity of
the installed battery. Since the 2 chargers/batteries are independent of each
other, the mode of one is linked ia the distibution board to the other.
Figure 3.
Normal Mode
If only one charger supply fails, the
other charger will continue to feed the load. If both charger supplies fail,
both charger are stopped and the batteries feed the load
Figure 4.
Primary AC Supply Fail Mode
The charger stops and the
battery powers the load. The DC voltage falls and the following alarms. When
the primary AC suply returns the charger will start in float mode after a short
AC supply failure or charge mode after a long AC supply failure.
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