Salicru SLC CUBE 3+ PS Mode D'emploi page 106

4.2.2. Structural diagram.
To describe the operating principle, it is taken as a reference and
example the single line diagram of Fig. 25 and 26, corresponding to
SLC CUBE3+ PS with three phase input and output setting, one
with basic structure and the other one with separate bypass line.
All the equipments works and operates in the same way, although
they have common line or separate static bypass.
4.3. UPS FUNCTION STAGES.
SLC CUBE3+ PS UPS series is structured in the following
stages:
I/O EMI filters.
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Rectifier-PFC (AC/DC).
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Batteries.
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Inverter (DC/AC).
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Static Bypass.
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Maintenance or manual Bypass.
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EPO emergency shutdown.
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Control panel.
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Control and communication Software.
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4.3.1. I/O EMI filters.
EMI filter is a three phase low-band filter, which its function is to
attenuate and cancel all the radio frequency perturbations. The
filter performs in a bidirectional way:
It cancels the perturbations that comes from the line and pro-
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tect the UPS control circuits.
It avoids the possible radio electrical perturbations that the
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UPS could generates flows through the line and affect to other
equipments connected to it.
4.3.2. Rectifier-PFC stage (AC/DC).
Constructive parts:
Input protection and switch: it is the particular protection
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of the PFC rectifier.
Current sensor: it uses alternating current transformers to
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measure and control the input current, to get a THDi < 3% at
full load condition and even < 1% depending on the quality of
mains.
"T" filter: it is used to attenuate the current ripple caused by
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the PFC switching.
IGBT's three phase bridge: it will be used to make the AC/
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DC conversion with the lowest distortion and highest effi-
ciency. To do that, it is used the Trench-gate IGBT technology
of 4th generation.
Input chokes: They are used by the PFC rectifier as energy
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storage elements (in switching times), for the AC/DC conver-
sion.
DC Bus: it is used to filter the DC needed for the correct opera-
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tion of PFC converter and inverter.
106
4.3.3. Batteries.
SLC CUBE3+ PS UPS series has a battery set that stores energy
during the normal operating mode (present mains) and they are dis-
charged during the emergency operation (mains fault), keeping the
critical loads running during the required time.
Batteries are sized to supply full power to the assigned critical loads
during the back up time for any load condition. Standard batteries
are sealed Lead Acid, maintenance free and VRLA technology.
Each cell or cell group (battery block) are duly marked in a perma-
nent way, with polarity indication, voltage and safety warning re-
quired by the standard.
Cells are duly assembled and electrically connected. Battery set
is protected by means of a fuse holder with ultra fast fuses, ready
for the described conditions in section «4.3.2. Rectifier-PFC stage».
In normal operation (mains present and charged batteries), the bat-
tery set is working on floating voltage.
As an option the battery set of Pb-Ca or Ni-Cd can be assembled
in a cabinet or rack separately from the equipment, shared for sys-
tems made of two UPSs in parallel.
4.3.4. Inverter stage (DC/AC).
Constructive parts:
DC Bus: it is used to filter the DC and it is in charge of inter-
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connecting the PFC and Inverter through the protection fuses.
IGBT three phase inverter bridge: it is equal to the PFC
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stage but in counter way, it is in charge of making the DC/AC
conversion with the lowest distortion and highest efficiency.
It is also using the Trench-gate technology of 4th generation.
Current sensor: as it has been described before, in this case
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conventional AC currents sensors are also used (current trans-
formers) for measurement and control the output current of the
inverter to get a total harmonic distortion at the output voltage
lower than 1% in full load conditions.
Output chokes: it is used an identical solution as the used
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at the input. These chokes are used by the inverter as energy
storage elements (in switching times), for DC/AC conversion.
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