GE Industrial Solutions LP11 924 Series 6 & 10 kVA - Manual (Page 10)

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OPM_LPU_11U_6K0_10K_1US_V010.Doc 9 User manual LP11 924 6 & 10 kVA UPS 1.0
3 – FUNCTIONAL EXPLANATION
3.1 - THE PRINCIPLES OF OPERATION
The UPS stores electric energy in batteries. This allows the UPS to supply output power even when the incoming utility
power is cut off completely.
Energy is stored as Direct Current (DC), while input and output energy must be Alternating Current (AC). Therefore the UPS
contains an input converter (AC to DC) and an output converter (DC to AC). (fig.2)
3.2 - NORMAL CONDITIONS
Under normal conditions, energy from the utility is channeled through the input converter, which supplies the output
converter and the battery charger. The batteries are kept in a fully charged state, and the output converter synthesizes a
completely new AC output sine wave to supply the load (electrical equipment).
Figure 2: Block diagram of the LP11 924 UPS, utility present
3.3 - UTILITY FAILURE
In the event of a utility power failure (i.e. absent or outside tolerance) the system uses the energy reserve stored in the
battery to continue to produce AC power, ensuring unbroken output (fig. 3). No interruption or alteration will ever be
noticed in the output power.
In the event of an extended utility failure (greater than 90 minutes), the output converter will stop when the battery has
been discharged. At this point, the UPS is no longer able to power the connected equipment.
When the utility is re-established within tolerance, the output converter will be supplied again by the input converter and
the batteries will be recharged, making them ready to support future power failures.
Figure 3: Block diagram of the LP11 924 UPS, utility failure