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In bypass mode, the output of the system is provided with three-phase AC power directly from
the system input. While in this mode, the output of the system is not protected from voltage
or frequency fluctuations or power outages from the source. Some power line filtering and
spike protection is provided to the load but no active power conditioning or battery support is
available to the output of the system in the bypass mode of operation.
The internal bypass is comprised of a solid-state, silicon-controlled rectifier (SCR) static switch
(SSW). The static switch is rated as a continuous-duty devfice that fis used any tfime the finverter
is unable to support the applied load. The statfic swfitch,befing an eflectronficaflfly-controflfled
device, can be turned on fimmedfiatefly to pfick up the fload from the finverter whfifle the finverter
output contactor K3 opens to fisoflates the finverter.
4.2.3 Battery mode
The UPS automatically transfers to battery mode if a utility power outage occurs, or if the
utility power does not conform to specified parameters. In battery mode, the battery provides
emergency DC power that the inverter converts to AC power.
Figure 4-4 shows the path of electrical power through the UPS system when operating in
battery mode.
Figure 4-4. Path of current through the UPS in battery mode
44
UPS 200 kVA
User's and Installation Guide
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