Powerware 9170 User Manual page 64

Operation
The High Efficiency (H.E.) mode is a user-programmable automatic
mode of operation. This mode allows power to flow through the internal
UPS bypass path for as long as AC input stays within the user-defined
setpoints. If the input voltage or frequency deviates beyond these
setpoints, the Powerware 9170 system transfers to the Double
Conversion mode of operation. Complete loss of input voltage causes
the UPS to transfer to Battery mode. While in H.E. mode, the Powerware
9170 system provides passive EMI filtering in the power path.
Off mode turns off the output and most internal circuitry. Within this
mode, another mode (Sleep) turns off all internal circuitry when AC line
is not present and battery voltage drops to a low threshold. If AC input
voltage is not present in Off mode, the user can direct the UPS to enter
Sleep mode by selecting the Battery Protect (BP) feature. When AC
input voltage returns in the Off mode (caused by a low battery alarm
condition), the UPS automatically recovers and, if the Auto Restart
parameter is enabled, switches to Double Conversion. Auto Restart is
enabled as a factory-default.
The UPS will not automatically recover from the Sleep mode, regardless
of the state of the Auto Restart parameter.
Figure 46 shows the basic functional elements of the UPS.
Input
(Utility)
Line/Battery
Power
Relay
EMI/RFI
Filter
Battery
Modules
(Parallel)
Figure 46. Powerware 9170 UPS Functional Block Diagram
60
Bypass Relay
Input Power (Boost)
Converter
Battery Charger
DC/AC Power Inverter
Internal DC
Power Bus
Capacitor Bank
Powerware 9170 User's Guide
®
Isolation
Transformer
(Optional)
Output Relay
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