Powerware 9170+ - Manual (Page 63)

59 Powerware ® 9170 User's Guide S LTM-1344 B Uncontrolled Copy
C H A P T E R 7
O
PERATION
The Powerware 9170 UPS operates in several different modes. Normally
it operates under internal control, called Auto mode, to automatically
protect loads connected to it. It also functions under operator control to
enable manual override should servicing or testing be required.
Figure 45 is an illustration of the operating modes. In Auto mode, the
UPS automatically switches between modes depending on line and load
conditions.
Double Conversion
(Line Conditioning)
Internal Bypass
Battery Off
Figure 45. UPS Operating Modes Under Auto Mode Control
Double Conversion mode produces output power from the internal DC
bus. The AC input power is rectified and boosted to supply this DC bus.
The UPS switches automatically to and from Battery mode with no
interruption (0 ms transfer time) as AC input power drops and returns.
Batteries are charged in this mode.
Battery mode produces power from the batteries to supply the internal
DC bus.
Internal Bypass (Bypass) mode shunts power flow around the DC/AC
internal circuitry to keep the output powered with no line conditioning.
Electromagnetic interference (EMI) and surge circuitry still protect the
loads from voltage spikes and noise.