14 Theoryof Operation
Figure 6 UPS Module Block Diagram
UPS Module
TheUPS module consists of module controls, a rectifier/charger,an inverter, protective devices, and other acces-
sories.
ModuleC ontrols: The module controllogic monitors performance of the UPS module.T heUPS module status
isdisplayed locally and is also sent to the System Control Cabinet.
Rectifier/Charger:The rectifier/chargerconverts utility power from AC to DC to charge the battery and pro-
videthe DC input to the inverter. Its design limits reflectedharmonic current distortion to source power and pro-
videslow-ripple DC power for charging batteries. Multiplerectifier/chargers can share a common battery plant,
ifthat configuration is preferred for your application.
Inverter: The inverter converts DC power intothe precise AC power required to supply a sensitive critical load.
Theinverter converts DC power into a pulse-width-modulated (PWM)/six-step waveform that ise asilyfiltered
intoa clean sine wave output. The PWM/stepwave also minimizest he harmonicvoltage distortion caused by
typicalswitching power supplies and other non-linear load componentsused in computers and related electron-
ics.
Battery Plant
Thebattery is used as the alternate source of power to supply DCpower to the inverter if the AC supply voltage
isoutside the acceptable range. The battery suppliespower to the inverter until the utility power isrestored or
untilan alternate power source is available.If AC source power is not restored or an alternate power source is not
available,the battery can be sized to provide power long enough for an orderly shutdownof the load.
CB- Circuit Breaker
MBD- Module Batte ry Disconnect
SCC- SystemCont rol Cabinet
Rectifier/
Charger
Controls
CONTROLPOWER
MULTI-MODULE UPS SYSTEM
Inverter
MBD
Utility
Input
Power
Control
Wiring
ToSCC
Battery
Output
Power
ToSCC
Output
CB
Input
CB
DISCONTINUED
PROD U C T