APC 2000XL - Manual (Page 4)

Page 2
1.0 Introduction
1.1 Overview
This equipment is a high performance line interactive uninterruptible power source
(UPS) designed to provide clean, reliable AC power to computer loads. The UPS's line
interactive circuit topology, illustrated below, offers excellent efficiency, on-line voltage
regulation and fast utility fault response.
The UPS’s DC-to-AC inverter is always connected to the output and when operating on-
line, a portion of the inverter circuitry is put to work “in reverse” to continuously
maintain optimum float charge on the battery. The inverter circuitry also acts to protect
the load from surges and EMI/RFI noise as part of an advanced hybrid surge suppression
and filtering network. A unique mode of operation, named SmartBoost, serves to regulate
the load voltage by compensating for brownouts or sags. This is accomplished without
the need to draw power from the UPS’s battery. In anticipation of utility failure, the UPS
continuously monitors the line and prepares the inverter frequency for synchronous
transfer of the load. Upon occurrence of utility voltage failure such as a blackout, severe
brownout or an overvoltage condition, the UPS transfers the load to power derived from
the battery. Transfer to the "on-battery" mode of operation takes place typically within
2 milliseconds. The inverter's output voltage waveshape is a low distortion sine wave.
Resynchronization and retransfer to on-line operation is automatic upon recovery of the
line voltage to within normal limits.
Line interactive UPS block diagram