OnLine Power Battery Backup System - Manual (Page 13)

OLP
Three Phase UPS Systems
1. SYSTEM OVERVIEW
1-9
PHASE SHIFT
TRANSFORMER
DC
OUTPUT
CAPACITOR
SCR RECTIFIER
BREAKERINDUCTOR
AC
INPUT
SCR
12 PULSE FULL CONTROL RECTIFIER
In order to further improve the power factor and reduce harmonic current drawn by
the rectifier, UPS systems rated 80KVA and above use the 12-pulse full controlled
rectifier. The total current harmonic current is reduced and power factor improved to
over 0.8. A phase shift transformer is added to achieve this performance. An input
inductor is retained also to obtain the best result. The use of 12 pulse rectification
distributes the rectification work load over more devices and increases the reliability of
the overall system. There is no need to increase the input breaker and cable sizes, since
input power and harmonic current drawn is minimized, fulfilling the international
energy saving requirements.