OnLine Power Power Wave 4 - Manual (Page 20)

6005-145 Rev. A 1-9
In order to further improve the power factor and reduce harmonic current drawn
by the rectifier, ELI at 120KVA and above, use the 12-pulse full controlled
rectifier. The total current harmonic current can be reduced to around 15%, and
power factor improved to over 0.8. A phase shift transformer is added to achieve
this performance. The input inductor is retained also to obtain the best result.
Although this results in higher cost, the unit is much more reliable and rugged.
Users do not need to increase the input breaker and cable sizes, since input KVA
and harmonic current drawn is minimized, fulfilling the worldwide energy
saving requirements.
The harmonic current can be further lowered by adding harmonic filters (factory
installation available). The total harmonic current can be reduced to
approximately 9%.
Another alternative method to reduce the harmonic current (especially for very
large KVA unit) is to employ 18-pulse full controlled rectifier (available as an
option). The total harmonic current can be reduced to approximately 7%.
12-PULS E FULL CONTROL RECTIFIER
INPUT
RECTIFIER
BREAKER INDUCTOR
CAPACITOR
SCR
AC
OUTPUT
DC
SCR
PHASE SHIFT
TRANSFORMER