
8-25
Operating the Drive
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames E & F
12-Pulse Systems
12-pulse drives are used:
♦
for very large horsepower applications
♦
to reduce harmonic distortion
A 30 degree phase shifting transformer is used. A characteristic of the phase shifting is to cause the 5
th
, 7
th
,
17
th
, 19
th
, etc. harmonics to cancel and this results in reduced line harmonics.
The phaseshift transformer
MUST
be of the type to
deliver matched output
voltages, otherwise the
current in the two 890CS
units will be imbalanced.
X02/03 ENABLE
L1
L2
L3
X02/01 +24V OUT
X02/03 ENABLE
DC+
DC-
identical chokes
identical drives
890CD Frames E & F
890CS
890CS
X02/01 +24V OUT
DELTA
STAR