ABB ACS880-304 +A018, Hardware Manual

Page: 21 / 280

Operation principle and hardware description 21
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6- and 12-pulse supply units
The figure below illustrates the difference between 6-pulse and 12-pulse AC supply
connections. The 6-pulse connection is standard. If the drive has an even number of
supply modules, you can order it as a 12-pulse version (A004).
The 12-pulse supply connection eliminates the fifth and seventh harmonics, which
remarkably reduces the harmonic distortion of the line current and the conducted
emissions.
The 12-pulse connection requires a three-winding transformer, or two separate
transformers. There is a 30-degree phase shift between the two 6-pulse supply lines,
which are connected to different supply modules through electrically separate switching
equipment.
No. Description
1. Supply transformer
2. Switching equipment
3. Diode supply modules
1 2
3
6-pulse connection
1 2
3
12-pulse connection