ABB ACS880-304LC Series, Руководство по оборудованию, Страница: 18 / 178

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6-, 12- and 24-pulse supply units
The supply units can be connected either to 6-pulse, 12-pulse or 24-pulse connection.
If 12-pulse or 24-pulse supply transformer is used, there can be a maximum of 4 diode
supply modules in one drive system. The figure illustrates the difference between
6-pulse and 12-pulse AC supply connections. The 6-pulse connection is standard.
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.
6-pulse connection
1
2
3 4
5
12-pulse connection
1 2
3
4
5
Supply transformer 1
Switching equipment and fuses 2
Fuses for protecting input cabling 3
AC fuses for protecting supply unit against short circuit 4
Diode supply modules 5
18 Operation principle and hardware description