ABB ACS880-307LC, Руководство по оборудованию

Страница: 14 / 106

￭ Overview diagram of the rectifier bridge
U U
1
2
3
Diodes. The diodes connect the AC terminals in cyclic sequence to the lower DC busbar (-). 1
Thyristors. The thyristors connect the AC line terminals in cyclic sequence to the upper DC busbar (+). 2
AC chokes 3
￭ 6- and 12-pulse supply connections
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
substantially 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 must be phase shift of 30-degrees between the two 6-pulse supply lines, which are
connected to different supply modules through electrically separate switching equipment.
14 Operation principle and hardware description