3BHS799208 E01 REV E ACS5000 WATER-COOLED USER MANUAL 57/186
03 POWER ELECTRONICS AND CABINET FEATURES
3.7 EXU – Excitation unit (optional)
The EXU supplies a synchronous motor with excitation power. The EXU is 
available for the following excitation methods:
• Brush excitation (DC excitation): Brush excitation uses a DCS800 AC-
to-DC converter (see figure below) which is supplied by the mains. 
The converter controls the direct current for generating the 
magnetic field. Brushes and slip-rings feed the DC current to the 
rotor.
• Brushless excitation (AC excitation): Brushless excitation uses a 
three-phase DCS800 AC-power controller (see figure below). The 
power controller feeds an exciter which is mounted on the shaft of 
the main motor. The rotating armature of the exciter supplies a 
rectifier which generates the DC current for producing the 
magnetic field in the synchronous motor.
Figure 3-19 EXU
(1) AC-to-DC converter
(2) Output disconnector (option)
(3) AC power controller
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