Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - Classic Control - Manual (Page 305)

Component Definition and Maintenance 6-15
7000 “B” Frame 7000-UM150I-EN-P – June 2013
Filter Capacitors
Filter capacitors are used on the motor side for all 18-pulse and
PWM rectifier drive options. The PWM rectifier option also includes
filter capacitors on the line side. Refer to Figure 2.6 (Cabling
Cabinet for 18-pulse Rectifier) and Figure 2.7 (Cabling Cabinet for
6-pulse/PWM Rectifier).
The filter capacitors are three-phase four-bushing units and “oil-
filled”. The three-phase capacitors are comprised of internal single-
phase units that are connected in an Y configuration. The neutral
point of the Y is connected to the fourth bushing, which is accessible
and can be used for neutral point voltage measurement or other
protection/diagnostics purposes. Depending on the drive
configuration, the fourth bushing may or may not be connected to a
circuitry. The metal cases of the capacitors are grounded through a
stud on the capacitor housing.
The capacitors are equipped with internal “bleeding resistors” to
discharge the capacitor and reduce its voltage below 50V in 5
minutes when left disconnected. A typical three-phase capacitor is
shown below:
Figure 6.13 – Motor Filter Capacitor
W A R N I N G W A R N I N G Allow 5-10 minutes for motor capacitors to
safely discharge voltage prior to opening
cabinet doors.
Filter Capacitor Cabinet