Rockwell Automation 7000A PowerFlex Medium Voltage Drive (A-Frame) - Classic Control - Manual (Page 356)

6-52 Component Definition and Maintenance
7000A-UM150F-EN-P –June 2013 7000 “A” Frame
Filter Capacitors
Filter capacitors are used on the motor side for all drives. The PWM
rectifier option also includes filter capacitors on the line side. Refer to
Figure 6.42 (DC Link and Fan Cabinet with control panel removed).
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 a 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 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:
Line Filter Capacitor
(with PWM Rectifier only)
Motor Filter Capacitor
Line Filter Capacitor
(with PWM Rectifier only)
Motor Filter Capacitor
Figure 6.45 – 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.
Generator Note:
W A R N I N G W A R N I N G Verify that the load is not turning due to the
process. A freewheeling motor can generate
voltage that will be back-fed to the equipment
being worked on.