Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 72)

2-42 Drive Installation
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
Grounding Practices (cont.)
ISOLATION
TRANSFORMER AC
MOTOR
U (T1)
V (T2)
W (T3)
2U
2V
2W
GROUND BUS
Connected to the neutral point
of the output capacitor
OUTPUT
GROUND
NETWORK
Figure 2.27 – Ground Connection Diagram with Isolation Transformer
AC
MOTOR
U (T1)
V (T2)
W (T3)
2U
2V
2W
GROUND BUS
AC LINE
REACTOR
TRANSFORMER
Connected to the neutral point
of the output capacitor
GROUND
FILTER
AC
MOTOR
U (T1)
V (T2)
W (T3)
2U
2V
2W
GROUND BUS
AC LINE
REACTOR
TRANSFORMER
Connected to the neutral point
of the output capacitor
GROUND
FILTER
Figure 2.28 – Ground Connection Diagram with Line Reactor
Each power feeder from the substation transformer to the drive must
be provided with properly sized ground cables. Utilizing the conduit
or cable armor as a ground is not adequate.
Note that if a drive isolation transformer is used, the WYE secondary
neutral point should not be grounded.
Each AC motor frame must be bonded to grounded building steel
within 6 m (20 feet) of its location and tied to the drive's ground
bus via ground wires within the power cables and/or conduit. The
conduit or cable armor should be bonded to ground at both ends.