Rockwell Automation 1305 AC Drive, Series C, Firmware 6.xx and Up - Manual (Page 23)

Installation/Wiring 2-9
GROUNDING
Refer to the grounding diagram on the following page. The
drive must be connected to system ground at the power ground
(GRD) terminal provided on the power terminal block (TB1).
Ground impedance must conform to the requirements of
national and local industrial safety regulations (NEC, VDE
0160, BSI, etc.) and should be inspected and tested at
appropriate and regular intervals. In any cabinet, a single,
low–impedance ground point or ground bus bar should be used.
All circuits should be grounded independently and directly.
The AC supply ground conductor should also be connected
directly to this ground point or bus bar.
Sensitive Currents
It is essential to define the paths through which the high
frequency ground currents flow. This will assure that sensitive
circuits do not share a path with such current, and to minimize
the area enclosed by these paths. Current carrying ground
conductors must be separated. Control and signal ground
conductors should not run near or parallel to a power ground
conductor.
Motor Cable
The ground conductor of the motor cable (drive end) must be
connected directly to the ground terminal, not to the enclosure
bus bar. Grounding directly to the drive (and filter, if installed)
provides a direct route for high frequency current returning
from the motor frame and ground conductor. At the motor end,
the ground conductor should also be connected to the motor
case ground. If shielded or armored cables are used, the same
grounding methods should be used for the shield/armor as well.
Discrete Control and Signal Wiring
DO NOT connect drive Common terminals (TB2) to ground.
DO NOT switch these inputs using non-isolated TTL type
circuits. Use dry relay contacts to switch signal inputs to
Common. Only isolated 4-20mA sources are recommended.
There must be no ground potential difference between source
and drive.
Safety Ground
This is the safety ground required by code. The ground bus can
be connected to adjacent building steel (girder, joist) or a floor
ground loop, provided grounding points comply with NEC
regulations.
RFI Filter
Important: Using an optional RFI filter may result in
relatively high ground leakage currents. The filter must be
permanently installed and solidly grounded. Grounding must
not rely on flexible cables and should not include any form of
plug or socket that would permit inadvertent disconnection.
The integrity of this connection should be periodically
checked.