Grounding
3-5
Figure 3.4 Fully Grounded Scheme
The installation and grounding practices to reduce common mode noise
issues can be categorized into three ratings. The scheme used must weigh
additional costs against the operating integrity of all scheme components. If
no sensitive equipment is present and noise is not be an issue, the added cost
of shielded cable and other components may not be justified.
Acceptable Grounding Practices
The scheme shown below is an acceptable ground layout for a single drive
installation. However, conduit may not offer the lowest impedance path for
any high frequency noise. If the conduit is mounted so that it contacts the
building steel, it is likely that the building steel will offer a lower impedance
path and allow noise to inhabit the ground grid.
Earth Ground Potential
X
0
R
S
T
U
V
W
PE
PE
AC DRIVE
Panel Ground Bus
INPUT TRANSFORMER
(OPTIONAL ENCLOSURE)
MOTOR
MOTOR FRAME
S
T
R
A
P
CONDUIT
BUILDING GROUND POTENTIAL
A
B
C
PE
Connection to
Ground Grid,
Girder or
Ground Rod
Connection to
Cabinet Ground Bus
or Directly to
Drive PE Terminal
Incidental Contact
of Conduit Strap
Motor
Frame
Ground
Connection to Drive Structure
or Optional Cabinet
Via Conduit Connector
Summary of Contents for Allen-Bradley 1305-AA02A
Page 4: ...ii Summary of Changes Notes ...
Page 40: ...2 18 Power Distribution Notes ...
Page 48: ...3 8 Grounding Notes ...
Page 68: ...4 20 Practices Notes ...
Page 78: ...6 8 Electromagnetic Interference Notes ...
Page 94: ...Glossary 4 UL Underwriters Laboratories ...
Page 100: ...Index 6 ...
Page 101: ......