Rockwell Automation 1336T Wiring and Grounding Guide, (PWM) AC Drives User Manual
Page 52
52
Rockwell Automation Publication DRIVES-IN001M-EN-P - March 2014
Chapter 3 Grounding
The grounding scheme can greatly affect the amount of noise and its impact on
sensitive equipment. The power scheme is likely to be one of these three types:
•
Ungrounded scheme
•
Scheme with high resistance ground
•
Fully grounded scheme
An ungrounded scheme (
) does not provide a direct path for the
common mode noise current, causing the current to seek other uncontrolled
paths. This causes related noise issues.
Figure 16 - Ungrounded Scheme
A scheme with a high resistance ground (
) provides a direct path for
common mode noise current, like a fully grounded scheme. Designers that are
concerned with minimizing ground fault currents commonly choose high
resistance ground schemes.
Figure 17 - Scheme with High Resistance Ground
A fully grounded scheme (
) provides a direct path for common mode
noise currents. The use of grounded neutral systems is recommended for these
reasons:
•
Controlled path for common mode noise current.
•
Consistent line-to-ground voltage reference that minimizes insulation
stress.
•
Accommodation for system surge protection schemes.
Earth Ground Potential
Earth Ground Potential
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