Rockwell Automation 1398-DDM-xxx ULTRA 100 Series Drives Installation Manual - Manual (Page 275)

Publication 1398-5.2 – PDF 1997
Electromagnetic Compatibility Guidelines for Machine Design E-2
Immunity to EMI is primarily determined by equipment design, but
how you wire and ground the device is also critical to achieving EMI
immunity. Therefore, it is important to select equipment that has been
designed and tested for industrial environments. The EMI standards
for industrial equipment include the EN61000-4-X series (IEC 1000-
4-X and IEC801-X), EN55011 (CISPR11), ANSI C62 and C63 and
MIL-STD-461. Also, in industrial environments, you should use
encoders with differential driver outputs rather than single ended
outputs, and digital inputs/outputs with electrical isolation, such as
those provided with optocouplers.
The EMI model provides only three options for eliminating the EMC
problem:
●
reduce the EMI at the source,
●
increase the victim’s immunity to EMI (harden the victim), or
●
reduce or eliminate the coupling mechanism.
In the case of servo drives, reducing the EMI source requires slowing
power semiconductor switching speeds. However, this adversely
affects drive performance with respect to heat dissipation and speed/
torque regulation. Hardening the victim equipment may not be
possible, or practical. The final, and often the most realistic solution is
to reduce the coupling mechanism between the source and victim.
This can be achieved by filtering, shielding and grounding.
Filtering
As mentioned above, high frequency energy can be coupled between
circuits via radiation or conduction. The AC power wiring is one of
the most important paths for both types of coupling mechanisms. The
AC line can conduct noise into the drive from other devices, or it can
conduct noise directly from the drive into other devices. It can also act
as an antenna and transmit or receive radiated noise between the drive
and other devices.
Figure E.1 EMI Source-Victim Model
Intro
EMI
VICTIM
EMI
SOURCE
EMI
VICTIM
CONDUCTED EMI
RADIATED
EMI