Rockwell Automation 1336T FORCE Series B - Manual (Page 33)

Chapter 2
Installation/Wiring
2–13
Electrical Interference – EMI/RFI Immunity
The immunity of 1336 FORCE drives to externally generated interference
is good. Usually, no special precautions are required beyond the installation
practices provided in this publication.
It is recommended that the coils of DC energized contactors associated
with drives be suppressed with a diode or similar device, since they can
generate severe electrical transients.
In areas subject to frequent lightning strikes, additional surge suppression
is advisable. Suitable MOVs connected between each line and ground
should be used (see Figure 2–8).
Emission
Careful attention must be given to the arrangement of power and ground
connections to the drive to avoid interference with nearby sensitive
equipment. Refer to “Motor Cables” Appendix A. The cable to the motor
carries switched voltages and should be routed well away from sensitive
equipment.
The ground conductor of the motor cable should be connected to the drive
ground (PE) terminal directly. Connecting this ground conductor to a
cabinet ground point or ground bus bar may cause high frequency current
to circulate in the ground system of the enclosure. The motor end of this
ground conductor must be solidly connected to the motor case ground.
Shielded or armored cable may be used to guard against radiated emissions
from the motor cable. The shield or armor should be connected to the drive
ground terminal (PE) and the motor ground as outlined above.
Common mode chokes are recommended at the drive output to reduce the
common mode noise.
An RFI filter can be used and in most situations provides an effective
reduction of RFI emissions that may be conducted into the main supply
lines.
If the installation combines a drive with sensitive devices or circuits, it is
recommended that the lowest possible drive PWM frequency be
programmed.