User Manual V 1-4.XX User guide

2-28 Mounting and Wiring Your 1336 IMPACT Drive
Electrical Interference —
EMI/RFI
Immunity
The immunity of 1336 IMPACT drives to externally generated
interference is good. Usually, no special precautions are required
beyond the installation practices provided in this manual.
You should suppress the coils of DC energized contactors associated
with drives with a diode or similar device, because they can generate
severe electrical transients.
In areas subject to frequent lightning strikes, additional surge
suppression is advisable. You should use suitable MOVs connected
between each line and ground. Refer to Figure 2.7 for additional
information about MOVs.
Emission
To avoid interference with nearby sensitive equipment, you must be
careful about how you arrange the power and ground connections to
the drive. Route the cable that goes to the motor well away from
sensitive equipment, as the motor cable does carry switched voltages.
Connect the ground conductor of the motor cable 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. You must solidly
connect the motor end of this ground conductor to the motor case
ground.
You may use shielded or armored cable to guard against radiated
emissions from the motor cable. Connect the shield or armor to the
drive chassis.
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,
program the lowest possible drive PWM frequency.
Do I Need an RFI Filter? You can install 1336 IMPACT drives with an RFI filter. The RFI filter
controls radio-frequency conducted emissions into the main supply
lines and ground wiring. If you follow the cabling and installation
instructions described in this manual, interference problems are
unlikely when the drive is used with conventional industrial electronic
circuits and systems.
You should use the optional RFI filter if:
• You must conform to a standard such as EN 55011, VDE0875,
BSI, or FCC.
• You need to achieve very low emission levels.
• You are installing sensitive devices or circuits on the same AC
supply.
• The motor cable exceeds 50 meters (164 feet). Beyond this
length, capacitance to ground increases the supply emissions.