Rockwell Automation SA3100 AC Power Modules - Manual (Page 42)

3-24 SA3100 Power Modules
3.15 Controlling Power Module Emissions
Careful attention must be given to the arrangement of power and ground connections
to the Power Module in order to avoid interference with nearby sensitive equipment.
The cable to the motor carries switched voltages and should be routed away from
sensitive equipment. The ground conductor of the motor cable should be connected
to the Power Module 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 Power Module ground
terminal (PE) and the motor case ground.
Common mode chokes are recommended at the Power Module output to reduce the
common mode currents.
If the installation combines a Power Module with sensitive devices or circuits, it is
recommended that the lowest possible Power Module PWM frequency be
programmed.
3.15.1 Installing the Optional RFI Filter
If the cabling and installation recommendations given in this manual are followed, it is
unlikely that radio-frequency interference problems will occur when the Power Module
is used with conventional industrial electronic circuits and systems. The optional RFI
filter is recommended, however, if sensitive devices or circuits are installed on the
same AC supply or if the motor cable exceeds 50 meters (164 feet). Beyond this
length, the capacitance to ground will increase the supply emissions.
The RFI filter should also be used if very low emission levels are essential or if
conformity with standards (EN 55011, VDE0875, BSA, FCC, etc.) is required.
Important: Conformity of the Power Module and filter to any standard does not
ensure that the entire installation will conform, since many other factors
can affect the installation. Only direct measurements can verify total
conformity.
The RFI filter is connected between the incoming AC supply line and the Power
Module’s AC input terminals. The filter should be installed physically close to the
Power Module, on the same mounting plate if possible, using short connections. To
ensure that the RFI filter is effective, the motor cable must be shielded or armored and
the guidelines in this manual must be followed.