Rockwell Automation 160-DN2 160-DN2 DeviceNet Communication Module FRN 3.xx - Manual (Page 20)

Publication 0160-5.18 - June 2003
3-4 Installation and Wiring
Common Mode Noise To greatly reduce high frequency common mode noise current
coupled to ground in high capacitance connections, connect a
common mode choke at the drive end of the motor cable. The
common mode choke reduces the rise time of the high frequency
noise by a factor of 10-20, and the amplitude by a factor of 5. For
multiple 460 volt drive installations with sensitive equipment (e.g.
PLC’s, temperature sensors, sonar detectors, strain gauges, etc.)
sharing a common ground separated by more than 30 feet, you must
install common mode chokes at the outputs of each drive.
In addition to greatly reducing high frequency common mode noise
induced by the drive, a common mode choke also effectively reduces
high frequency common mode noise that is induced by regularly
cycled inductive loads. In installations where inductively-coupled
common mode noise causes system problems, connect a common
mode choke at the source of the inductively-switched load.
For drives on a DeviceNet network, we highly recommend connecting
a common mode choke at the drive end of the motor cable.
Drive Output Disconnect The drive is intended to be commanded by control signals that will
start and stop the motor. Do not use a device that routinely connects
or disconnects output power to the motor with the drive outputting
power (for the purpose of starting and stopping the motor, or for
machine positioning). Connecting or disconnecting power to the
motor with the drive outputting power can produce transient EMI
which can cause network problems to occur.
For emergency stop conditions, make sure that terminal 7 and 8 on
TB2 is broken (opened) using an auxiliary contact of a motor output
contactor. Also, remember to set the Stop Select parameter to “Coast
to Stop.”