Siemens Simovert Masterdrives Compendium page 95

Instructions for Design of Drives in Conformance with EMC Regulations
3.4 EMC planning
3-8
In the case of analog signal cables, low-frequency noise can arise if
the shield is connected at both ends (hum is coupled-in). In this case,
the shield must only be connected at one end at the SIMOVERT
MASTERDRIVES. The other end of the shield should be grounded
through a capacitor (e.g. 10 nF/100 V type MKT). This capacitor
enables the shield to be connected at both ends after all as far as high-
frequency noise is concerned.
If two units are not electromagnetically compatible, the noise radiated
by the noise transmitter can be reduced, or the noise immunity of the
noise receiver can be increased. Noise sources are often power
electronic units with a large current drain. Complex filters are necessary
to reduce their noise emission. Noise receivers especially include
control devices and sensors/transmitters, as well as their evaluation
circuit. Not so much effort and cost is required to increase the noise
immunity of low-power units. In industrial environments, it is therefore
more cost-effective to increase the noise immunity than to reduce the
noise emission.
To maintain the "Second environment" limit value class specified in EN
55011, the radio interference voltage at the mains connection point can
be a maximum of 79 dB (µV) between 150 kHz and 500 kHz, and a
maximum of 73 dB (µV) between 500 kHz und 30 MHz. When
expressed in volts, these values are 9 mV and 4.5 mV respectively!
Before radio interference measures can be applied, it must first be
clarified at which locations you or your customer require EMC. See the
following example:
6SE7087-6QX70 (Version AD)
Compendium Motion Control
05.2003
Siemens AG
SIMOVERT MASTERDRIVES