Simoreg Converters In Industrial Applications; Non-Grounded Supply Systems; Emc Planning - Siemens 6RA7086-6KS22 Operating Instructions Manual

05.05
Noise immunity defines the behaviour of a piece of equipment when subjected to electromagnetic
disturbance. The Product Standard regulates the requirements and assessment criteria for the
behaviour of equipment in industrial environments. The converters in this description comply with
this Standard (Section 6.1.2.3).
6.1.1.4

SIMOREG converters in industrial applications

In an industrial environment, equipment must have a high level of noise immunity whereas lower
demands are placed on noise radiation.
SIMOREG DC Master converters are components of an electrical drive system in the same way as
contactors and switches. Properly qualified personnel must integrate them into a drive system
consisting, at least, of the converter, motor cables and motor. Commutating reactors and fuses are
also required in most cases. Limit values can only be maintained if these components are installed
and mounted in the correct way. In order to limit the radiated noise according to limit value "A1",
the appropriate radio interference suppression filter and a commutating reactor are required in
addition to the converter itself. Without an RI suppression filter, the noise radiated by a SIMOREG
DC Master converters exceeds limit value "A1" as defined by EN55011.
If the drive forms part of a complete installation, it does not initially have to fulfil any requirements
regarding radiated noise. However, EMC legislation requires the installation as a whole to be
electromagnetically compatible with its environment.
If all control components in the installation (e.g. PLCs) have noise immunity for industrial
environments, it is not necessary for each drive to meet limit value "A1" in its own right.
6.1.1.5

Non-grounded supply systems

Non-grounded supply systems (IT systems) are used in a number of industrial sectors in order to
increase plant availability. In the event of a ground fault, no fault current flows so that the plant can
still produce. When RI suppression filters are installed, however, a ground fault does cause a fault
current to flow, resulting in shutdown of the drives and, in some cases, destruction of the
suppression filter. For this reason, the Product Standard does not define limit values for these
supply systems. From the economic viewpoint, RI suppression should, if required, be implemented
on the grounded primary side of the supply transformer.
6.1.1.6

EMC planning

If two units are not electromagnetically compatible, you can either reduce the noise radiated by the
noise source, or increase the noise immunity of the noise receiver. Noise sources are generally
power electronics units with a high power consumption. To reduce the radiated noise from these
units, complex, costly filters are required. Noise receivers are predominantly control equipment and
sensors including evaluation circuitry. Increasing the noise immunity of less powerful equipment is
generally easier and cheaper. In an industrial environment, therefore, it is often more cost-effective
to increase noise immunity rather than reduce radiated noise. For example, in order to adhere to
limit value class A1 of EN 55011, the noise suppression voltage at the mains connection may be
max. 79 dB(µV) between 150 kHz and 500 kHz and max. 73 dB (µV) (9 mV or 4.5 mV) between
500 kHz and 30 MHz.
In industrial environments, the EMC of the equipment used must be based on a well-balanced
mixture of noise radiation and noise immunity.
The most cost-effective RI suppression measure is the physical separation of noise sources and
noise receivers, assuming that it has already been taken into account when designing the
machine/plant. The first step is to define whether each unit is a potential noise source (noise
radiator or noise receiver). Noise sources are, for example, PLCs, transmitters and sensors.
Components in the control cabinet (noise sources and receivers) must be physically separated, if
necessary through the use of metal partitions or metal enclosures for individual components.
Figure 1 shows an example component layout in a control cabinet.
Siemens AG 6RX1700-0AD76
SIMOREG DC Master Operating Instructions
Connections
6-3