Electromagnetic Coupling (Radiative Coupling); Emc-Compliant Installation - Siemens SINAMICS G130 Engineering Manual

EMC Installation Guideline
Engineering Information
The diagram below shows an electrical circuit fed by a source of interference. This circuit induces an interference
voltage V into a signal circuit by means of a magnetic interference field B
I
interference current I , which generates a voltage drop at impedance Z
I
can result in a fault.
Inductive coupling of an interference voltage into a signal circuit
If, for example, the source of interference is a braking chopper (i.e. a Braking Module) connected to the converter DC
link, then a high, pulsating current flows to the connected braking resistor during braking operation. Due to its
magnitude and its high current rate-of-rise di/dt, this pulsating current induces a pulsating interference voltage in the
signal circuit, which results in an pulsating interference current. If this interference current flows, for example, via the
digital inputs into the converter interface module malfunctions can occur (e.g. sporadic fault tripping).
Measures for reducing inductive coupling
·
Maximize the distance between the conductors / conductor loops
·
Keep the area of each conductor loop as small as possible: route the feed and return lines of each circuit in
parallel so that they are lying as close to each other as possible, or use twisted cables for the signal cable.
·
Use shielded signal cables (in the case of inductive coupling, shield bonding must be ensured at both ends).

2.3.4.1.4 Electromagnetic coupling (radiative coupling)

Electromagnetic or radiative coupling is an interference by means of a radiated electromagnetic field. Typical sources
of this kinf of interference are:
·
Cellular radio devices
·
Cellular phones
·
Devices that operate using spark gaps
(Spark plugs, welding devices, contactors and switches when switching contacts are opened)
Methods for reducing electromagnetic coupling
As the electromagnetic fields are in the high-frequency range, the shielding measures provided below for reducing
radiative interference must be implemented in such a way that they are effective even at highest frequencies:
·
Use metallic converter cabinets in which individual components (cabinet frame, walls, doors, etc.) are
connected to each other with excellent electrical conductivity.
·
Use metallic housings for devices and electronic boards, which are connected to each other and to the
cabinet frame with excellent electrical conductivity.
·
Use shielded cables with finely stranded, braided shields suitable for high frequencies.

2.4 EMC-compliant installation

The previous section covered the basic principles of EMC of the frequency converter. It covered interference sources
and potentially susceptible equipment, the various coupling principles, as well as basic measures for reducing
interference.
Based on this, the next section covers all of the most important rules for ensuring that converter cabinets are
constructed and drive systems are installed in accordance with the EMC requirements.
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. The interference voltage V
I
of the potentially susceptible equipment, which
i
creates an
I