User Manual

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Siemens TX-I/O Engineering and installation guide CM110562en_13
Building Technologies Control panel 2019-05-15
5.3 EMC compliant control panel
Please refer also to Section 6.7, "EMC compliant wiring".
One of the purposes of the control panel is to reduce electromagnetic interference. This
depends on the internal and external electromagnetic interference (EMI) affecting the
control panel.
For example, an AC inverter in the same control panel may represent an internal
source of interference, while external interference may be caused by a radio transmitter
in the near vicinity.
Control panels act as the reference point (earth) for cable screens and housings. They
must be capable of isolating interference and short-circuiting interference voltages.
For an EMC compliant control panel, the following general rules must be observed:
• Internal walls should not be painted in the case of difficult EMC conditions
• Grids and rails must be conductive and must not be painted
• Screws must be fixed directly to the bare (conductive) surfaces of the control panel
• Copper straps must be used for connecting the earth mass to control-panel doors
(possibly with an additional connection to the normal protective earth).
When designing the control panel, equipment emitting high levels of interference must
be isolated from equipment susceptible to interference. Special attention must be paid
to the connections between these two categories of equipment.
• Install high-level sources of interference and interference-susceptible devices in
separate control panels
• Locate high-level interference sources outside the control panel. Ensure that no
safety requirements are infringed in this process.
• Separate the groups of equipment within the control panel by use of partitions.
• Cable screens must be bonded to the metal structure of the control panel where they
enter the control panel, and to the equipotential bonding system of the building.
• Screen terminals must be used for this purpose, and suitable connection points must
be provided in the control panel (see illustration on page 50).
Use of the screen for module supply, see section 10.5, page 80.
Introduction
General rules
Mechanical design of
control panel
Layout of equipment in
control panel
Screening
Exception