2 Engineering
2.4 EMC measures
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DE1 variable speed starter
09/14 MN040011EN
www.eaton.com
2.4 EMC measures
When designing drives systems with variable speed (PDS), the necessary
electromagnetic compatibility (EMC) measures should already be taken into
account during the planning and configuration stage, as making changes
during assembly and installation (or afterwards) at the installation location will
likely result in additional, and significantly higher, costs.
Due to the characteristics of the technology and systems involved, high-
frequency leakage currents will flow in a frequency controlled drive system
during operation. Because of this, all earthing elements must be low-
impedance elements connected in such a way as to establish an electrical
contact across a large surface area.
We recommend the following in order to ensure that DE1 variable speed
starters are installed in a manner that meets EMC requirements:
•
Install the variable speed starter(s) in a conductive metal enclosure with
a good connection to earth potential
•
Screened cables with the shortest possible length
Inside the control panel, all of the device's metal parts should be connected
to each other and to the control panel across a large area and in a manner
suitable for high frequencies. Mounting plates and control panel doors should
be connected to the panel by means of short drain wires with an electrical
contact established across a large surface area.
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When working with frequency controlled drive systems,
connect all conductive components, as well as the enclosure, to
earth using a cable that is as short as possible and that has the
largest possible cross-sectional area (copper lacing).
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Mount the DE1 variable speed starter as directly as possible
(without spacers) on a metal plate (mounting plate).
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Route mains and motor cables in the control panel as close to
the ground potential as possible. This is because free moving
cables act as antennas.
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If routed in parallel, cables carrying high frequencies
(e.g., screened motor cables) and clean cables (e.g., mains
supply cable, control and signal cables) should be installed at a
distance of at least 300 mm from each other in order to avoid
electromagnetic interference.
You should also route cables separately from each other if there
are large differences in voltage. If control cables and power
cables need to cross, they should always do so at a right angle
(90°).