Danfoss VLT 5000 FLUX, Руководство по эксплуатации, Страница: 38 / 158

VLT
®
5000 FLUX
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Electrical installation - EMC precautions
The following is a guideline to good engineering
practice, when installing drives. Following these
guidelines is advised, where compliance with EN
61000-6-3, EN 61000-6-4, EN 55011 or EN 61800-3
First environment is required. If the installation is in EN
61800-3 Second environment, i.e. industrial networks
or in an installation that has its own transformer, it
is acceptable to deviate from these guidelines. It is
however not recommended. See also CE labelling,
Emission and EMC test results under special conditions
in the Design Guide for further details.
Good engineering practice to ensure EMC-correct
electrical installation:
• Use only braided screened/armoured motor cables
and braided screened/armoured control cables. The
screen should provide a minimum coverage of 80%.
The screen material must be metal, not limited to
but typically copper, aluminium, steel or lead. There
are no special requirements for the mains cable.
• Installations using rigid metal conduits are not
required to use screened cable, but the motor
cable must be installed in conduit separate from
the control and mains cables. Full connection
of the conduit from the drive to the motor is
required. The EMC performance of flexible
conduits varies a lot and information from the
manufacturer must be obtained.
• Connect the screen/armour/conduit to earth
at both ends for motor cables as well as for
control cables. In some cases, it is not possible
to connect the screen in both ends. In these
cases, it is important to connect the screen at the
frequency converter. See also Earthing of braided
screened/armoured control cables .
• Avoid terminating the screen/armour with
twisted ends (pigtails). Such a termination
increases the high frequency impedance of the
screen, which reduces its effectiveness at high
frequencies. Use low impedance cable clamps
or EMC cable glands instead.
• It is important to ensure good electrical contact
between the mounting plate on which the frequency
converter is installed and the metal chassis of the
frequency converter. This however does not apply
to IP54 units as they are designed for wall mounting
and VLT 5122-5500 380-500 V and VLT 5032-5052
200-240 V in IP20/NEMA 1 enclosure.
• Use starwashers and galvanically conductive
installation plates to secure good electrical
connections for IP00 and IP20 installations.
• Avoid using unscreened/unarmoured motor or
control cables inside cabinets housing the drive(s),
whenever this can be avoided.
• An uninterrupted high frequency connection
between the frequency converter and the motor
units is required for IP54 units.
The illustration shows an example of an EMC-correct
electrical installation of an IP 20 frequency converter;
the frequency converter has been fitted in an installation
cabinet with an output contactor and connected to a
PLC, which in this example is installed in a separate
cabinet. In IP 54 units and VLT 5032-5052, 200-240
V in IP20/IP21/NEMA 1 enclosure screened cables
are connected by using EMC conduits to ensure
proper EMC performance. See illustration. Other
ways of making the installation may have as good
an EMC performance, provided the above guide
lines to engineering practice are followed.
Please note, that when the installation is not carried
through according to the guideline as well as when
unscreened cables and control wires are used, some
emission requirements are not complied with, although
the immunity requirements are fulfilled. See the section
EMC test results in the Design Guide for further details.
MG.55.A6.02 - VLT is a registered Danfoss trademark
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