Danfoss VLT Series Design Manual page 118

5. How to Install
5.7. EMC-correct Installation
5.7.1. Electrical Installation -
The following is a guideline for good engineering practice when installing adjustable frequency
drives. Follow these guidelines to comply with EN 61800-3 First environment. If the installation is
5
in EN 61800-3
transformer, deviation from these guidelines is allowed but not recommended. See also para-
graphs
Good engineering practice to ensure EMC-correct electrical installation:
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Leave the shield as close to the connectors as possible.
The illustration shows an example of an EMC-correct electrical installation of an IP 20 adjustable
frequency drive. The adjustable frequency drive is fitted in an installation cabinet with an output
contactor, and connected to a PLC installed in a separate cabinet. Other ways of performing the
installation may result in an equally effective EMC performance, provided the above guidelines for
engineering practice are followed.
If the installation is not carried out according to the guidelines, and if non-shielded cables and
control wires are used, some emission requirements will not be fulfilled, although the immunity
requirements will be. See the paragraph
118
The ground leakage current from the adjustable frequency drive exceeds 3.5 mA.
To ensure a good mechanical connection from the ground cable to the ground con-
nection (terminal 95), the cable cross-section must be at least 0.39 in2 [10 mm2]
or 2 rated ground wires terminated separately.
Second environment
CE Labeling, General Aspects of EMC Emission
Use only braided shielded/armored motor cables and braided shielded/armored control
cables. The shield should provide a minimum coverage of 80%. The shield material must
be metal, not limited to, but typically, copper, aluminum, steel or lead. There are no
special requirements for the line cable.
Installations using rigid metal conduits are not required to contain shielded cable, but
the motor cable must be installed in conduit separate from the control and line cables.
Full connection of the conduit from the drive to the motor is required. The EMC per-
formance of flexible conduits varies greatly, and information from the manufacturer must
therefore be obtained.
Connect the shield/armor/conduit to ground at both ends for motor cables as well as for
control cables. In some cases, it is not possible to connect the shield at both ends. If so,
connect the shield at the adjustable frequency drive. See also
Shielded/Armored Control Cables
Avoid terminating the shield/armor with twisted ends (pigtails). It increases the high
frequency impedance of the shield, which reduces its effectiveness at high frequencies.
Use low-impedance cable clamps or EMC cable glands instead.
Avoid using unshielded/unarmored motor or control cables inside cabinets housing the
drive(s), whenever this can be avoided.
MG.11.B4.22 - VLT
, i.e., industrial networks, or in an installation with its own
EMC Test Results
and
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EMC test results
.
® is a registered Danfoss trademark.
VLT ® HVAC Drive Design Guide
.
Grounding of Braided