Safety; High Voltage Test; Safety Earth Connection; Emc-Correct Installation - Danfoss VLT Design Manual

How to Install
5.5.3 MCT 31
The MCT 31 harmonic calculation PC tool enables easy
estimation of the harmonic distortion in a given
application. Both the harmonic distortion of Danfoss
frequency converters as well as non-Danfoss frequency
converters with different additional harmonic reduction
devices, such as Danfoss AHF filters and 12-18-pulse
rectifiers, can be calculated.
Ordering number:
Order your CD containing the MCT 31 PC tool, using code
number 130B1031.
MCT 31 can also be downloaded from the Danfoss
Internet: http://www.danfoss.com/BusinessAreas/DrivesSo-
lutions/Softwaredownload/.

5.6 Safety

5.6.1 High Voltage Test

Carry out a high voltage test by short-circuiting terminals
U, V, W, L , L and L . Energize maximum 2.15 kV DC for
1 2 3
380-500 V frequency converters and 2.525 kV DC for
525-600 V frequency converters for one second between
this short-circuit and the chassis.
WARNING
When running high voltage tests of the entire installation,
interrupt the mains and motor connection if the leakage
currents are too high.
Failure to follow recommendations could result in death or
serious injury.

5.6.2 Safety Earth Connection

The frequency converter has a high leakage current and
must be earthed appropriately for safety reasons according
to EN 50178.
WARNING
The earth leakage current from the frequency converter
exceeds 3.5 mA. To ensure a good mechanical connection
from the earth cable to the earth connection (terminal 95),
the cable cross-section must be at least 10 mm
earth wires terminated separately.
®
VLT Refrigeration Drive Design Guide

5.7 EMC-correct Installation

5.7.1 Electrical Installation - EMC
The following is a guideline to good engineering practice
when installing frequency converters. Follow these
guidelines to comply with EN 61800-3 First environment. If
the installation is in EN 61800-3 Second environment, i.e.
industrial networks, or in an installation with its own
transformer, deviation from these guidelines is allowed but
not recommended. See also , 2.9.1 General Aspects of EMC
Emissions and .
Good engineering practice to ensure EMC-correct
electrical installation:
2
or 2 rated
Leave the screen as close to the connectors as possible.
Illustration 5.31 shows an example of an EMC-correct
electrical installation of an IP20 frequency converter. The
frequency converter is fitted in an installation cabinet with
an output contactor and connected to a PLC, which is
®
MG16G102 - VLT is a registered Danfoss trademark
Precautions
•
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. If so, connect
the screen at the frequency converter. See also
5.7.3 Earthing of Screened/Armoured Control
Cables .
•
Avoid terminating the screen/armour with twisted
ends (pigtails). It 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.
•
Avoid using unscreened/unarmoured motor or
control cables inside cabinets housing the
drive(s), whenever this can be avoided.
5 5
77