Danfoss VLT AutomationDrive FC 300 Design Manual page 104

FC 300 Design Guide
High Voltage Test
Carry out a high voltage test by short-circuiting terminals U, V, W, L
kV DC for one second between this short-circuit and the chassis.
NB!
When running high voltage tests of the entire installation, interrupt the mains and motor con-
nection if the leakage currents are too high.
Safety Earth Connection
The frequency converter has a high leakage current and must be earthed appropriately for safety reasons
acording to EN 50178.
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 mm2 or 2 rated earth wires terminated separately.
Electrical Installation - EMC Precautions
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 paragraphs CE Labelling, General Aspects of EMC
Emission and EMC Test Results.
Good engineering practice to ensure EMC-correct electrical installation:
• Use only braided screened/armoured motor cables and braided screened/armoured control ca-
bles. 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 Earthing of Braided Screened/Armoured Control Ca-
bles.
• 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.
Leave the screen as close to the connectors as possible.
The illustration shows an example of an EMC-correct electrical installation of an IP 20 frequency con-
verter. The frequency converter is fitted in an installation cabinet with an output contactor and connected
to a PLC, which is installed in a separate cabinet. Other ways of doing the installation may have just as
good an EMC performance, provided the above guide lines to engineering practice are followed.
If the installation is not carried out according to the guideline and if unscreened cables and control wires
are used, some emission requirements are not complied with, although the immunity requirements are
fulfilled. See the paragraph EMC test results.
104
How to Install
MG.33.B8.02 - VLT ® is a registered Danfoss trademark
, L and L . Energize by max. 2.15
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