High Voltage Test; Safety Earthing; Electrical Installation - Emc Precautions - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide

High Voltage Test

"
Carry out a high voltage test by short-circuiting terminals U, V, W, L
2.15 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 connection if the leakage currents are too high.

Safety Earthing

"
The frequency converter has a high leakage current and must be earthed appropriately for safety reasons.
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 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 Earthing of Braided 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.
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 converter.
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.
I 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.
How to Install
MG.33.B4.02 - VLT is a registered Danfoss trademark
, L and L . Energize by max.
1 2 3
105