20
VLT
®
3500 HVAC
MG.35.B1.02 – VLT is a registered Danfoss trademark
Filtering
Electrical interference from the cable network - cable-
borne as well as air-borne - can be prevented by
using the correct filters. The filters or equivalent stated
in the product programme must be installed, and
when remounting, the filter installation instructions are
to be observed.
VLT 3502-3562
All models are available with or without an integrated
RFI filter. Also, RFI filters can be purchased as a sepa-
rate module/option. See product range.
VLT 3575-3800 and 3542-3562 (230 V)
RFI filters are available in a separate IP54 enclosure or
in an IP20 version for separate installation.
Special installation guidelines must be complied with.
Mechanical installation
VLT 3502 - VLT 3511, IP00/21 enclosure without
integrated RFI filter must always be installed against a
conductive rear plate.
Install the metal cabinet of the VLT frequency converter
up against the rear plate. The rear plate must be
electrically conductive and act as a common HF earth
reference for the VLT frequency converter and the RFI/
module. The VLT frequency converter and the RFI/
module must be installed with the lowest possible HF
impedance to the rear plate. This can best be done
through the fastening bolts for the enclosure. Since the
aluminium enclosure of the VLT 3500 HVAC is anodised
and thus electrically insulating, toothed (serrated)
washers should be used to penetrate the anodisation -
or the anodised surface has to be removed. Remember
also to remove any varnish or paint from the rear plate.
VLT 3502-11, IP00/21 enclosure with RFI filter
VLT 3502-11, IP54 enclosure and VLT 3616-62, IP20/IP54
These VLT 3500 HVAC can be installed on an electrically
conductive or a non-conductive rear plate, since the RFI
filter is integrated and the screen from control cables and
motor cable can be terminated in the VLT frequency
converter.
If an electrically conductive rear plate is used, the VLT
frequency converter must be installed with the lowest
possible HF impedance to the rear plate, and the
instructions for installation must be complied with.
RFI filter/IP20 for VLT 3575-3800 and 3542-3562 (230 V)
•
The filter should be installed on the same panel as
the frequency converter. The panel must be
electrically conductive. Both the frequency converter
and the filter must have a good high-frequency
connection to the panel.
•
The filter should be connected as close as possible
to the frequency converter input, the maximum
EMC-correct installation instructions
2.6 E;MC-corr
ect installation
■
distance being 1 metre.
•
The mains filter should be earthed at both ends.
•
Before mounting the filter on the panel, remove any
surface treatment, etc.
RFI module IP54 for VLT 3575-3800 and 3542-3562
(230V)
1. Remove the access plate and the Philips screws in
the right-hand side of the VLT 3500 HVAC (save the
screws for the access plate for later use).
2. Place the IP54 RFI option on the right-hand side of
the VLT 3500 HVAC.
NB!
The filter must be earthed before connection
to mains.
Motor cable
In order to comply with the EMC specifications
concerning emission and immunity, the motor cable
must be screened unless otherwise stated for the
mains filter in question. It is important to keep the mo-
tor cable as short as possible so as to reduce the
interference level and the leakage currents to a mini-
mum.
The motor cable screen should be connected to the
metal cabinet of the frequency converter and to the
metal cabinet of the motor. Screen connections
should be made using as large a surface (cable
clamp, cable union) as possible. This has been
achieved by different installation devices in the
different VLT
frequency converters (see the
instructions for installation, pp.
pp.
pp.
pp.
pp. 21-22, item D).
Mounting with twisted screen ends (pigtails) should
be avoided, since this reduces the screening effect at
higher frequencies. The motor cable screen should
basically not be broken and not be earthed between
the motor and the drive. If it becomes necessary to
break the screen to install a motor guard or motor
relays, the screen should be continued past the relays
at the lowest possible HF impedance.