General Information About Electrical Installation; Earthing; Extra Protection; High Voltage Warning - Danfoss VLT 2800 Series Operating Instructions Manual

General information about electrical installation

High voltage warning

The voltage of the frequency converter
is dangerous whenever the equipment is
connected to mains.Incorrect fitting of the
motor or frequency converter may cause damage to
the equipment, serious injury or death. Conse-
quently, the instructions in this manual, as well as
national and local rules and safety regulations must
be complied with.
Touching the electrical parts may be fatal
- even after the equipment has been disconnected
from mains: Wait at least 4 minutes.
NB!:
It is the user's or fitter's responsibility to
ensure correct earthing and protection in ac-
cordance with national and local standards.

Earthing

The following basic points must be considered at in-
stallation:
• Safety earthing: Please note that the frequency
converter has a high leakage current and must
be earthed appropriately for safety reasons. Ap-
ply local safety regulations.
• High frequency earthing: Keep earthing connec-
tions as short as possible.
Connect the different earthing systems, thereby en-
suring the lowest possible conductor impedance.
The lowest possible conductor impedance is
achieved by keeping the conductor as short as pos-
sible and by using the greatest possible surface
area. A flat conductor, for example, has a lower HF-
impedance than a round conductor, calculated for
the same conductor cross-section C
units are installed in cabinets, the cabinet backplate,
which must be made of metal, should be used as a
joint earth reference plate. The metal cabinets of the
different units must be fitted to the cabinet backplate
at the lowest possible HF-impedance. With this fea-
ture, different HF-voltages will not arise in different
units, and there will be no noise currents in cables
used to connect units. Noise radiation will be re-
duced. In order to achieve a low HF-impedance, the
fastening bolts of the units can be used as HF-
connection to the backplate. It is necessary to
remove any layers of isolating paint or similar from
the attachment points.
MG.28.A5.02 - VLT is a registered Danfoss trade mark
VLT

Extra protection

RCD relays, multiple protective earthing or earthing
can be used as extra protection, provided that local
safety regulations are complied with. In the case of
an earth fault, a DC content may develop in the faulty
current. Never use an RCD (ELCB relay), type A, as
it is not suitable for DC faulty currents. If RCD relays
are used, local regulations must be complied with.
If RCD relays are used, they must be:
- Suitable for protecting equipment with a DC con-
tent in the faulty current (3-phase bridge rectifier)
- Suitable for a pulse-shaped, brief discharge on
power-up
- Suitable for a high leakage current.
High voltage test
A high voltage test can be performed by short-
circuiting terminals U, V, W, L1, L2 and L3, and
applying max. 2160 V DC in 1 sec. between this
short-circuit and terminal 95.
. If several
VESS
®
2800 Series
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