General Information About Electrical Installation - Danfoss VT2800 Series Design Manual

High voltage warning
The voltage of the frequency converter
is dangerous whenever the equipment is
connected to mains. Incorrect installation
of the motor or frequency converter may cause
damage to the equipment, serious injury or death.
Comply with the instructions in this manual, as well as
national and local rules and safety regulations.
Touching the electrical parts may be fatal - even after
the equipment has been disconnected from mains:
Wait at least 4 minutes for current dissipate.
NB!:
It is the responsibility of the user or installer
to ensure correct earthing and protection in
accordance with national and local standards.
Earthing
Comply with the following at installation:
• Safety earthing: The dri v e has a high leakage
current and must be earthed properly for safety.
Follow all local safety regulations.
• High frequency earthing: Keep earthing
connections as short as possible.
Connect all earthing systems to ensure the lowest
possible conductor impedance. The lowest possible
conductor impedance is achieved by keeping the
conductor as short as possible and by grounding with
the greatest possible surface area. If multiple dri v es
are installed in a cabinet, the cabinet backplate, which
must be made of metal, should be used as a joint
earth reference plate. The dri v es must be fitted to the
backplate at the lowest possible impedance.
To achieve low impedance, connect the dri v e to the
backplate with the dri v e fastening bolts. Remove
all paint from the contact points.
Cables
The control cable and the mains cable should be
installed separately from motor cables to prevent
noise transfer. As a rule a distance of 20 cm is
sufficient, but it is recommended that the distance
is as great as possible, particularly when cables are
installed in parallel over large distances.
For sensiti v e signal cables such as telephone or data
cables the greatest possible distance is recommended.
Please note that the required distance depends on the
installation and the sensiti v ity of the signal cables, and
that for this reason exact values cannot be gi v en.
MG.28.E9.02 - VLT is a registered Danfoss trademark
®
VLT 2800 Series
When being placed in cable trays, sensiti v e cables
may not be placed in the same cable tray as the
motor cable. If signal cables run across power
cables, this is done at an angle of 90 degrees.
Remember that all noise-filled inlet and outlet cables
to a cabinet must be screened/armoured.
See also EMC-compliant electrical installation.
Screened/armoured cables
The screen must have low HF impedance, which is
achieved by a braided screen of copper, aluminium or
iron. Screen reinforcement intended for mechanical
protection, for example, is not suitable for EMC-correct
installation. See also Use of EMC-correct cables.
Extra protection
RCD relays, multiple protecti v e 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 content
in the faulty current (3-phase bridge rectifier).
- Suitable for a pulse-shaped, brief discharge
on power-up.
- Suitable for a high leakage current.
N must be connected before L1 for single phase 200
V reduced leakage current units (type code R4).
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.
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