Grounding; Extra Protection (Rcd); Rfi Switch; Torque - Danfoss VLT AQUA FC 202 Operating Instructions Manual

How to Install

3.6.2 Grounding

The following basic issues need to be considered when
installing a frequency converter, so as to obtain electro-
magnetic compatibility (EMC).
•
Safety grounding: The frequency converter has a
high leakage current and must be grounded
appropriately for safety reasons. Apply local
safety regulations.
•
High-frequency grounding: Keep the ground wire
connections as short as possible.
Connect the different ground systems at the lowest
possible conductor impedance. The lowest possible
conductor impedance is obtained by keeping the
conductor as short as possible and by using the greatest
possible surface area.
The metal cabinets of the different devices are mounted
on the cabinet rear plate using the lowest possible HF
impedance. This avoids having different HF voltages for
the individual devices and avoids the risk of radio
interference currents running in connection cables that
may be used between the devices. The radio interference
has been reduced.
To obtain a low HF impedance, use the fastening bolts of
the devices as HF connection to the rear plate. It is
necessary to remove insulating paint or similar from the
fastening points.

3.6.3 Extra Protection (RCD)

ELCB relays, multiple protective earthing or earthing can
be used as extra protection, provided that local safety
regulations are complied with.
In case of an ground fault, a DC component may develop
in the fault current.
If ELCB relays are used, local regulations must be observed.
Relays must be suitable for protection of 3-phase
equipment with a bridge rectifier and for a brief discharge
on power-up.
See also Special Conditions in the Design Guide.

3.6.4 RFI Switch

Mains supply isolated from earth
If the frequency converter is supplied from an isolated
mains source ( IT mains, floating delta and grounded delta)
or TT/TN-S mains with grounded leg, the RFI switch is
recommended to be turned off (OFF) via 14-50 RFI Filter on
the frequency converter and 14-50 RFI Filter on the filter.
For further reference, see IEC 364-3. In case optimum EMC
performance is needed, parallel motors are connected or
the motor cable length is above 25 m, it is recommended
to set 14-50 RFI Filter to [ON].
VLT AQUA Drive FC 202 Operation Instructions
In OFF, the internal RFI capacities (filter capacitors)
between the chassis and the intermediate circuit are cut
off to avoid damage to the intermediate circuit and to
reduce the earth capacity currents (according to IEC
61800-3).
Also refer to the application note VLT on IT Mains It is
important to use isolation monitors that are capable for
use together with power electronics (IEC 61557-8).

3.6.5 Torque

When tightening all electrical connections it is very
important to tighten with the correct torque. Too low or
too high torque results in a bad electrical connection. Use
a torque wrench to ensure correct torque.
Nm/in-lbs
Illustration 3.68 Tightening Bolts with a Torque Wrench
Enclosure
types
D
E
MG20P402 - Rev. 2013-12-16
Terminal Torque [Nm] (in-lbs) Bolt size
Mains 19-40
Motor (168-354)
Load sharing 8.5-20.5
Brake (75-181)
Mains
19-40
Motor
(168-354)
Load sharing
Brake 8.5-20.5
(75-181)
3 3
M10
M8
M10
M8
53