Input Options; Extra Protection (Rcd); Rfi Switch; Shielded Cables - Danfoss VLT AutomationDrive FC 302 Installation Manual

Electrical Installation
Connect the different ground systems at the lowest
possible conductor impedance. Keep the conductor as
short as possible and use the greatest possible surface
area for the lowest possible conductor impedance.
The metal cabinets of the different devices are mounted
on the cabinet rear plate using the lowest possible HF
impedance. Doing so avoids different HF voltages for
4 4
individual devices and the risk of radio interference
currents running in connection cables between the
devices. The radio interference is reduced.
To obtain a low HF impedance, use the fastening bolts of
the devices as HF connection to the rear plate. Remove
insulating paint or similar from the fastening points.
4.4.1 Leakage Current (>3.5 mA)
Follow national and local codes regarding protective
earthing of equipment with a leakage current >3.5 mA.
Frequency converter technology implies high frequency
switching at high power. This generates a leakage current
in the ground connection. A fault current in the frequency
converter at the output power terminals might contain a
DC component, which can charge the filter capacitors and
cause a transient ground current. The earth leakage
current depends on various system configurations
including RFI filtering, screened motor cables, and
frequency converter power.
EN/IEC61800-5-1 (Power Drive System Product Standard)
requires special care if the leakage current exceeds 3.5 mA.
Grounding must be reinforced in 1 of the following ways:
•
Ground wire of at least 10 mm
•
2 separate ground wires both complying with the
dimensioning rules.
See EN 60364-5-54 § 543.7 for further information.

4.5 Input Options

4.5.1 Extra Protection (RCD)

ELCB relays, multiple protective grounding, or standard
grounding provide extra protection, if local safety
regulations are followed.
In the case of a ground fault, a DC component develops in
the fault current.
If using ELCB relays, observe local regulations. Relays must
be suitable for protection of 3-phase equipment with a
bridge rectifier and for a brief discharge on power-up.
38
®
VLT AutomationDrive FC 302 Low Harmonic Drive
132–630 kW

4.5.2 RFI Switch

Line power supply isolated from ground
If the adjustable frequency drive is supplied from an
isolated line power source or TT/TN-S line power with
grounded leg, turn off the RFI switch via
parameter 14-50 RFI 1 on both adjustable frequency drive
and the filter. For further reference, see IEC 364-3. When
optimum EMC performance is needed, parallel motors are
connected, or the motor cable length is above 82 ft [25
m], set parameter 14-50 RFI 1 to [ON].
In OFF, the internal RFI capacitors (filter capacitors)
between the chassis and the intermediate circuit are cut
off to avoid damage to the intermediate circuit and reduce
ground capacity currents (IEC 61800-3).
Refer to the application note VLT on IT line power. It is
important to use isolation monitors that work together
with power electronics (IEC 61557-8).

4.5.3 Shielded Cables

It is important to connect shielded cables properly to
ensure high EMC immunity and low emissions.
Connection can be made using either cable connectors
or clamps:
2
.

4.6 Motor Connection

4.6.1 Motor Cable

Connect the motor to terminals U/T1/96, V/T2/97, W/T3/98,
on the far right of the unit. Ground to terminal 99. All
types of 3-phase asynchronous standard motors can be
used with an adjustable frequency drive. The factory
setting is for clockwise rotation with the adjustable
frequency drive output connected as follows:
Terminal No.
96, 97, 98, 99
Table 4.2 Terminal Functions
Danfoss A/S © Rev. 04/2015 All rights reserved.
•
EMC cable connectors: generally available cable
connectors can be used to ensure an optimum
EMC connection.
•
EMC cable clamp: Clamps allowing easy
connection are supplied with the unit.
Function
Line power U/T1, V/T2, W/T3
Ground
•
Terminal U/T1/96 connected to U-phase
•
Terminal V/T2/97 connected to V-phase
•
Terminal W/T3/98 connected to W-phase
MG37A322