Rfi Switch; Direction Of Motor Rotation; Parallel Connection Of Motors - Danfoss VT2800 Series Design Manual

RFI switch

Mains supply isolated from earth:
If the frequency converter is supplied from an isolated
mains source ( IT mains) or TT/TN-S mains with
grounded leg, the RFI switch is recommended
to be turned off (OFF). 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 the switch in ON position.
In OFF position, 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).
Please also refer to the application note VLT on
IT mains, MN.90.CX.02. It is important to use
isolation monitors that are capable for use together
with power electronics (IEC 61557-8).
NB!:
The RFI switch is not to be operated with
mains connected to the unit. Check that
the mains supply has been disconnected
before operating the RFI switch.
NB!:
The RFI switch disconnects the capacitors
galvanically from ground.
The switch Mk9, placed next to terminal 96, should
be removed to disconnect the RFI-filter.
The RFI switch is only available on VLT 2880-2882.
MG.28.E9.02 - VLT is a registered Danfoss trademark
®
VLT 2800 Series

Direction of motor rotation

The factory setting is for clockwise rotation
with the frequency converter transformer output
connected as follows:
Terminal 96 connected to U-phase.
Terminal 97 connected to V-phase.
Terminal 98 connected to W-phase.
The direction of rotation can be changed by switching
two phases on the motor terminals.

Parallel connection of motors

The frequency converter is able to control several
motors connected in parallel. If the motors are
to have different rpm values, use motors with
different rated rpm values. Motor rpm is changed
simultaneously, which means that the ratio between
the rated rpm values is maintained across the range.
The total current consumption of the motors is
not to exceed the maximum rated output current
I for the frequency converter.
INV
51