Rfi Filters; Output Filters - Grundfos CUE Series Installation And Operating Instructions Manual

6.7 RFI filters

To meet the EMC requirements, the CUE comes with the
following types of built-in radio frequency interference filter (RFI).
Voltage Typical shaft power P2
3 x 380-500 V 110-250 kW
3 x 525-690 V 110-250 kW
Description of RFI filter types
For use in domestic and industrial areas, connected
permanently to the mains supply. In domestic areas,
C2:
special care should be taken regarding EMC-correct
installation.
For use in industrial areas with own low-voltage
C3:
transformer.
RFI filter types are according to EN 61800-3.
6.7.1 Equipment of category C2
• In a domestic environment this product may cause radio
interference in which case supplementary mitigation measures
may be required.
6.7.2 Equipment of category C3
• This type of power drive system (PDS) is not intended to be
used on a low-voltage public network which supplies domestic
premises.
• Radio frequency interference is expected if used on such a
network.

6.8 Output filters

Output filters are used for reducing the voltage stress on the
motor windings and the stress on the motor insulation system as
well as for decreasing acoustic noise from the frequency
converter-driven motor.
Two types of output filter are available as accessories for the
CUE:
• dU/dt filters
• sine-wave filters.
Use of output filters
Typical shaft
Pump type
power P2
SP, BM, BMB with
110 kW and up
380 V motor and up
Other pumps, noise
110 kW and up
reduction
Other pumps, higher
110 kW and up
noise reduction
Pumps with 690 V
motor
The lengths stated apply to the motor cable.
12
RFI filter type
C2
C3
dU/dt Sine-wave
filter filter
0-150 m 150-300 m
0-150 m 150-300 m
– 0-300 m
All – 0-300 m
Figures 30 and 31 show installations with and without filter and
where to use screened and unscreened cable.
Unscreened cable
CUE
Fig. 30 Example of installation without filter
Unscreened cable
CUE
Fig. 31 Example of installation with filter. The cable between
the CUE and filter must be short.
CUE and filter close to well
Screened
Unscreened
cable
cable
CUE
Fig. 32 Submersible pump without connection box
Screened
cable
Unscreened
cable
CUE
* Both ends of the screened cable between filter and
connection box must be connected to earth
Fig. 33 Submersible pump with connection box and screened
cable
screened motor cable
M
screened motor
cable
Filter M
Unscreened
drop cable
Filter
M
Screened Unscreened
cable drop cable
Filter
M
Connection
box *