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

6.6 EMC-correct installation

This section gives guidelines for good practice when installing the
CUE. Follow these guidelines to meet EN 61800-3, first
environment.
• Use only motor and signal cables with a braided metal screen
in applications without output filter.
• There are no special requirements to supply cables, apart
from local requirements.
• Leave the screen as close to the connecting terminals as
possible. See fig. 38.
• Avoid terminating the screen by twisting the ends. See fig. 39.
Use cable clamps or EMC screwed cable entries instead.
• Connect the screen to ground at both ends for both motor and
signal cables. See fig. 40. If the controller has no cable
clamps, connect only the screen to the CUE. See fig. 41.
• Avoid unscreened motor and signal cables in electrical
cabinets with variable frequency drives.
• Make the motor cable as short as possible in applications
without output filter to limit the noise level and minimise
leakage currents.
• Screws for ground connections must always be tightened
whether a cable is connected or not.
• Keep main cables, motor cables and signal cables separated
in the installation, if possible.
Other installation methods may give similar EMC results if the
above guidelines for good practice are followed.
Fig. 38 Example of stripped cable with screen
Fig. 39 Do not twist the screen ends
Controller
Fig. 40 Example of connection of a 3-conductor bus cable with
screen connected at both ends
Controller
Fig. 41 Example of connection of a 3-conductor bus cable with

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
1 x 200-240 V*
3 x 200-240 V
3 x 380-500 V
3 x 525-600 V
3 x 525-690 V
* Single-phase input - three-phase output.
Description of RFI filter types
C1: For use in domestic areas
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 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 variable-
frequency-driven motor.
Two types of output filter are available as accessories for the
CUE:
• dU/dt filters
• sine-wave filters.
CUE
Use of output filters
Pump type
SP, BM, BMB with
380 V motor and up
Other pumps, noise
reduction
Other pumps, higher
noise reduction
Pumps with 690 V
motor
The lengths stated apply to the motor cable.
screen connected at the CUE (controller with no cable
clamps)
Typical shaft power P2
1.5 - 10 hp
1 - 60 hp
0.75 - 125 hp
1 - 10 hp
15 - 125 hp
Typical shaft
power P2 filter [ft]
Up to 10 hp
15 hp and up
Up to 10 hp
15 hp and up
Up to 10 hp
15 hp and up
All
CUE
RFI filter type
C1
C1
C1
C3
C3
dU/dt Sine-wave
filter [ft]
– 0-1000
0-500 500-1000
– 0-1000
0-500 500-1000
– 0-1000
– 0-1000
– 0-1000
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