Synchronous Motors; Frequency Converter Operation - Grundfos NB Installation And Operating Instructions Manual

6.4 Synchronous motors

Pumps fitted with synchronous motors must be
connected to a Grundfos CUE frequency converter.
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Example of installation without filter
Symbol Designation
1 CUE
4 Standard motor
One line Unscreened cable
Double line Screened cable
Synchronous motors must not be
connected directly to mains supply.
The CUE must be of T/C CUE203 followed by
additional numbers and characters. See the CUE
Installation and operating instruction to setup
frequency driver together with synchronous motor.
If another frequency driver brand other than CUE is
required or specified, contact Grundfos.
T/C: CUE203 P1M2T5E20H1BXCXXXSXXXXAXBXCXXXXDX
Prod. no: 12345678
S/N: 123456G234
1.5 kW (400V)
IN: 3x380-500 V 50/60Hz 3.7A
OUT: 3x0-Vin 0-100Hz 4.1 A 2.8 kVA
CHASSIS/IP20 Tamb. 45C/122F
IIIIIIIIIIIBAR CODEIIIIIIIIIII
Listed 76X1 E134261 Ind. Contr. Eq.
See manual for prefuse
CAUTION:
SEE MANUAL / VOIR MANUEL
WARNING:
STORED CHARGE DO NOT TOUCH UNTIL
4 MIN AFTER DISCONNECTION
CHARGE RESIDUELLE, ATTENDRE
4 MIN APRES DECONNEXION
Example of CUE nameplate
Text description
CUE (product name)
T/C
203... (internal code)

6.5 Frequency converter operation

All three-phase motors can be connected to a
frequency converter.
Frequency converter operation will often expose the
motor insulation system to a heavier load and cause
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the motor to be more noisy than usual due to eddy
currents caused by voltage peaks.
A large motor driven via a frequency converter will be
loaded by bearing currents.
Check these operating conditions if the pump is
driven via a frequency converter:
Operating
conditions
2-pole motors from
45 kW, 4-pole
motors from
37 kW and 6-pole
motors from 30 kW
Noise critical
applications
Particularly noise
critical applications
Cable length
Supply voltage up
to 500 V
MADE IN DENMARK
Supply voltage
between 500 V and
690 V
Supply voltage of
690 V and higher
Action
Check that one of the motor
bearings is electrically
isolated.
Contact Grundfos.
Fit an output filter between the
motor and the frequency
converter. This reduces the
voltage peaks and thus the
noise.
Fit a sinusoidal filter.
Fit a cable that meets the
specifications laid down by the
frequency converter supplier.
The length of the cable
between motor and frequency
converter affects the motor
load.
Check that the motor is
suitable for frequency
converter operation.
Fit a sinusoidal filter between
the motor and the frequency
converter which reduces the
voltage peaks and thus the
noise, or check that the motor
has reinforced insulation.
Fit a sinusoidal filter and check
that the motor has reinforced
insulation.
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