Single-Phase Connection; Terminal Box Positions; Frequency Converter Operation - Grundfos CRT Serie Montage- Und Betriebsanleitung

7.3 Single-phase connection

Mains supply [V]
"Low voltage"
50 Hz 220-230
Fig. 15 Connection, "low voltage", 0.37 - 0.75 kW
Fig. 16 Connection, "high voltage", 0.37 - 0.75 kW
Fig. 17 Connection, "low voltage", 1.1 - 2.2 kW
Fig. 18 Connection, "high voltage", 1.1 - 2.2 kW
Single-phase Grundfos motors incorporate a thermal switch and
require no additional motor protection.
10
"High voltage"
/ 240

7.4 Terminal box positions

The terminal box can be turned to four positions, in 90 ° steps.
Follow this procedure:
1. If necessary, remove the coupling guards. Do not remove the
coupling.
2. Remove the bolts securing the motor to the pump.
3. Turn the motor to the required position.
4. Fit and tighten the bolts.
5. Fit the coupling guards.
6. Carry out the electrical connection as shown in the diagram
inside the terminal box cover.

7.5 Frequency converter operation

7.5.1 Motors supplied by Grundfos
All three-phase MG motors with phase insulation can be connected
to a frequency converter.
7.5.2 Phase insulation MG 71 and 80
MG motors, frame sizes 71 and 80, do not have phase insulation as
standard. The motors are not suitable for frequency converter
operation as they are not protected against the voltage peaks
caused by the frequency converter operation. Only motors with a
rated voltage equal to or above 460 V have phase insulation.
Grundfos motors, types MG 71 and MG 80, for
supply voltages up to and including 440 V without
phase insulation (see motor nameplate) must be
Caution
protected against voltage peaks above 650 V (peak
value) between the supply terminals.
We recommend you to protect all other motors against voltage
peaks higher than 1200 V by 2000 V/μsec.
The above disturbances, i.e. both increased acoustic noise and
detrimental voltage peaks, can be eliminated by fitting an LC filter
between the frequency converter and the motor.
For further information, please contact the frequency converter or
motor supplier.
Other motor makes than those supplied by Grundfos
Please contact Grundfos or the motor manufacturer.