English (GB)
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7. Electrical connection
The electrical connection should be carried out by an
authorized electrician in accordance with local
regulations.
The electrical connection should be carried out as
shown in the wiring diagram inside the terminal box
cover.
The operating voltage and frequency are marked on
the pump nameplate. Please make sure that the
motor is suitable for the power supply on which it will
be used.
Single-phase Grundfos motors incorporate a
thermal switch and require no additional motor
protection.
Three-phase motors must be connected to a motor-
protective circuit breaker.
The terminal box can be turned to four positions, in
90 ° steps. See fig. 12.
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. Replace and tighten the bolts.
5. Replace the coupling guards.
Fig. 12 Terminal box positions
7.1 Frequency converter operation
7.1.1 Motors supplied by Grundfos
All three-phase motors supplied by Grundfos can be
connected to a frequency converter.
Depending on the frequency converter type, this may
cause increased acoustic noise from the motor.
Furthermore, it may cause the motor to be exposed
to detrimental voltage peaks.
We recommend to protect all other motors against
voltage peaks higher than 850 V.
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.
7.2 Other motor makes
If other motors makes than those supplied by
Grundfos are used, contact Grundfos or the motor
manufacturer.
Warning
Before removing the terminal box cover
and before any removal/dismantling of the
pump, make sure that the power supply
has been switched off.
The pump must be connected to an
external mains switch with a minimum
contact gap of 3 mm in all poles.
TM00 4257 2294
Grundfos motors, types MG 71 and MG 80
as well as MG 90 (1.5 kW, 2-pole), for
supply voltages up to and including 440 V
(see motor nameplate), must be protected
against voltage peaks higher than 650 V
(peak value) between the supply terminals.
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