5.2.2 Acoustic noise and voltage peaks
Frequency converter operation may cause increased acoustic noise
from the motor and will often expose the motor insulation system to
a heavier load due to voltage peaks reducing motor life. To prevent
the voltage peaks from damaging the motor, make sure to observe
the limits of IEC 60034-17.
Increased acoustic noise and detrimental voltage peaks can be
eliminated by fitting an output filter between the frequency converter
and the motor. For further details, contact your frequency converter
supplier or Grundfos.
The figure below shows the maximum permissible voltage peaks
measured at the motor terminals for a specific rise time.
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
t [m S]
800
900
1000
1100
1200
1300
1400
U
[V]
TM044556
Maximum values for voltage peaks
How to eliminate problems with noise
•
Noise-critical applications:
Fit an output filter between the frequency converter and the
motor. This will reduce the voltage peaks and consequently the
noise.
•
Particularly noise-critical applications:
Fit a sinusoidal filter. This will reduce the voltage peaks and
optimise the sinusoidal wave of the power supply to the motor.
5.2.3 Cable length
The length of the cable between motor and frequency converter
affects the motor load. Fit a cable that meets the specifications laid
down by the frequency converter supplier.
5.2.4 Speed
Basically, MG motors are not suitable for oversynchronous
operation. Contact Grundfos if oversynchronous operation is
required.
Oversynchronous operation means that the motor runs at a
frequency higher than 60 Hz. This can be achieved by using a
frequency converter.
6. Mechanical installation
The installation must be carried out by authorised persons in
accordance with local regulations.
Check by hand that the shaft rotates freely.
WARNING
Body injury
Death or serious personal injury
‐
If you test the motor without any device fitted to it,
make sure that the key is secured in the shaft keyway,
so that it cannot be ejected when starting the motor.
WARNING
Crushing of feet
Death or serious personal injury
‐
Wear personal protective equipment and attach lifting
equipment to the motor eyebolts when handling the
product.
‐
Keep other persons at a safe distance when handling
the product.
CAUTION
Crushing of feet
Minor or moderate personal injury
‐
Make sure that the eyebolts are secured in position.
6.1 Clearance
To ensure sufficient air circulation, a clearance of minimum 50 mm
must be available over/around the motor.
6.2 Terminal box positions
TM045510
Permissible terminal box positions
In case of vertically installed motors, the terminal box must not fall
more than 10° below the horizontal plane.
Make sure that the motor drain holes are positioned so that
condensed water can escape from the motor.
See the section about drain holes.
Related information
9
English (GB)
