5. Operating conditions
5.1 Ambient temperature and installation altitude
Grundfos motors are designed for operation at temperatures up to
40 °C. Grundfos MG motors are capable of continuous operation at
ambient temperatures up to 60 °C, however subject to a shorter
bearing life. See the section about motor bearings.
The ambient temperature and the installation altitude are important
factors for the motor life. The table below shows max. ambient
temperature and max. installation altitude.
The table does not show combined maximum values, meaning that
the motor is not capable of operating at +60 °C at an altitude of
3500 m at the same time.
Efficiency class
Max. ambient tem-
perature at full load
[°C]
Max. installation alti-
tude above sea level
at full load
[m]
NA +40 1000
IE2
+60 3500
IE3
If these values are exceeded, the motor must not be fully loaded
due to the risk of overheating.
Overheating may result from excessive ambient temperatures or
low density and consequently low cooling effect of the air.
In such cases, it may be necessary to reduce the load or use a
motor with a higher rated output.
The curves below show the maximum motor load of the various
efficiency classes.
P2
100
20
t
1000
50
60
70
80
90
70656055504540353025 8075
475035002250 m
C
%
IE3/IE2,MG
TM051168
Motor output in relation to temperature/installation altitude
Example
The example shows an IE2 motor under these operating conditions:
• Ambient temperature: 65 °C.
• Installation altitude above sea level: 4750 m.
Maximum load of the motor:
• Ambient temperature of 65 °C: 95 %.
• 4750 m above sea level: 88 %.
As both operating conditions apply, the motor must not be loaded
more than (0.95 × 0.88) = 83.6 %.
If the motor load is not reduced in case the ambient tem-
perature or installation altitude is exceeded, the motor life
will be limited, and the warranty is void.
Related information
10.2 Motor bearings
5.2
Frequency converter operation
All three-phase MG motors with phase insulation can be connected
to a frequency converter.
5.2.1 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 frequency converter operation.
Only motors with a rated voltage equal to or above 460 V have
phase insulation.
Frequency converter operation of MG motors without
phase insulation will cause damage to the motor.
MG 90 to 180
MG motors, frame sizes 90 to 180, have phase insulation. The
motors are suitable for frequency converter operation, subject to
these precautions:
Operating conditions for MG motors to be used for frequency
converter operation
• Supply voltage up to 400 V:
- Check that the motor has phase insulation. (Only motors with
a rated voltage equal to or above 460 V have phase
insulation.)
• Supply voltage above 400 V:
- Check that the motor has phase insulation. (Only motors with
a rated voltage equal to or above 460 V have phase
insulation.)
- Fit a sine-wave filter between the motor and the frequency
converter.
8
English (GB)
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