Operating Conditions; Frequency Converter Operation - Grundfos MG serie Montage- Und Betriebsanleitung

5.5 Cable entry/screwed connection
Motors are supplied without screwed cable entries. The table
below shows the number and size of the cable entry holes of the
terminal box according to EN 50262.
Frame Number x
Model
size dimensions
2 x (M20 x
71, 80 B, C, H
1.5)
90, 100 B, C, D, H 4 x M20
112, 132 C, D, F, H 4 x M25
4 x M40
160, 180 F, H
2 x M20

6. Operating conditions

6.1 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 section
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.
Max. ambient
temperature at full
Efficiency class
load
[°C]
NA +40
IE2
+60
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
90
80
70
60
50
20 25 30 35 40 45
1000
Fig. 1 Motor output in relation to temperature/installation
altitude
Description
The holes have precast
threads and are closed
with knock-out cable
entries.
The holes are closed
with knock-out cable
entries.
11.2 Motor bearings.
Max. installation
altitude above sea
level at full load
[m]
1000
3500
IE3/IE2,MG
50 55 60 65 70 75 80
t
C
2250 3500 4750 m
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:
• 4750 m above sea level:
As both operating conditions apply, the motor must not be loaded
more than (0.95 x 0.88) = 83.6 %.
If the motor load is not reduced in case the ambient
Caution
temperature or installation altitude is exceeded, the
motor life will be limited, and the warranty is void.

6.2 Frequency converter operation

All three-phase MG motors with phase insulation can be
connected to a frequency converter.
6.2.1 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
Caution
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.
95 %.
88 %.
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